Every sentencehas a source.

Toktaş D, Atilla R · Sao Paulo Medical Journal · doi:10.1590/1516-3180.2026.3641.27032026

Melasma prevalence was 37.8% among 450 pregnant women in Turkey; family history and darker skin type were important risk factors.

Melasma

Reynolds RV, Yeung H, Cheng CE, ve ark. · Journal of the American Academy of Dermatology · doi:10.1016/j.jaad.2023.12.017

The American Academy of Dermatology's current guideline; it gives strong recommendations for retinoids, benzoyl peroxide, topical antibiotics and isotretinoin for severe acne, and conditional recommendations for azelaic acid and hormonal options.

Acne

NHS · NHS (UK National Health Service)

Summarizes the symptoms and triggers of atopic eczema, how to use moisturizers and when to see a doctor in a patient-friendly way.

Atopic dermatitis

Polaskey MT, Chang CH, Daftary K, Fakhraie S, Miller CH, Chovatiya R · JAMA Dermatology · doi:10.1001/jamadermatol.2024.1987

A meta-analysis covering 121 studies calculated the worldwide prevalence of seborrheic dermatitis at 4.38%, and 5.64% in adults.

Seborrheic dermatitis

American Academy of Dermatology · AAD Public Education

Offers basic care advice such as choosing a shampoo suited to your hair type, focusing shampoo on the scalp, using conditioner after every wash and protecting hair from the sun.

Wavy hair (Type 2A–2C)

NHS · NHS (UK National Health Service)

Summarizes rosacea symptoms, common triggers and treatment options in a patient-friendly way.

Rosacea

Sidbury R, Alikhan A, Bercovitch L, ve ark. · Journal of the American Academy of Dermatology · doi:10.1016/j.jaad.2022.12.029

Provided evidence-based recommendations for moisturizers, topical corticosteroids, calcineurin inhibitors, and JAK and PDE-4 inhibitors in adult atopic dermatitis.

Atopic dermatitis

De Almeida CV, Antiga E, Lulli M · Microorganisms · doi:10.3390/microorganisms11061420

Reviewed the potential of certain probiotics and their metabolites to improve skin barrier function and reduce inflammation.

Keratosis pilarisSkin and hair in PCOSThe eye area: dark circles, puffiness and eczema

Winters RD, Mitchell M · StatPearls [Internet]

A clinical reference summarizing the bacterial, fungal, viral and inflammatory types of folliculitis and approaches to diagnosis and treatment.

Folliculitis and body acne

Teede HJ, Tay CT, Laven J, Dokras A, et al. · Fertil Steril · doi:10.1016/j.fertnstert.2023.07.025

An international guideline with 254 recommendations and practice points; it emphasized a healthy lifestyle, emotional well-being and evidence-based medical treatment.

Skin and hair in PCOS

American Academy of Dermatology · AAD (Amerikan Dermatoloji Akademisi)

Explains the symptoms of seborrheic dermatitis, who gets it and treatment approaches in a patient-friendly way.

Seborrheic dermatitis

Shah N (DermNet) · DermNet

Notes that periorificial dermatitis is slightly more common in fair-skinned women and usually affects young and middle-aged women between 20 and 45.

Perioral dermatitis

Harris-Tryon TA, Grice EA · Science · doi:10.1126/science.abo0693

Summarized that the microbiota living on the skin is a fundamental part of barrier function, protecting against harmful microbes, balancing the immune response and strengthening the epithelium.

Sensitive skinDryness and barrier damage

Paichitrojjana A, Chalermchai T · Clin Cosmet Investig Dermatol · doi:10.2147/CCID.S395654

Yeast-related folliculitis was found in 28.8% of 320 patients diagnosed with acne; itching and placement on the upper back were important clues.

Folliculitis and body acne

Habeebuddin M, Karnati RK, Shiroorkar PN, et al. · Pharmaceutics · doi:10.3390/pharmaceutics14030557

Reviewed how topical probiotics may show positive effects in inflammatory skin conditions such as acne, rosacea and psoriasis.

Folliculitis and body acne

Kamp E, Ashraf M, Musbahi E, DeGiovanni C · Clin Exp Dermatol · doi:10.1111/ced.15327

Reported that the proportion of hairs in the growth phase decreases after menopause, and that female pattern hair loss and frontal fibrosing alopecia are associated with perimenopause and menopause.

Skin and hair in menopause

Kamp E, Ashraf M, Musbahi E, DeGiovanni C · Clin Exp Dermatol · doi:10.1111/ced.15308

Reviewed how estrogen plays a role in water loss from the skin and in dermal collagen, and how menopause is associated with dryness, itching, hidradenitis and psoriasis.

Skin and hair in menopause

Ratanapokasatit Y, Laisuan W, Rattananukrom T, Petchlorlian A, et al. · Life (Basel) · doi:10.3390/life12070936

Stated that the gut and skin microbiota influence skin aging through oxidative stress, inflammation and immunity, and that anti-aging probiotic studies are still limited.

Premature aging

Park J, Schwardt NH, Jo JH, Zhang Z, et al. · Journal of Investigative Dermatology · doi:10.1016/j.jid.2021.04.034

Showed that children's skin microbiome shifts toward an adult type during puberty; in girls, oil-loving bacteria and yeasts increased, and this was linked to sex hormones.

Teens

Zouboulis CC, Blume-Peytavi U, Kosmadaki M, Roó E, et al. · Climacteric · doi:10.1080/13697137.2022.2050206

Reviewed how menopause can lead to dryness, itching, thinning and sagging of the skin, and reduced density and texture changes in hair, and how these symptoms affect quality of life.

40s50s

Larson PJ, Zhou W, Santiago A, Driscoll S, et al. · Nature Aging · doi:10.1038/s43587-022-00287-9

Showed that in older age, microbiome changes are linked more to frailty than to calendar age, and that skin microbiome balance is especially important during this period.

60 and beyond

Mahmud MR, Akter S, Tamanna SK, Mazumder L, Esti IZ, Banerjee S ve ark. · Gut Microbes · doi:10.1080/19490976.2022.2096995

Examined the possible effects of the gut microbiome on skin health and approaches that target this axis.

The gut-skin connection: how does what you eat affect your skin?

Daou H, Paradiso M, Hennessy K, Seminario-Vidal L · Dermatology and Therapy · doi:10.1007/s13555-020-00460-1

Systematically reviewed the role of the skin and gut microbiome in rosacea and its associations with small intestinal bacterial overgrowth, irritable bowel syndrome and inflammatory bowel diseases.

Rosacea

Laughter MR, Maymone MBC, Mashayekhi S, ve ark. · British Journal of Dermatology · doi:10.1111/bjd.19580

Reported that atopic dermatitis ranks 15th among non-fatal diseases, carries the highest burden of all skin diseases and shows two separate peaks in frequency, in early childhood and in middle age.

Atopic dermatitis

Tao R, Li R, Wang R · Experimental Dermatology · doi:10.1111/exd.14450

Showed that the ratio between yeast species changes in seborrheic dermatitis and dandruff, that increased staph is linked to water loss and higher pH, and that the yeast is linked to itching and severity.

Seborrheic dermatitis

Searle T, Ali FR, Al-Niaimi F · Journal of Cosmetic Dermatology · doi:10.1111/jocd.14060

A systematic review found that misuse of topical corticosteroids is the best-proven cause of perioral dermatitis, and noted that options such as tetracyclines, metronidazole and azelaic acid need further research.

Perioral dermatitis

Uberoi A, Bartow-McKenney C, Zheng Q, ve ark. · Cell Host & Microbe · doi:10.1016/j.chom.2021.05.011

Showed in an experimental model that beneficial skin microbiota is necessary for the barrier to form and repair properly, and that this effect works through a receptor in skin cells.

Dryness and barrier damage

Constantinou A, Kanti V, Polak-Witka K, Blume-Peytavi U, Spyrou GM, Vogt A · Biomedicines · doi:10.3390/biomedicines9030236

Showed that research on the link between the scalp microbiome and hair physiology is promising but still at an early stage.

Female pattern hair loss

Griffiths CEM, Armstrong AW, Gudjonsson JE, Barker JNWN · The Lancet · doi:10.1016/S0140-6736(20)32549-6

Reviewed psoriasis as a chronic inflammatory disease in which genetic, immune and environmental factors act together, accompanied by other conditions.

Psoriasis

Montero-Vilchez T, Segura-Fernández-Nogueras MV, Pérez-Rodríguez I, et al. · Journal of Clinical Medicine · doi:10.3390/jcm10020359

Showed that water loss is increased and moisture levels markedly lower in psoriasis plaques than in healthy skin, and that these measurements are linked to disease severity.

Psoriasis

Lephart ED, Naftolin F · Dermatol Ther (Heidelb) · doi:10.1007/s13555-020-00468-7

Reviewed how estrogen deficiency impairs collagen, elastin and barrier function, and noted that cosmetic ingredients with selective estrogen receptor modulator activity are promising.

Skin and hair in menopause

Boyajian JL, Ghebretatios M, Schaly S, Islam P, Prakash S · Nutrients · doi:10.3390/nu13124550

Reviewed how the gut microbiota may influence cellular aging via the gut-skin axis, and how probiotics and prebiotics are promising options in this process.

Skin and hair in menopausePremature aging

Punyani S, Tosti A, Hordinsky M, et al. · Skin Appendage Disorders 7(3):183-193 · doi:10.1159/000512786

Questioned the belief that frequent washing damages hair, and reported that adjusting wash frequency to the person's scalp condition can improve scalp comfort.

Straight hair (Type 1)Fine and thinning hairOily scalp

Malinauskyte E, Shrestha R, Cornwell PA, et al. · International Journal of Cosmetic Science 43(1):26-37 · doi:10.1111/ics.12663

Showed that low-molecular-weight hydrolyzed keratin can penetrate curly hair strands and improve some of the strand's physical properties.

Curly and coily hair (Type 3–4)Colored, bleached and chemically treated hair (including keratin and perms)

Salminen S, Collado MC, Endo A, Hill C, Lebeer S, Quigley EMM ve ark. · Nature Reviews Gastroenterology & Hepatology · doi:10.1038/s41575-021-00440-6

Defined a postbiotic as a preparation of inanimate microorganisms and/or their components that confers a health benefit.

Probiotics, prebiotics, postbiotics: what's the difference, and what do they do for skin?

De Pessemier B, Grine L, Debaere M, Maes A, Paetzold B, Callewaert C · Microorganisms · doi:10.3390/microorganisms9020353

Reviewed findings on the link between gut microbial imbalance and acne, atopic dermatitis, psoriasis and rosacea.

The gut-skin connection: how does what you eat affect your skin?

Goodarzi A, Mozafarpoor S, Bodaghabadi M, Mohamadi M · Dermatologic Therapy · doi:10.1111/dth.13279

Reviewed evidence that probiotics suppress the acne-associated bacterium and reduce inflammatory signals in the lab, and that oral probiotics may complement standard treatment in mild to moderate acne.

Acne

Knackstedt R, Knackstedt T, Gatherwright J · Experimental Dermatology · doi:10.1111/exd.14032

Systematically reviewed studies on the role of topically applied probiotics in conditions such as atopic dermatitis, acne and rosacea, and identified areas needing further research.

AcneRosaceaPerioral dermatitisMelasmaPost-inflammatory dark spots and sun spotsContact dermatitisOily skin20s30sProbiotics, prebiotics, postbiotics: what's the difference, and what do they do for skin?

Yu Y, Dunaway S, Champer J, Kim J, Alikhan A · British Journal of Dermatology · doi:10.1111/bjd.18088

Reported that oral and topical probiotics generally showed positive results in some inflammatory skin diseases, but that the results need to be confirmed by more studies.

AcneSeborrheic dermatitisProbiotics, prebiotics, postbiotics: what's the difference, and what do they do for skin?

Thiboutot D, Anderson R, Cook-Bolden F, ve ark. · Journal of the American Academy of Dermatology · doi:10.1016/j.jaad.2020.01.077

Summarized symptom-based treatment options for redness, bumps, blood vessels and eye symptoms, and the importance of daily skincare.

Rosacea

Medgyesi B, Dajnoki Z, Béke G, ve ark. · Journal of Investigative Dermatology · doi:10.1016/j.jid.2020.02.025

Found marked disruption of barrier proteins, lipid layers and cell junctions in inflammatory rosacea; the picture resembled atopic dermatitis, and the importance of barrier-repairing treatments was emphasized.

Rosacea

Langan SM, Irvine AD, Weidinger S · The Lancet · doi:10.1016/S0140-6736(20)31286-1

Summarized that atopic dermatitis is a combination of genetic predisposition, epidermal dysfunction and T cell–driven inflammation, and that it leads the global burden caused by skin diseases.

Atopic dermatitis

Chen W, Dai R, Li L · Journal of the European Academy of Dermatology and Venereology · doi:10.1111/jdv.16166

A meta-analysis covering 51,783 people from 18 countries found that sensitive skin affects 45% of women and 33% of men, and that being female is a risk factor.

Sensitive skin

Do LHD, Azizi N, Maibach H · American Journal of Clinical Dermatology · doi:10.1007/s40257-019-00499-7

Updated the differential diagnosis and approaches, emphasizing that there's no specific treatment protocol for sensitive skin and that personalized skincare is recommended.

Sensitive skin

Keum HL, Kim H, Kim HJ, ve ark. · Microorganisms · doi:10.3390/microorganisms8071032

Showed in 42 women that the bacterial and fungal communities of sensitive and non-sensitive cheek skin differ, and that this structure varies with the perceived level of sensitivity.

Sensitive skin

Polak-Witka K, Rudnicka L, Blume-Peytavi U, Vogt A · Experimental Dermatology · doi:10.1111/exd.13935

Reviewed how the microbiome of the scalp and hair follicles interacts with the immune system and its possible role in inflammatory scalp diseases.

Dandruff and itchy scalpFemale pattern hair lossHair loss from stress, dieting and after pregnancyFine and thinning hairSensitive and itchy scalp

Asghar F, Shamim N, Farooque U, Sheikh H, Aqeel R · Cureus · doi:10.7759/cureus.8320

Reviewed how medications, trauma and physical or emotional stress can trigger telogen effluvium, and that finding and removing the cause is key to treatment.

Hair loss from stress, dieting and after pregnancy

Parisi R, Iskandar IYK, Kontopantelis E, Augustin M, Griffiths CEM, Ashcroft DM · BMJ · doi:10.1136/bmj.m1590

Showed that adult psoriasis prevalence ranges from 0.14% in East Asia to 1.99% in Australasia, and is 1.92% in Western Europe.

Psoriasis

Armstrong AW, Read C · JAMA · doi:10.1001/jama.2020.4006

Summarized how psoriasis develops through the IL-23/IL-17 axis and the topical, light, systemic and biologic treatment options.

Psoriasis

Nassau S, Fonacier L · Medical Clinics of North America · doi:10.1016/j.mcna.2019.08.012

Summarized the role of patch testing in diagnosing allergic contact dermatitis, the common allergens and the importance of allergen avoidance in treatment.

Contact dermatitis

Brites GS, Ferreira I, Sebastião AI, et al. · Pharmacological Research · doi:10.1016/j.phrs.2020.105282

Stressed that allergic contact dermatitis is a T cell-mediated inflammation, that allergen avoidance is the foundation of treatment, and the importance of barrier creams and moisturizers.

Contact dermatitis

Shamasbi SG, Ghanbari-Homayi S, Mirghafourvand M · Eur J Nutr · doi:10.1007/s00394-019-02033-1

Across 13 studies of 855 women with PCOS, probiotics and synbiotics increased SHBG and lowered FAI; no difference was found in testosterone or hirsutism scores.

Skin and hair in PCOS

Bashir A, Lambert P · Journal of Applied Microbiology · doi:10.1111/jam.14479

Bacteria were found in the vast majority of used makeup products; makeup sponges were the most contaminated group.

How do you clean makeup brushes? Brush hygiene and removing makeup the right way

Farage MA · Frontiers in Medicine · doi:10.3389/fmed.2019.00098

By reviewing surveys worldwide, showed that about 60–70% of women and 50–60% of men report some degree of sensitive skin.

Sensitive skin

Mekić S, Jacobs LC, Gunn DA, ve ark. · Journal of the American Academy of Dermatology · doi:10.1016/j.jaad.2018.12.038

Dry skin was found in 60% of 5,547 middle-aged and older participants; age, female sex, outdoor temperature and eczema were determining factors, and daily cream use was associated with less dryness.

Dryness and barrier damage

Abanmi A, Al-Enezi M, Al Hammadi A, Galadari I, Kibbi AG, Zimmo S · Journal of Dermatological Treatment · doi:10.1080/09546634.2018.1542807

Post-inflammatory dark spots were found in 87.2% of 262 acne patients; 69% of patients picked at their pimples and half found the spots more bothersome than the acne.

Post-inflammatory dark spots and sun spots

Almohanna HM, Ahmed AA, Tsatalis JP, Tosti A · Dermatology and Therapy · doi:10.1007/s13555-018-0278-6

Noted that vitamin and mineral deficiencies may be a modifiable risk factor in hair loss, but that large studies are needed to clarify the effect of supplements.

Female pattern hair lossHair loss from stress, dieting and after pregnancy

Fyhrquist N, Muirhead G, Prast-Nielsen S, et al. · Nature Communications · doi:10.1038/s41467-019-12253-y

Showed that psoriasis and eczema can be distinguished by different microbial patterns, with several communities of microorganisms playing a role together in psoriasis.

Psoriasis

Navarro-López V, Martínez-Andrés A, Ramírez-Boscá A, et al. · Acta Dermato-Venereologica · doi:10.2340/00015555-3305

In a 12-week study, 66.7% of the probiotic group reached a 75% reduction in disease severity versus 41.9% of the placebo group; flare-up risk was lower during follow-up.

Psoriasis

Alinaghi F, Bennike NH, Egeberg A, Thyssen JP, Johansen JD · Contact Dermatitis · doi:10.1111/cod.13119

Found contact allergy prevalence of 20.1% in the general population, 27.9% in women and 13.2% in men; the most common allergen was nickel, followed by fragrance mix.

Contact dermatitis

Ahlström MG, Thyssen JP, Wennervaldt M, Menné T, Johansen JD · Contact Dermatitis · doi:10.1111/cod.13327

Showed that nickel is the most common cause of contact allergy worldwide, with a prevalence of 8–19% among adults in Europe and markedly higher rates in women.

Contact dermatitis

Ogunbiyi A · Clin Cosmet Investig Dermatol · doi:10.2147/CCID.S149250

Reported that shaving or plucking triggers an inflammatory reaction when sharp, growing hair tips pierce the skin, and that stopping shaving usually resolves the condition.

Folliculitis and body acne

Carmina E, Azziz R, Bergfeld W, Escobar-Morreale HF, et al. · J Clin Endocrinol Metab · doi:10.1210/jc.2018-02548

Recommended evaluating every woman with female pattern hair loss for androgen excess and starting treatment with topical minoxidil.

Skin and hair in PCOSSkin and hair in menopause

Lee YB, Byun EJ, Kim HS · Journal of Clinical Medicine · doi:10.3390/jcm8070987

Reviewed evidence that in acne, the decisive factor is not a single bacterium but a loss of diversity and balance in the skin microbiome.

Oily skin

Gavazzoni Dias MFR · Skin Appendage Disorders 5(3):131-134 · doi:10.1159/000493588

Discusses how non-lathering cleansing conditioners (co-wash) give softness to curly and dry hair but may fall short for an oily scalp and a tendency toward dandruff.

Wavy hair (Type 2A–2C)Curly and coily hair (Type 3–4)

Grimshaw SG, Smith AM, Arnold DS, et al. · PLOS ONE 14(12):e0225796 · doi:10.1371/journal.pone.0225796

Compared the diversity and amount of yeast and bacterial communities on healthy and dandruff-affected scalps and showed that the balance shifts on the dandruff side.

Oily scalpScalp care: what causes dandruff and itching, and where does healthy hair begin?

Kim HJ, Kim JJ, Myeong NR, Kim T, et al. · Scientific Reports · doi:10.1038/s41598-019-53266-3

Showed that the skin microbiome of women aged 56–63 differed in structure from that of women aged 25–35, and that the communication network between microbes was weaker.

50s

Lyons AB, Moy L, Moy R, Tung R · The Journal of Clinical and Aesthetic Dermatology

Reviewed how skin processes such as cell division, DNA repair and barrier function show regular changes over the course of the day.

Sleep and skin health: how does lack of sleep affect your skin?

Zasada M, Budzisz E · Advances in Dermatology and Allergology · doi:10.5114/ada.2019.87443

Explained the effects of retinoids on skin cell renewal and collagen structure.

Can you use retinol and vitamin C together? A guide to layering acids, retinol and vitamin C

Dréno B, Pécastaings S, Corvec S, ve ark. · Journal of the European Academy of Dermatology and Venereology · doi:10.1111/jdv.15043

Showed that people with acne do not have more of this bacterium in their pores; rather, loss of microbial diversity and activation of innate immunity set off inflammation.

Acne

Gether L, Overgaard LK, Egeberg A, Thyssen JP · British Journal of Dermatology · doi:10.1111/bjd.16481

A meta-analysis covering 41 populations found that rosacea affects 5.46% of the adult population, occurring in 5.41% of women and 3.90% of men, and is most common between ages 45 and 60.

Rosacea

Gallo RL, Granstein RD, Kang S, ve ark. · Journal of the American Academy of Dermatology · doi:10.1016/j.jaad.2017.08.037

Recommended classifying rosacea by the symptoms a person has (phenotype) instead of subtypes and summarized the shared underlying disease processes.

Rosacea

Makrgeorgou A, Leonardi-Bee J, Bath-Hextall FJ, ve ark. · Cochrane Database of Systematic Reviews · doi:10.1002/14651858.CD006135.pub3

After evaluating 39 studies, concluded that currently available oral probiotics probably make little or no difference to eczema symptoms reported by patients.

Atopic dermatitis

Saxena R, Mittal P, Clavaud C, ve ark. · Frontiers in Cellular and Infection Microbiology · doi:10.3389/fcimb.2018.00346

Compared the healthy and dandruff scalp microbiome in 140 women and observed that beneficial bacteria carry pathways linked to producing B vitamins important for hair.

Seborrheic dermatitisDandruff and itchy scalpOily scalpDry scalpScalp care: what causes dandruff and itching, and where does healthy hair begin?

Byrd AL, Belkaid Y, Segre JA · Nature Reviews Microbiology · doi:10.1038/nrmicro.2017.157

Comprehensively summarized the structure of the skin microbiome in health and disease, the relationships between microorganisms and their interaction with the immune system.

Perioral dermatitisMelasmaPost-inflammatory dark spots and sun spotsDandruff and itchy scalpPsoriasisContact dermatitisKeratosis pilarisFolliculitis and body acneSkin and hair in PCOSThe eye area: dark circles, puffiness and eczemaNormal skinCombination skinTeensWhat is the skin microbiome, and how do you keep it balanced?How do you clean makeup brushes? Brush hygiene and removing makeup the right way

Passeron T, Picardo M · Pigment Cell & Melanoma Research · doi:10.1111/pcmr.12684

Proposed that melasma can be viewed as a photoaging disorder that appears in genetically predisposed people.

Melasma

Kaufman BP, Aman T, Alexis AF · American Journal of Clinical Dermatology · doi:10.1007/s40257-017-0333-6

Reviewed how post-inflammatory spots develop after acne, eczema and dermatological procedures, and that they are more common in darker skin.

Post-inflammatory dark spots and sun spots

Fabbrocini G, Cantelli M, Masarà A, Annunziata MC, Marasca C, Cacciapuoti S · International Journal of Women's Dermatology · doi:10.1016/j.ijwd.2018.05.001

Stressed that female pattern hair loss is the most common cause of hair loss in women, and that early diagnosis matters because treatments are more effective at stopping progression than at growing new hair.

Female pattern hair loss

Chang HW, Yan D, Singh R, et al. · Microbiome · doi:10.1186/s40168-018-0533-1

Showed that the microbiome on skin with psoriasis is less stable, with fewer beneficial bacteria and more of one type of staphylococcus, which may be linked to inflammatory pathways.

Psoriasis

Wang JF, Orlow SJ · Am J Clin Dermatol · doi:10.1007/s40257-018-0368-3

A review describing keratosis pilaris as a primary disorder of the pilosebaceous unit; it evaluated topical, systemic and laser treatments.

Keratosis pilaris

Franceschi C, Garagnani P, Parini P, Giuliani C, Santoro A · Nat Rev Endocrinol · doi:10.1038/s41574-018-0059-4

Defined the chronic, low-grade inflammation that develops with age (inflammaging) and emphasized the central role of the gut microbiota in this process.

Premature aging

Draelos ZD · Journal of Cosmetic Dermatology · doi:10.1111/jocd.12490

Explained the science of how moisturizers support the barrier through humectant, emollient and occlusive ingredients.

Dry skin

Seite S, Misery L · Experimental Dermatology · doi:10.1111/exd.13686

Discussed a possible link between sensitive skin and imbalance in the skin microbiota, noting that this area needs more research.

Sensitive skin

Salem I, Ramser A, Isham N, Ghannoum MA · Frontiers in Microbiology · doi:10.3389/fmicb.2018.01459

Reviewed how the gut microbiome can influence skin renewal and immune responses through immune and inflammatory signals (the gut-skin axis).

Teens40sHow does stress show up on your skin? Stress acne, itching and cortisolThe gut-skin connection: how does what you eat affect your skin?

Akdeniz M, Tomova-Simitchieva T, Dobos G, Blume-Peytavi U, Kottner J · Skin Research and Technology · doi:10.1111/srt.12454

Reported that the evidence on the effect of fluid intake on skin hydration is limited and inconsistent.

7 skincare myths: the truth about drinking water, pores and oily skin

Nakatsuji T, Chen TH, Narala S, ve ark. · Science Translational Medicine · doi:10.1126/scitranslmed.aah4680

Showed that beneficial bacteria on healthy skin produce substances that selectively suppress staph, that these bacteria are scarce in atopic dermatitis and that reapplying them reduced the staph load.

Atopic dermatitis

Grice EA, Dawson TL · Current Opinion in Microbiology · doi:10.1016/j.mib.2017.10.024

Summarized that the yeast naturally found on the skin lives on both healthy and diseased skin and interacts with the host through immune and chemical mediators.

Seborrheic dermatitis

Misery L, Ständer S, Szepietowski JC, ve ark. · Acta Dermato-Venereologica · doi:10.2340/00015555-2397

Defined sensitive skin as a syndrome marked by stinging, burning, pain, itching and tingling in response to stimuli that normally shouldn't cause discomfort, which can't be explained by a skin disease.

Sensitive skinSensitive skin

Ogbechie-Godec OA, Elbuluk N · Dermatology and Therapy · doi:10.1007/s13555-017-0194-1

Summarized that melasma is linked to light, hormones and family history, and that combination treatments give better results than single methods.

Melasma

Taraz M, Niknam S, Ehsani AH · Dermatologic Therapy · doi:10.1111/dth.12465

Highlighted that tranexamic acid is used for melasma by different routes, but that its effectiveness needs to be clarified by more studies.

Melasma

Motosko CC, Bieber AK, Pomeranz MK, Stein JA, Martires KJ · Int J Womens Dermatol · doi:10.1016/j.ijwd.2017.09.003

Reviewed physiological skin changes in pregnancy such as pigmentation, melasma, stretch marks and telogen hair shedding.

Skin during pregnancy and after birth

Farahnik B, Park K, Kroumpouzos G, Murase J · Int J Womens Dermatol · doi:10.1016/j.ijwd.2016.11.001

Young age, family history, weight and the baby's birth weight were found to be the most important risk factors; fractional lasers were reported to provide 50-75% improvement in stretch marks.

Skin during pregnancy and after birthPregnancy and postpartum

Shibagaki N, Suda W, Clavaud C, Bastien P, et al. · Sci Rep · doi:10.1038/s41598-017-10834-9

Comparing women aged 21-37 and 60-76, showed that the diversity and makeup of the skin microbiome change markedly with age.

Skin and hair in menopausePremature agingMature skin40s60 and beyond

Krutmann J, Bouloc A, Sore G, Bernard BA, Passeron T · J Dermatol Sci · doi:10.1016/j.jdermsci.2016.09.015

Defined the full set of outside factors affecting skin aging, such as sun, pollution, smoking, diet, stress and sleep, as the 'skin aging exposome'.

Premature agingMature skinHow do you choose a sunscreen, and how much should you apply? What SPF do you need?

Endly DC, Miller RA · Journal of Clinical and Aesthetic Dermatology

Reviewed the evidence for topical retinoids, niacinamide and other options aimed at balancing sebum in oily skin.

Oily skin

Pullar JM, Carr AC, Vissers MCM · Nutrients · doi:10.3390/nu9080866

Reviewed the role of vitamin C in collagen production and antioxidant defense, and noted that its levels in the skin decrease with age and sun exposure.

Mature skinCan you use retinol and vitamin C together? A guide to layering acids, retinol and vitamin C

Gibson GR, Hutkins R, Sanders ME, Prescott SL, Reimer RA, Salminen SJ ve ark. · Nature Reviews Gastroenterology & Hepatology · doi:10.1038/nrgastro.2017.75

Defined a prebiotic as a substance selectively used by host microorganisms that confers a health benefit, and noted that the scope may include the skin.

Probiotics, prebiotics, postbiotics: what's the difference, and what do they do for skin?

Purnamawati S, Indrastuti N, Danarti R, Saefudin T · Clinical Medicine & Research · doi:10.3121/cmr.2017.1363

Summarized the role of humectant, emollient and occlusive ingredients in supporting the barrier in dermatitis.

Dry skin in winter: central heating, cold air and winter skincare

Zaenglein AL, Pathy AL, Schlosser BJ, ve ark. · Journal of the American Academy of Dermatology · doi:10.1016/j.jaad.2015.12.037

The previous comprehensive guideline, emphasizing that antibiotics should not be used alone and should be combined with benzoyl peroxide to limit resistance.

Acne

Misery L, Loser K, Ständer S · Journal of the European Academy of Dermatology and Venereology · doi:10.1111/jdv.13532

Summarized that nerve endings and temperature-sensitive channels, barrier disruption and immune mechanisms may play a role in sensitive skin.

Sensitive skinSensitive skin

Kwon SH, Hwang YJ, Lee SK, Park KC · International Journal of Molecular Sciences · doi:10.3390/ijms17060824

Showed that melasma is a multifaceted picture involving different mechanisms such as sun damage, increased blood vessels and basement membrane disruption.

Melasma

van Zuuren EJ, Fedorowicz Z, Schoones J · Cochrane Database of Systematic Reviews · doi:10.1002/14651858.CD007628.pub4

Showed that minoxidil applied to the scalp significantly increased hair count compared with placebo in female pattern hair loss.

Female pattern hair loss

Mirallas O, Grimalt R · Skin Appendage Disorders · doi:10.1159/000445385

Showed that there is no statistically significant data in the literature supporting a difference in hair loss between pregnancy and the postpartum period.

Hair loss from stress, dieting and after pregnancyPregnancy and postpartum

Bozdag G, Mumusoglu S, Zengin D, Karabulut E, Yildiz BO · Hum Reprod · doi:10.1093/humrep/dew218

PCOS prevalence was found to be 6% by NIH criteria and 10% by Rotterdam and AE-PCOS criteria; hirsutism prevalence was 13%.

Skin and hair in PCOSTeens20s

Chien AL, Qi J, Rainer B, Sachs DL, Helfrich YR · J Am Board Fam Med · doi:10.3122/jabfm.2016.02.150165

Recommended topical azelaic acid or benzoyl peroxide as the main acne treatment in pregnancy; emphasized that oral retinoids are teratogenic and strictly contraindicated.

Skin during pregnancy and after birth

Vrcek I, Ozgur O, Nakra T · J Cutan Aesthet Surg · doi:10.4103/0974-2077.184046

Reviewed how under-eye dark circles arise from a combination of deep facial anatomy, soft tissue changes and skin-related factors, and why treatment should be personalized accordingly.

The eye area: dark circles, puffiness and eczema

Sarkar R, Ranjan R, Garg S, Garg VK, et al. · J Clin Aesthet Dermatol

Reported that darkening around the eyes can result from genetics, excess pigmentation, marks left after atopic and allergic dermatitis, swelling, visible blood vessels and age-related shadowing.

The eye area: dark circles, puffiness and eczema

Engebretsen KA, Johansen JD, Kezic S, Linneberg A, Thyssen JP · Journal of the European Academy of Dermatology and Venereology · doi:10.1111/jdv.13301

Reviewed evidence that low humidity and cold weather weaken the skin barrier, and that dryness and eczema flare-ups increase in the winter months.

Dry skinCombination skinDry skin in winter: central heating, cold air and winter skincare

Xu Z, Wang Z, Yuan C, et al. · Scientific Reports 6:24877 · doi:10.1038/srep24877

Showed that dandruff arises not from microorganisms alone but together with sebum, moisture and the scalp's own characteristics.

Thick and dense hair

Cruz CF, Costa C, Gomes AC, Matamá T, Cavaco-Paulo A · Cosmetics 3(3):26 · doi:10.3390/cosmetics3030026

A review of how shampooing, perming and straightening change the cuticle and cortex structure of the hair shaft.

Colored, bleached and chemically treated hair (including keratin and perms)

Dréno B, Araviiskaia E, Berardesca E, Gontijo G, Sanchez Viera M, Xiang LF ve ark. · Journal of the European Academy of Dermatology and Venereology · doi:10.1111/jdv.13965

Emphasized the importance of gentle cleansing and barrier-focused care in maintaining a healthy skin microbiome.

What is the skin microbiome, and how do you keep it balanced?Is washing your face too much bad? How many times a day should you wash it?How do you clean makeup brushes? Brush hygiene and removing makeup the right way

O'Neill CA, Monteleone G, McLaughlin JT, Paus R · BioEssays · doi:10.1002/bies.201600008

Explained that the gut microbiome can influence the skin's inflammatory responses through the immune system.

The gut-skin connection: how does what you eat affect your skin?

Tan JKL, Bhate K · British Journal of Dermatology · doi:10.1111/bjd.13462

Reported that acne affects about 9.4% of the world's population and is the eighth most common disease worldwide.

Acne

Borda LJ, Wikramanayake TC · Journal of Clinical and Investigative Dermatology · doi:10.13188/2373-1044.1000019

Summarized that dandruff and seborrheic dermatitis are parts of the same disease spectrum, with sebum, fungal colonization and individual sensitivity all playing a role.

Seborrheic dermatitisDandruff and itchy scalpOily scalp

Richters R, Falcone D, Uzunbajakava N, ve ark. · Skin Pharmacology and Physiology · doi:10.1159/000363149

A systematic review of objective measurements showed that the findings most often associated with sensitive skin are impaired barrier function and increased vascular reactivity.

Sensitive skin

Lee AY · Pigment Cell & Melanoma Research · doi:10.1111/pcmr.12404

Reviewed how, beyond pigment cells, skin cells, blood vessels and cells of the deeper layers also contribute to the persistence of melasma.

Melasma

Wang L, Clavaud C, Bar-Hen A, et al. · Experimental Dermatology · doi:10.1111/exd.12684

Confirmed the presence of microbial imbalance on scalps with dandruff in a different population as well.

Dandruff and itchy scalp

Ramos PM, Miot HA · Anais Brasileiros de Dermatologia · doi:10.1590/abd1806-4841.20153370

Summarized how diffuse, non-scarring hair thinning develops through the gradual shrinking of hair follicles, with genetic, hormonal and environmental factors acting together.

Female pattern hair loss

Malkud S · Journal of Clinical and Diagnostic Research · doi:10.7860/JCDR/2015/15219.6492

Stated that telogen effluvium is the most common cause of diffuse hair loss and that shedding begins 3–4 months after the triggering event.

Hair loss from stress, dieting and after pregnancy

Hald M, Arendrup MC, Svejgaard EL, Lindskov R, et al. · Acta Derm Venereol · doi:10.2340/00015555-1825

Suggested that for yeast-related folliculitis, systemic antifungal treatment is probably more effective than topical treatment, and that a combination may be advantageous.

Folliculitis and body acne

Tyler KH · Clin Obstet Gynecol · doi:10.1097/GRF.0000000000000077

Emphasized that most physiological skin changes in pregnancy regress on their own after birth and that reassurance and monitoring are sufficient in most cases.

Skin during pregnancy and after birthPregnancy and postpartum

Gavazzoni Dias MF · International Journal of Trichology 7(1):2-15 · doi:10.4103/0974-7753.153450

A comprehensive review that summarizes, from a dermatological perspective, the ingredients of hair cosmetics such as shampoo, conditioner, dyes and straighteners and their effects on the hair shaft.

Straight hair (Type 1)Wavy hair (Type 2A–2C)Thick and dense hairColored, bleached and chemically treated hair (including keratin and perms)Scalp care: what causes dandruff and itching, and where does healthy hair begin?

Oyetakin-White P, Suggs A, Koo B, Matsui MS, et al. · Clinical and Experimental Dermatology · doi:10.1111/ced.12455

Showed that in women who slept well, the barrier recovered 30% better 72 hours after damage, and signs of intrinsic aging were lower.

20s30sSleep and skin health: how does lack of sleep affect your skin?

Raghunath RS, Venables ZC, Millington GWM · Clinical and Experimental Dermatology · doi:10.1111/ced.12588

Reviewed how hormonal changes during the menstrual cycle can affect oil production, immune response and barrier function, and how some skin conditions can flare with the cycle.

Your menstrual cycle and your skin: why you break out before your period, and what to do

Palma L, Marques LT, Bujan J, Rodrigues LM · Clinical, Cosmetic and Investigational Dermatology · doi:10.2147/CCID.S86822

Observed a slight increase in skin hydration when water intake was increased, especially in people with low daily water intake.

7 skincare myths: the truth about drinking water, pores and oily skin

Simpson EL, Chalmers JR, Hanifin JM, ve ark. · Journal of Allergy and Clinical Immunology · doi:10.1016/j.jaci.2014.08.005

Reported that in 124 high-risk newborns, daily moisturizer application from birth was associated with a 50% relative reduction in atopic dermatitis at 6 months.

Atopic dermatitis

Kim SO, Ah YM, Yu YM, ve ark. · Annals of Allergy, Asthma & Immunology · doi:10.1016/j.anai.2014.05.021

Across 25 randomized trials, found that probiotics were associated with lower disease severity scores in children and adults, but showed no benefit in infants.

Atopic dermatitis

Al-Ghazzewi FH, Tester RF · Beneficial Microbes · doi:10.3920/BM2013.0040

Reviewed evidence that prebiotics and probiotics may have the capacity to improve, maintain and rebalance the skin microbiota, and that topical applications may support the skin's natural defenses.

Sensitive skinDryness and barrier damageKeratosis pilarisSkin during pregnancy and after birthNormal skinSensitive skinProbiotics, prebiotics, postbiotics: what's the difference, and what do they do for skin?

Tan CH, Rasool S, Johnston GA · Clinics in Dermatology · doi:10.1016/j.clindermatol.2013.05.033

Reviewed the mechanisms and common causes of irritant and allergic contact dermatitis on the face, and how it can be treated successfully by avoiding the culprit substance.

Contact dermatitis

Laureano AC, Schwartz RA, Cohen PJ · Clin Dermatol · doi:10.1016/j.clindermatol.2014.02.009

Emphasized that staphylococcus is the most common bacterial cause of folliculitis and that folliculitis must be distinguished from pseudofolliculitis.

Folliculitis and body acne

Rubenstein RM, Malerich SA · J Clin Aesthet Dermatol

Reported that yeast-related folliculitis is often confused with acne, is linked to flora-altering factors such as antibiotic use, and appears on the chest, back and face.

Folliculitis and body acne

Housman E, Reynolds RV · J Am Acad Dermatol · doi:10.1016/j.jaad.2014.05.007

Emphasized that the skin findings of PCOS (acanthosis nigricans, hirsutism, acne, hair loss) give dermatologists a key role in diagnosis.

Skin and hair in PCOS

Buzney E, Sheu J, Buzney C, Reynolds RV · J Am Acad Dermatol · doi:10.1016/j.jaad.2014.05.009

Reviewed how acne, hirsutism and hair loss in PCOS are addressed with a combination of hormonal, metabolic and dermatological treatments.

Skin and hair in PCOS

Gavazzoni Dias MF, de Almeida AM, Cecato PM, et al. · International Journal of Trichology 6(3):95-99 · doi:10.4103/0974-7753.139078

Showed that shampoos with a pH above 5.5 can increase the negative electrical charge and friction on the hair shaft, setting the stage for cuticle damage and breakage.

Straight hair (Type 1)Wavy hair (Type 2A–2C)

Murase JE, Heller MM, Butler DC · Journal of the American Academy of Dermatology · doi:10.1016/j.jaad.2013.09.010

Summarized in a single table the pregnancy safety data for commonly used topical and oral dermatologic medications, using international classifications.

Pregnancy and postpartum

Butler DC, Heller MM, Murase JE · Journal of the American Academy of Dermatology · doi:10.1016/j.jaad.2013.09.009

Reviewed data on the transfer of dermatologic medications and active ingredients into breast milk and their safety during breastfeeding.

Pregnancy and postpartum

Oh J, Byrd AL, Deming C, Conlan S, Kong HH, Segre JA · Nature · doi:10.1038/nature13786

Showed that oily, moist and dry areas host different communities and that a person's microbiome is stable over time.

What is the skin microbiome, and how do you keep it balanced?

Hill C, Guarner F, Reid G, Gibson GR, Merenstein DJ, Pot B ve ark. · Nature Reviews Gastroenterology & Hepatology · doi:10.1038/nrgastro.2014.66

Defined probiotics as live microorganisms that confer a health benefit when administered in adequate amounts.

Probiotics, prebiotics, postbiotics: what's the difference, and what do they do for skin?

Geller L, Rosen J, Frankel A, Goldenberg G · The Journal of Clinical and Aesthetic Dermatology

Showed that a significant portion of adult women with acne report flares in the premenstrual phase.

Your menstrual cycle and your skin: why you break out before your period, and what to do

Chen Y, Lyga J · Inflammation & Allergy - Drug Targets · doi:10.2174/1871528113666140522104422

Explained how chronic stress may be linked to skin aging through inflammatory signals and oxidative stress.

How does stress show up on your skin? Stress acne, itching and cortisol

Petersen B, Wulf HC · Photodermatology, Photoimmunology & Photomedicine · doi:10.1111/phpp.12099

Showed that in real life people apply sunscreen at far below the test amount, which lowers protection.

How do you choose a sunscreen, and how much should you apply? What SPF do you need?

Holmes AD · Journal of the American Academy of Dermatology · doi:10.1016/j.jaad.2013.08.006

Examined increased mite density and associated microorganisms in rosacea, but emphasized that a mechanism by which a microorganism triggers the disease has not yet been shown.

Rosacea

Dessinioti C, Katsambas A · Clinics in Dermatology · doi:10.1016/j.clindermatol.2013.01.001

Reviewed what is known and what remains debated about the causes, risk factors and treatments of seborrheic dermatitis, including the role of yeast.

Seborrheic dermatitis

Schwartz JR, Messenger AG, Tosti A, et al. · Acta Dermato-Venereologica · doi:10.2340/00015555-1382

Showed that markers of inflammation, rapid cell turnover and barrier function are disrupted in dandruff and improve with treatment.

Dandruff and itchy scalp

Clavaud C, Jourdain R, Bar-Hen A, et al. · PLoS One · doi:10.1371/journal.pone.0058203

Showed for the first time with molecular methods that dandruff is linked to a disrupted balance between yeast and bacterial communities on the scalp.

Dandruff and itchy scalpStraight hair (Type 1)Curly and coily hair (Type 3–4)Oily scalpSensitive and itchy scalp

Grover C, Khurana A · Indian Journal of Dermatology, Venereology and Leprology · doi:10.4103/0378-6323.116731

Stressed the importance of distinguishing telogen effluvium from female pattern hair loss and that stress can be both a cause and a result.

Hair loss from stress, dieting and after pregnancy

Durdu M, Güran M, Ilkit M · Diagn Microbiol Infect Dis · doi:10.1016/j.diagmicrobio.2013.04.011

Yeast-related folliculitis was found in 49 (18.5%) of 264 folliculitis patients in Adana; the study emphasized that it is often mistakenly treated with antibiotics for months.

Folliculitis and body acne

Thornton MJ · Dermatoendocrinol · doi:10.4161/derm.23872

Reviewed how estrogen deficiency thins the skin, reduces collagen and elasticity, increases dryness and wrinkles, and weakens defenses against oxidative stress.

Skin and hair in menopause40s50s

Sundelin T, Lekander M, Kecklund G, Van Someren EJ, et al. · Sleep · doi:10.5665/sleep.2964

Showed that the faces of sleep-deprived people were perceived as having puffier eyes, darker under-eye circles and more fine lines.

The eye area: dark circles, puffiness and eczema

Flament F, Bazin R, Laquieze S, Rubert V, Simonpietri E, Piot B · Clin Cosmet Investig Dermatol · doi:10.2147/CCID.S44686

In 298 women aged 30-78, UV exposure was concluded to be responsible for about 80% of visible signs of aging on the face.

Premature aging20s30s

Hughes MC, Williams GM, Baker P, Green AC · Ann Intern Med · doi:10.7326/0003-4819-158-11-201306040-00002

Among 903 adults, the group using sunscreen daily showed 24% less skin aging over 4.5 years than those using it occasionally.

Premature agingNormal skin20s30sHow do you choose a sunscreen, and how much should you apply? What SPF do you need?7 skincare myths: the truth about drinking water, pores and oily skin

Srinivasan G, Srinivas CR, Mathew AC, Duraiswami D · International Journal of Trichology 5(3):137-139 · doi:10.4103/0974-7753.125609

Reported a slight decrease in tensile strength in hair strands washed with hard water, although the difference was not statistically significant.

Dry scalp

Bhate K, Williams HC · British Journal of Dermatology · doi:10.1111/bjd.12149

Reported that about 20% of young people have moderate-to-severe acne, and that acne persists into the 20s in about 64% of individuals and into the 30s in 43%.

Teens

Ali SM, Yosipovitch G · Acta Dermato-Venereologica · doi:10.2340/00015555-1531

Emphasized the importance of skin pH for barrier repair and microbial balance, and the need to consider pH in skincare products.

Damaged skin barrier: 9 signs and how to repair itIs washing your face too much bad? How many times a day should you wash it?

Telang PS · Indian Dermatology Online Journal · doi:10.4103/2229-5178.110593

Emphasized that pure ascorbic acid is unstable and generally needs low-pH formulas to penetrate the skin.

Can you use retinol and vitamin C together? A guide to layering acids, retinol and vitamin C

Kong HH, Oh J, Deming C, ve ark. · Genome Research · doi:10.1101/gr.131029.111

Showed that the proportion of staph rises during flare-ups and is linked to disease severity, and that skin bacterial diversity increases again with treatment.

Atopic dermatitis

Turner GA, Hoptroff M, Harding CR · International Journal of Cosmetic Science · doi:10.1111/j.1468-2494.2012.00723.x

Found that on a scalp with dandruff, structural lipids decrease, water loss increases and sensitivity to irritants rises, and suggested that supporting the barrier may be beneficial.

Seborrheic dermatitisDandruff and itchy scalpOily scalpDry scalpSensitive and itchy scalpScalp care: what causes dandruff and itching, and where does healthy hair begin?

Lee DJ, Lee J, Ha J, Park KC, Ortonne JP, Kang HY · Journal of the European Academy of Dermatology and Venereology · doi:10.1111/j.1468-3083.2011.04337.x

Measured greater water loss and slower barrier recovery after barrier disruption in skin with melasma.

Melasma

Thomas M, Khopkar US · Int J Trichology · doi:10.4103/0974-7753.111215

A study revisiting the relationship of keratosis pilaris with the hair follicle and hair structure.

Keratosis pilaris

Brennan M, Young G, Devane D · Cochrane Database Syst Rev · doi:10.1002/14651858.CD000066.pub2

Noted that pregnancy stretch marks occur in 50-90% of women; across 6 studies including 800 women, no high-quality evidence was found that topical products prevent stretch marks.

Skin during pregnancy and after birth

Sakuma TH, Maibach HI · Skin Pharmacology and Physiology · doi:10.1159/000338978

Summarized that sebum production is influenced by hormones, genetics, age and climate, and that oily skin is associated with enlarged pores and a tendency toward acne.

Oily skin

Bowe WP, Logan AC · Gut Pathogens · doi:10.1186/1757-4749-3-1

Reviewed the gut–brain–skin axis theory, which proposes that stress may affect acne through the gut microbiota and systemic inflammation, and the possible role of probiotics.

AcneHow does stress show up on your skin? Stress acne, itching and cortisol

Lipozencic J, Ljubojevic S · Clinics in Dermatology · doi:10.1016/j.clindermatol.2010.09.007

Summarized the clinical appearance and differential diagnosis of perioral dermatitis and treatment options including metronidazole, azelaic acid and tetracycline-class antibiotics.

Perioral dermatitis

Paul C, Maumus-Robert S, Mazereeuw-Hautier J, ve ark. · Dermatology · doi:10.1159/000334631

Found a dryness prevalence of 55.6% in 756 people over 65; female sex, older age and a history of atopic dermatitis were significant risk factors.

Dryness and barrier damage60 and beyond

Bozzo P, Chua-Gocheco A, Einarson A · Can Fam Physician

Reported that, apart from hydroquinone, which has relatively high systemic absorption, and tretinoin, whose evidence is debated, most skincare products act locally and very little reaches the bloodstream.

Skin during pregnancy and after birth

Elias J, Bozzo P, Einarson A · Can Fam Physician

Stated that probiotics are rarely absorbed systemically in healthy people, that third-trimester studies showed no increase in adverse fetal outcomes, and that passage into breast milk is unlikely.

Skin during pregnancy and after birth

Grice EA, Segre JA · Nature Reviews Microbiology · doi:10.1038/nrmicro2537

Showed that oily areas such as the T-zone of the face and dry areas such as the cheeks host different microbial communities.

Combination skinWhat is the skin microbiome, and how do you keep it balanced?

Lee Y, Kim YD, Hyun HJ, Pi LQ, Jin X, Lee WS · Annals of Dermatology 23(4):455-462 · doi:10.5021/ad.2011.23.4.455

Showed that using a hair dryer too close to the hair and at high heat increases cuticle damage, while drying from about 15 cm (6 inches) away with constant motion markedly reduces damage.

Straight hair (Type 1)Fine and thinning hairColored, bleached and chemically treated hair (including keratin and perms)

Pierce JS, Abelmann A, Spicer LJ, et al. · Journal of Occupational and Environmental Hygiene 8(11):686-699 · doi:10.1080/15459624.2011.626259

Measured that during the application of some professional keratin straightening products, formaldehyde levels in the room air can exceed occupational exposure limits.

Thick and dense hairColored, bleached and chemically treated hair (including keratin and perms)

Imai T · Okajimas Folia Anatomica Japonica 88(1):1-9 · doi:10.2535/ofaj.88.1

Showed at the electron-microscope level that bleaching treatments disrupt the cuticle layers and the structures within the cortex.

Colored, bleached and chemically treated hair (including keratin and perms)

Bin Saif GA, Ericson ME, Yosipovitch G · Experimental Dermatology 20(12):959-968 · doi:10.1111/j.1600-0625.2011.01389.x

Reviews the nerve-, immune- and barrier-related mechanisms of scalp itch and its most common causes.

Sensitive and itchy scalp

Mukhopadhyay P · Indian Journal of Dermatology · doi:10.4103/0019-5154.77542

Noted that soaps are usually alkaline and that gentle cleansers with a pH close to the skin's may be preferable for sensitive skin.

Is washing your face too much bad? How many times a day should you wash it?

Green AC, Williams GM, Logan V, Strutton GM · Journal of Clinical Oncology · doi:10.1200/JCO.2010.28.7078

Reported a lower incidence of melanoma at long-term follow-up in the group that used sunscreen regularly.

How do you choose a sunscreen, and how much should you apply? What SPF do you need?

Mahmoud BH, Ruvolo E, Hexsel CL, et al. · Journal of Investigative Dermatology · doi:10.1038/jid.2010.95

Showed that visible light also causes pigmentation in darker skin, and that this pigmentation is darker and longer-lasting than that from long-wave UVA.

MelasmaPost-inflammatory dark spots and sun spots

Davis EC, Callender VD · Journal of Clinical and Aesthetic Dermatology

Stressed that treatment should start by controlling inflammation and with sun protection, and that irritating treatments can make spots worse.

Post-inflammatory dark spots and sun spots

Vierkötter A, Schikowski T, Ranft U, Sugiri D, et al. · J Invest Dermatol · doi:10.1038/jid.2010.204

In 400 women, an increase in exposure to traffic-related particles was associated with 20% more pigment spots on the forehead and cheeks.

Premature aging

Axelsson J, Sundelin T, Ingre M, Van Someren EJW, Olsson A, Lekander M · BMJ · doi:10.1136/bmj.c6614

Showed that photos of sleep-deprived people were rated as more tired, less healthy and less attractive.

Sleep and skin health: how does lack of sleep affect your skin?

Kahan V, Andersen ML, Tomimori J, Tufik S · Medical Hypotheses · doi:10.1016/j.mehy.2010.07.018

Proposed that sleep deprivation may affect skin integrity through stress hormones and inflammatory signals.

Sleep and skin health: how does lack of sleep affect your skin?

Kornhauser A, Coelho SG, Hearing VJ · Clinical, Cosmetic and Investigational Dermatology · doi:10.2147/CCID.S9042

Explained the mechanisms of action of hydroxy acids and emphasized that AHAs can increase the skin's sensitivity to the sun.

Can you use retinol and vitamin C together? A guide to layering acids, retinol and vitamin C

Brown SJ, Relton CL, Liao H, Zhao Y, et al. · Br J Dermatol · doi:10.1111/j.1365-2133.2009.09339.x

In 792 children, filaggrin gene changes were shown to be strongly associated with findings such as keratosis pilaris, dry skin and eczema.

Keratosis pilaris

Trüeb RM · International Journal of Trichology 1(1):6-14 · doi:10.4103/0974-7753.51923

Reviews how oxidative stress, together with sunlight and environmental factors, plays a role in the aging of the hair shaft and hair follicle.

Colored, bleached and chemically treated hair (including keratin and perms)

Farage MA, Neill S, MacLean AB · Obstetrical & Gynecological Survey · doi:10.1097/OGX.0b013e3181932a37

Summarized many physiological changes over the cycle, including skin sensitivity.

Your menstrual cycle and your skin: why you break out before your period, and what to do

Lundov MD, Moesby L, Zachariae C, Johansen JD · Contact Dermatitis · doi:10.1111/j.1600-0536.2008.01501.x

Reviewed how preservatives are needed to prevent contamination in cosmetics and how infections linked to contaminated products have been reported.

How do you clean makeup brushes? Brush hygiene and removing makeup the right way

Collier CN, Harper JC, Cafardi JA, ve ark. · Journal of the American Academy of Dermatology · doi:10.1016/j.jaad.2007.06.045

50.9% of women aged 20–29 and 35.2% of women aged 30–39 reported acne; rates in women were higher than in men across all adult age groups.

Acne20s30s40s

Proksch E, Brandner JM, Jensen JM · Experimental Dermatology · doi:10.1111/j.1600-0625.2008.00786.x

Explained how the skin barrier is built from protein-rich cells and lipid layers made of ceramides, cholesterol and free fatty acids, and how its disruption sets the stage for disease.

Dryness and barrier damageNormal skinDry skinDamaged skin barrier: 9 signs and how to repair it

Ortonne JP, Bissett DL · Journal of Investigative Dermatology Symposium Proceedings · doi:10.1038/jidsymp.2008.7

Summarized how sun spots and other pigment disorders form, and the targets for treatment.

Post-inflammatory dark spots and sun spots

Baumann L · Dermatologic Clinics · doi:10.1016/j.det.2008.03.007

Proposed a classification that evaluates skin type along the axes of oily–dry, sensitive–resistant, pigmented–non-pigmented and wrinkle-prone–tight.

Combination skin

Nagase S, Tsuchiya M, Matsui T, et al. · Journal of Cosmetic Science 59(4):317-332

Showed that the internal structure and amino acid distribution of curly hair strands differ from straight strands and are asymmetrical.

Wavy hair (Type 2A–2C)Curly and coily hair (Type 3–4)

Misery L, Sibaud V, Ambronati M, et al. · Contact Dermatitis 58(4):234-238 · doi:10.1111/j.1600-0536.2007.01288.x

An epidemiological study in France found that a significant share of participants described sensitive scalp symptoms such as stinging, burning and itching, and that this was reported more often by women.

Sensitive and itchy scalp

Yamasaki K, Di Nardo A, Bardan A, ve ark. · Nature Medicine · doi:10.1038/nm1616

Showed that the defense peptide cathelicidin is abnormally high and processed differently in skin with rosacea, triggering inflammation and blood vessel dilation.

Rosacea

Freitag FM, Cestari TF · J Cosmet Dermatol · doi:10.1111/j.1473-2165.2007.00324.x

Reviewed the multiple causes of dark circles, such as dermal melanin deposits, post-inflammatory pigmentation, swelling, superficial blood vessels and shadowing due to skin laxity.

The eye area: dark circles, puffiness and eczema

Morita A · J Dermatol Sci · doi:10.1016/j.jdermsci.2007.06.015

Reviewed how tobacco smoke disrupts collagen production and increases collagen-degrading enzymes, leading to premature skin aging.

Premature aging

Choi EH, Man MQ, Xu P, Xin S, Liu Z, Crumrine DA ve ark. · Journal of Investigative Dermatology · doi:10.1038/sj.jid.5700913

Showed that from middle age onward the acidity of the skin surface decreases, and that this slows barrier repair.

Mature skin50s60 and beyond

Kafi R, Kwak HS, Schumacher WE, Cho S, Hanft VN, Hamilton TA ve ark. · Archives of Dermatology · doi:10.1001/archderm.143.5.606

A 0.4 percent retinol lotion was seen to reduce fine wrinkles and increase collagen production in aged skin over 24 weeks.

Mature skin60 and beyond

Loussouarn G, Garcel AL, Lozano I, et al. · International Journal of Dermatology 46(s1):2-6 · doi:10.1111/j.1365-4632.2007.03453.x

Introduced a method that classifies hair curl using measures such as curve diameter and number of waves, and showed a wide worldwide range from straight to very tightly coiled hair.

Wavy hair (Type 2A–2C)Curly and coily hair (Type 3–4)

Trüeb RM · Journal der Deutschen Dermatologischen Gesellschaft 5(5):356-365 · doi:10.1111/j.1610-0387.2007.06304.x

Examines, from a dermatological perspective, the effectiveness and possible side effects of the surfactants, conditioning ingredients and preservatives in shampoos.

Fine and thinning hairOily scalpDry scalp

Grimalt R · Journal of Investigative Dermatology Symposium Proceedings 12(2):10-14 · doi:10.1038/sj.jidsymp.5650048

Summarizes, in practical terms, common scalp problems such as dandruff, seborrheic dermatitis, psoriasis and itching, and how to tell them apart.

Dry scalpSensitive and itchy scalp

Smith RN, Mann NJ, Braue A, Mäkeläinen H, Varigos GA · American Journal of Clinical Nutrition · doi:10.1093/ajcn/86.1.107

Showed that in young people aged 15–25, a 12-week low-glycemic-load diet reduced the number of acne lesions more than in the control group.

TeensThe gut-skin connection: how does what you eat affect your skin?

Palmer CNA, Irvine AD, Terron-Kwiatkowski A, ve ark. · Nature Genetics · doi:10.1038/ng1767

Showed that two gene changes that impair the function of the barrier protein filaggrin are a very strong predisposing factor for atopic dermatitis and are found in about 9% of people of European descent.

Atopic dermatitis

Lambers H, Piessens S, Bloem A, Pronk H, Finkel P · International Journal of Cosmetic Science · doi:10.1111/j.1467-2494.2006.00344.x

Showed that the skin's natural surface pH averages 4.7, that skin with a pH below 5 is in better condition in terms of barrier and hydration, and that acidic pH helps beneficial bacteria adhere to the skin.

Perioral dermatitisSensitive skinDryness and barrier damageKeratosis pilarisNormal skinDry skinSensitive skinStraight hair (Type 1)Dry scalpSensitive and itchy scalpWhat is the skin microbiome, and how do you keep it balanced?7 skincare myths: the truth about drinking water, pores and oily skin

Arck PC, Slominski A, Theoharides TC, Peters EM, Paus R · Journal of Investigative Dermatology · doi:10.1038/sj.jid.5700104

Reviewed how the skin and hair follicles are both a target and a source of stress hormones, and the connection between the brain and the skin.

Hair loss from stress, dieting and after pregnancyHow does stress show up on your skin? Stress acne, itching and cortisol

Ambros-Rudolph CM, Müllegger RR, Vaughan-Jones SA, Kerl H, Black MM · J Am Acad Dermatol · doi:10.1016/j.jaad.2005.12.012

Among 505 pregnant women, 49.7% of itchy rashes were atopic eruption of pregnancy, 21.6% were polymorphic eruption of pregnancy and 3% were intrahepatic cholestasis of pregnancy.

Skin during pregnancy and after birth

Amin KA, Belsito DV · Contact Dermatitis · doi:10.1111/j.1600-0536.2006.00927.x

Allergic contact dermatitis was found in 43.8% and seborrheic dermatitis in 36.2% of patients with eyelid eczema; when only the eyelids were involved, seborrheic dermatitis was the most common diagnosis.

The eye area: dark circles, puffiness and eczema

Mukherjee S, Date A, Patravale V, Korting HC, Roeder A, Weindl G · Clin Interv Aging · doi:10.2147/ciia.2006.1.4.327

Reviewed how retinoids provide clinical improvement in photoaging; tretinoin is the strongest, while retinol and retinaldehyde are less irritating.

Premature agingCan you use retinol and vitamin C together? A guide to layering acids, retinol and vitamin C

Draelos ZD, Matsubara A, Smiles K · Journal of Cosmetic and Laser Therapy · doi:10.1080/14764170600717704

A moisturizer containing 2 percent niacinamide was observed to reduce the facial sebum excretion rate over four weeks of use.

Oily skinCombination skin

Farage MA, Katsarou A, Maibach HI · Contact Dermatitis · doi:10.1111/j.0105-1873.2006.00886.x

Reviewed triggers of sensitive skin such as cosmetics, weather and stress, along with sensory, clinical and physiological factors.

Sensitive skin

Varani J, Dame MK, Rittie L, Fligiel SE, et al. · American Journal of Pathology · doi:10.2353/ajpath.2006.051302

Showed that fibroblasts from people aged 18–29 produced markedly more type I procollagen than those from people over 80 (82 vs. 56 ng/ml).

20s30s

Moin A, Jabery Z, Fallah N · International Journal of Dermatology · doi:10.1111/j.1365-4632.2004.02470.x

Found a melasma prevalence of 15.8% in 400 pregnant women; more than half of the cases had a family history of melasma.

Pregnancy and postpartum

Fluhr JW, Feingold KR, Elias PM · Experimental Dermatology · doi:10.1111/j.1600-0625.2006.00437.x

Confirmed that measuring water loss through the skin reliably reflects the state of the barrier.

Damaged skin barrier: 9 signs and how to repair it

Lee SH, Jeong SK, Ahn SK · Yonsei Medical Journal · doi:10.3349/ymj.2006.47.3.293

Summarized how barrier damage triggers the skin's defense and immune responses.

Damaged skin barrier: 9 signs and how to repair it

Weber K, Thurmayr R · Dermatology · doi:10.1159/000084754

Evaluated 30 publications on the treatment of perioral dermatitis and found that only two studies were of moderate quality, while the rest were of low quality.

Perioral dermatitis

Gan DC, Sinclair RD · Journal of Investigative Dermatology Symposium Proceedings · doi:10.1111/j.1087-0024.2005.10102.x

Showed that thinning in the front-central area of the scalp increases with age and affects 57% of women over 80.

Female pattern hair loss

Youn SW, Na JI, Choi SY, Huh CH, Park KC · Skin Research and Technology · doi:10.1111/j.1600-0846.2005.00119.x

Showed that facial sebum decreases markedly from the forehead toward the cheeks and changes with the seasons, proposing a measurable definition of combination skin.

Combination skin

Bissett DL, Oblong JE, Berge CA · Dermatologic Surgery · doi:10.1111/j.1524-4725.2005.31732

5 percent niacinamide was observed to improve fine lines, blotchiness, redness and skin elasticity over 12 weeks.

Mature skin

Keis K, Persaud D, Kamath YK, Rele AS · Journal of Cosmetic Science 56(5):283-295

Showed that coconut oil can penetrate the hair shaft, while mineral oil stays on the surface without getting in.

Curly and coily hair (Type 3–4)Thick and dense hair

Loussouarn G, El Rawadi C, Genain G · International Journal of Dermatology 44(s1):6-9 · doi:10.1111/j.1365-4632.2005.02800.x

Showed through measurements that hair density, growth rate and strand diameter vary markedly across different populations.

Fine and thinning hairThick and dense hair

Olsen EA · Journal of Investigative Dermatology Symposium Proceedings 10(3):217-221 · doi:10.1111/j.1087-0024.2005.10109.x

Discusses the clinical features of female pattern hair thinning and how it is distinguished from other types of hair loss.

Fine and thinning hair

Hall G, Phillips TJ · Journal of the American Academy of Dermatology · doi:10.1016/j.jaad.2004.08.039

Reviewed how declining estrogen is associated with loss of collagen, thickness, elasticity and moisture in the skin, and the effects of hormone therapy on these parameters.

40s50s

Elias PM · Journal of Investigative Dermatology · doi:10.1111/j.0022-202X.2005.23668.x

Showed that the top layer of the skin's functions, such as moisture retention, antimicrobial defense and the acidic surface, are interconnected.

Damaged skin barrier: 9 signs and how to repair it

Dirschka T, Tronnier H, Fölster-Holst R · British Journal of Dermatology · doi:10.1111/j.1365-2133.2004.05985.x

Showed that water loss through the skin is significantly higher in perioral dermatitis than in rosacea and healthy groups and that signs of atopic predisposition are more frequent, defining the condition as a barrier disorder.

Perioral dermatitis

Rawlings AV, Harding CR · Dermatologic Therapy · doi:10.1111/j.1396-0296.2004.04s1005.x

Summarized that the skin's optimal hydration depends on the organization of the lipid layers, the length of the path water travels and natural moisturizing factors.

Dryness and barrier damageDry skinDry skin in winter: central heating, cold air and winter skincare

Ananthapadmanabhan KP, Moore DJ, Subramanyan K, ve ark. · Dermatologic Therapy · doi:10.1111/j.1396-0296.2004.04S1002.x

Showed that harsh surfactants can damage skin proteins and lipids, leading to post-wash tightness, dryness, barrier damage, irritation and itching.

Dryness and barrier damageNormal skinOily skinSensitive skinIs washing your face too much bad? How many times a day should you wash it?7 skincare myths: the truth about drinking water, pores and oily skin

Harding CR · Dermatologic Therapy · doi:10.1111/j.1396-0296.2004.04s1001.x

Explained the brick-and-mortar structure of the skin's top layer, the balance of ceramides, cholesterol and fatty acids, and the role of natural moisturizing factor.

Dry skin

Thiboutot D · Journal of Investigative Dermatology · doi:10.1111/j.1523-1747.2004.t01-2-.x

Explained how oil glands are regulated by hormones, androgens above all.

Oily skin

Yosipovitch G, Sackett-Lundeen L, Goon A, Yiong Huak C, Leok Goh C, Haus E · Journal of Investigative Dermatology · doi:10.1111/j.0022-202X.2004.22313.x

Observed that water loss through the skin was higher in the evening and at night.

Sleep and skin health: how does lack of sleep affect your skin?

Lodén M · American Journal of Clinical Dermatology · doi:10.2165/00128071-200304110-00005

Comprehensively evaluated the role of emollients and moisturizers in dry skin and barrier disorders, and the effects of their ingredients on the barrier.

Dryness and barrier damageDry skinDry skin in winter: central heating, cold air and winter skincare7 skincare myths: the truth about drinking water, pores and oily skin

Rele AS, Mohile RB · Journal of Cosmetic Science 54(2):175-192

Showed that coconut oil applied before and after washing markedly reduced protein loss from the hair shaft compared with mineral oil and sunflower oil.

Curly and coily hair (Type 3–4)Thick and dense hair

Raine-Fenning NJ, Brincat MP, Muscat-Baron Y · American Journal of Clinical Dermatology · doi:10.2165/00128071-200304060-00001

Reviewed how the drop in estrogen at menopause reduces collagen, water-binding glycosaminoglycans and the skin's water content, and noted that hair loss is also associated with this period.

40s

Kroumpouzos G, Cohen LM · American Journal of Obstetrics and Gynecology · doi:10.1067/mob.2003.129

Systematically reviewed the itchy skin conditions specific to pregnancy and emphasized that some require close monitoring for the baby's sake.

Pregnancy and postpartum

Hakozaki T, Minwalla L, Zhuang J, et al. · British Journal of Dermatology · doi:10.1046/j.1365-2133.2002.04834.x

Showed that niacinamide reduced pigment transfer by 35–68% and significantly reduced facial spots after 4 weeks of use.

Post-inflammatory dark spots and sun spots

Rushton DH · Clinical and Experimental Dermatology · doi:10.1046/j.1365-2230.2002.01076.x

Highlighted the link between iron stores and hair loss in women and noted that excessive supplementation without a proven deficiency can lead to hair loss.

Female pattern hair lossHair loss from stress, dieting and after pregnancy

Guin JD · J Am Acad Dermatol · doi:10.1067/mjd.2002.122736

Relevant allergic contact dermatitis was found in 151 (74%) of 203 patients with persistent or recurring eyelid eczema; cosmetics, metals and eye medications were important sources.

The eye area: dark circles, puffiness and eczema

Birch MP, Messenger JF, Messenger AG · British Journal of Dermatology · doi:10.1046/j.1365-2133.2001.04018.x

Showed that female pattern hair loss affects 6% of women under 50 and 38% of those 70 and older, and that hair density averages 293 hairs/cm² at age 35 and 211 hairs/cm² at age 70.

40s60 and beyond

Shah MG, Maibach HI · American Journal of Clinical Dermatology · doi:10.2165/00128071-200102030-00003

Reviewed the link between estrogen and skin hydration, thickness and collagen structure.

Your menstrual cycle and your skin: why you break out before your period, and what to do

Garg A, Chren MM, Sands LP, Matsui MS, Marenus KD, Feingold KR ve ark. · Archives of Dermatology · doi:10.1001/archderm.137.1.53

Showed that the skin barrier's recovery after damage slowed during periods of exam stress.

How does stress show up on your skin? Stress acne, itching and cortisol

Altemus M, Rao B, Dhabhar FS, Ding W, Granstein RD · Journal of Investigative Dermatology · doi:10.1046/j.1523-1747.2001.01373.x

Observed that stress delayed skin barrier repair in healthy women.

How does stress show up on your skin? Stress acne, itching and cortisol

Diffey BL · Journal of the American Academy of Dermatology · doi:10.1067/mjd.2001.117385

Suggested that applying a second layer shortly after going out in the sun may make protection more consistent by reducing gaps in application.

How do you choose a sunscreen, and how much should you apply? What SPF do you need?

Gfatter R, Hackl P, Braun F · Dermatology · doi:10.1159/000245955

Reported that washing with soap raised skin surface pH more noticeably than synthetic detergents.

Is washing your face too much bad? How many times a day should you wash it?

Ghadially R, Brown BE, Sequeira-Martin SM, Feingold KR, Elias PM · Journal of Clinical Investigation · doi:10.1172/JCI117919

Showed that barrier lipids decrease in aged skin and that the barrier recovers much more slowly after damage.

Mature skin60 and beyond

Poskitt L, Wilkinson JD · Br J Dermatol · doi:10.1111/j.1365-2133.1994.tb03406.x

In a follow-up of 49 patients, 80% showed seasonal variation; the most commonly affected area was the arms at 92%, and the average age of improvement was 16.

Keratosis pilaris

Brincat M, Kabalan S, Studd JW, Moniz CF, de Trafford J, Montgomery J · Obstet Gynecol

Showed that postmenopausal skin collagen content, skin thickness and bone mass decrease similarly, by 1-2% per year after menopause.

Skin and hair in menopause50s

Brincat M, Moniz CJ, Studd JW, Darby A, et al. · Br J Obstet Gynaecol · doi:10.1111/j.1471-0528.1985.tb01091.x

Found that in untreated women, skin collagen decreases in relation to the time since menopause, not chronological age.

Skin and hair in menopause

Grove GL, Kligman AM · Journal of Gerontology · doi:10.1093/geronj/38.2.137

Showed that epidermal renewal, which takes about 20 days in young adults, lengthens by more than 10 days in old age, with the decline accelerating especially after 50.

30s50s60 and beyond

Pochi PE, Strauss JS, Downing DT · Journal of Investigative Dermatology · doi:10.1111/1523-1747.ep12532792

Showed that sebum production rises with androgens at puberty, peaks in late adolescence and, in women, gradually declines after menopause.

Teens50s

Shuster S, Black MM, McVitie E · British Journal of Dermatology · doi:10.1111/j.1365-2133.1975.tb05113.x

Showed that skin collagen decreases with age and is lower in women than in men at every age, and that the amount of collagen is directly related to dermal thickness.

20s30s