Definition
What is Psoriasis?
Psoriasis is a chronic inflammatory disease in which the immune system speeds up the renewal of skin cells far too much. Normally skin cells renew in about a month, but in psoriasis this drops to a few days. The cells pile up before they have a chance to shed, forming red, thick plaques with clear borders covered in silvery-white scales. It's most common on the elbows, knees, scalp, lower back and nails.
Psoriasis isn't contagious. It appears when genetic predisposition combines with environmental triggers; a particular branch of the immune system, especially the pathway working through messenger substances called IL-17 and IL-23, becomes overactive. This inflammation may not stay in the skin alone: some people with psoriasis develop psoriatic arthritis, which affects the joints; the risk of cardiovascular disease, metabolic syndrome and depression may also increase. That's why psoriasis today is treated as an inflammatory disease that concerns the whole body, beyond being a “skin disease.”
Psoriasis comes and goes; flare-ups and calm periods follow each other. There's no definitive cure, but thanks to a wide range of treatments, from creams in mild cases to targeted biologic medications in severe ones, plaques decrease noticeably in most people and long calm periods can be achieved. Regular moisturizing and knowing your triggers are the parts of this plan you can put into practice every day.
Check yourself
How do you recognise it?
- ✓Raised plaques with clear borders, red or, on darker skin, purple-brown
- ✓Thick, silvery-white scales on top of the plaques
- ✓Location on the elbows, knees, scalp, lower back and around the belly button
- ✓Itching, burning and a feeling of tightness
- ✓Cracking and bleeding in dried-out plaques
- ✓Small pits in the nails, yellowing, thickening or the nail separating from its bed
- ✓Scaly plaques on the scalp that are thicker and more clearly bordered than dandruff
- ✓Shiny red areas without scales in the armpits, under the breasts and in the groin
- ✓Morning joint stiffness, swollen fingers or joint pain
- ✓New plaques forming at sites of trauma such as scratches or wounds
Why it happens
Main causes
01
Genetic predisposition
The risk rises noticeably in people whose mother or father has psoriasis. Many gene regions related to the immune system have been linked to psoriasis.
02
An overactive immune response
The branch of the immune system working through the messenger substances IL-23 and IL-17 becomes overactive. These messengers push skin cells to multiply rapidly and keep inflammation going.
03
Infections
Strep throat in particular can trigger, in some people and mostly in young people, a form of psoriasis with small drop-shaped plaques.
04
Hormones
In some women psoriasis flares at puberty, after giving birth or at menopause. During pregnancy, some women see improvement while others see it get worse.
05
Lifestyle factors
Smoking, heavy drinking and excess weight increase the risk and severity of psoriasis. These factors can also negatively affect the response to treatment.
06
Skin trauma
Scratches, burns, insect bites and friction can cause new plaques to form at the injured site in people prone to psoriasis. This is called the Koebner phenomenon.
In daily life
Triggers that cause flare-ups
Medical approach
Treatment options
01
Topical treatments
In mild to moderate psoriasis, based on your dermatologist's assessment, topical steroids and vitamin D analogs can be used alone or together. Scale-softening creams and tar products can also help thin the plaques. The duration and areas for steroid creams should be decided by your doctor; the face and skin folds are more sensitive.
02
Light therapy
For psoriasis covering large areas, narrowband UVB therapy planned by a dermatologist can reduce inflammation and slow cell turnover. This treatment is given in a hospital or clinic setting with controlled doses.
03
Systemic medications
In moderate to severe psoriasis, oral or injectable medications that regulate the immune system may be chosen. These medications require regular blood tests and medical follow-up.
04
Biologic treatments
Biologic medications that target specific messenger substances in psoriasis's inflammatory pathways have, in recent years, been able to clear plaques at very high rates in severe psoriasis. Your dermatologist decides which treatment is suitable by looking at disease severity and any accompanying conditions.
05
Joints and overall health
If there are signs of psoriatic arthritis, an assessment together with rheumatology is recommended. Monitoring blood pressure, blood sugar, cholesterol and weight is also an important part of managing psoriasis.
06
Barrier care is part of every treatment
Whatever treatment is chosen, regular moisturizing helps soften plaques, reduce itching and make medications easier to tolerate.
Did you know? · Psoriasis
1.92% · According to a global systematic analysis, the prevalence of psoriasis in adults in Western Europe is about 1.92%; the disease is more common in high-income regions with older populations.
Step by step
Care routine for Psoriasis
- 1
A short, lukewarm shower
Limit your shower to 5–10 minutes and use lukewarm water. Hot water and long showers dry out the barrier and increase itching.
- 2
Soap-free cleanser
Instead of soap, use a soap-free, fragrance-free, pH-balanced cleanser. Don't scrub plaques with a loofah or exfoliating mitt.
- 3
The 3-minute rule
After you get out of the shower, while your skin is still damp, apply a rich moisturizer within the first 3 minutes. This helps hold water in the skin.
- 4
The cream your dermatologist recommends
If you use a topical treatment, apply it to the area and in the amount your doctor described.
- 5
Soft clothing
Choose loose, soft cotton fabrics. Tight clothes that rub can trigger new plaques.
Caution
What to avoid, and when to see a doctor?
Avoid these
- ✕Scraping plaques, picking off scales and scratching
- ✕Long, hot showers, harsh soaps and exfoliating mitts
- ✕Smoking and heavy drinking
- ✕Using cortisone creams for long periods or on the face without a doctor's recommendation
- ✕Suddenly stopping treatment without consulting your doctor
- ✕Getting sunburned; uncontrolled sunbathing or tanning beds
- ✕Tight, rubbing and synthetic clothing
- ✕Putting off medical treatment for unproven “miracle” cures
See a dermatologist
- →If you notice thick, scaly plaques with clear borders on your skin
- →If plaques are spreading over a large area of your body or increasing quickly
- →If you have joint pain, swelling or morning stiffness
- →If your nails have started pitting, thickening or separating
- →If you have redness all over your body, fever and chills; this needs urgent assessment
- →If you're planning a pregnancy or are pregnant and want to review the treatments you use
Common misconceptions
Myth or fact?
Myth
Psoriasis is contagious.
Fact
Psoriasis isn't contagious. It doesn't spread to others through touch, swimming pools, towels or close contact; it's a disease related to the immune system.
Myth
Psoriasis is just a skin problem.
Fact
Psoriasis is an inflammatory disease that can affect the whole body. Monitoring your overall health for joint involvement and cardiovascular and metabolic risks is also recommended.
Myth
There's no cure for psoriasis, so there's nothing to do.
Fact
Although psoriasis has no definitive cure, with options ranging from creams to biologic medications, plaques can be reduced noticeably in most people and long calm periods can be achieved.
Popular searches
Most asked about Psoriasis
Your questions
Frequently asked questions
How can I tell psoriasis from eczema?+
Psoriasis plaques usually have sharp borders, are thick and have silvery scales; they're common on the elbows, knees and scalp. Eczema tends to appear more in skin folds, with poorly defined, itchy areas prone to oozing. A dermatologist should make the distinction.
Does psoriasis affect pregnancy?+
Most women with psoriasis have healthy pregnancies. However, some treatments can't be used during pregnancy; if you're planning a pregnancy, review your treatment with your dermatologist in advance.
Does diet affect psoriasis?+
There's no single proven diet for psoriasis. However, excess weight and heavy drinking can make psoriasis worse; a balanced diet, weight control and quitting smoking can have a positive effect on how the disease progresses.
Is the sun good for psoriasis?+
Controlled light therapy is a method used for psoriasis. But sunburn can trigger new plaques. Keep sun exposure short and avoid burning; light therapy should only be done as planned by your dermatologist.
How is scalp psoriasis different from dandruff?+
Scalp psoriasis plaques are thicker than dandruff, have clear borders and silvery scales; they often extend past the hairline onto the forehead and behind the ears. Dandruff appears as thinner, more scattered flakes.
Do probiotics help with psoriasis?+
In a clinical study, people with psoriasis who took oral probiotics saw a greater reduction in disease severity than the placebo group. But this area is still being researched; probiotics don't replace medical treatment, and you should talk to your doctor before starting, especially if you take medication that affects the immune system.
Is psoriasis contagious?+
No, psoriasis isn't contagious. It doesn't spread through touch, in swimming pools, by sharing a towel or by living in the same home. Psoriasis is an inflammatory disease that appears through genetic predisposition and an overreaction of the immune system.
How does psoriasis start?+
Psoriasis often starts with small, red, raised spots covered in scales on the elbows, knees or scalp; over time these spots can merge into plaques. In some people the first sign is small pits or thickening in the nails. A throat infection, intense stress or a skin injury can trigger the first flare.
Which cream helps psoriasis?+
In mild to moderate psoriasis, dermatologists usually recommend cortisone creams, vitamin D derivative creams or a combination of them; creams with salicylic acid or urea can also be used to soften thick scales. The duration and strength of cortisone creams must be decided by your doctor, because uncontrolled use can thin the skin. A fragrance-free moisturizer used every day supports every treatment.
How can I get rid of scalp psoriasis?+
Shampoos and lotions with salicylic acid, tar or cortisone are often used for scalp psoriasis; softening thick scales first and then gently removing them boosts the effect of treatment. Forcing scales off with your nails or a comb can trigger new plaques. For widespread or stubborn scalp psoriasis, your dermatologist may recommend oral or injectable treatments.
Scientific basis
Sources
- 1.National, regional, and worldwide epidemiology of psoriasis: systematic analysis and modelling study
Parisi R, Iskandar IYK, Kontopantelis E, Augustin M, Griffiths CEM, Ashcroft DM · BMJ · 2020 · 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.
- 2.Psoriasis
Griffiths CEM, Armstrong AW, Gudjonsson JE, Barker JNWN · The Lancet · 2021 · 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.
- 3.Pathophysiology, Clinical Presentation, and Treatment of Psoriasis: A Review
Armstrong AW, Read C · JAMA · 2020 · 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.
- 4.Skin Barrier Function in Psoriasis and Atopic Dermatitis: Transepidermal Water Loss and Temperature as Useful Tools to Assess Disease Severity
Montero-Vilchez T, Segura-Fernández-Nogueras MV, Pérez-Rodríguez I, et al. · Journal of Clinical Medicine · 2021 · 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.
- 5.Alteration of the cutaneous microbiome in psoriasis and potential role in Th17 polarization
Chang HW, Yan D, Singh R, et al. · Microbiome · 2018 · 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.
- 6.Microbe-host interplay in atopic dermatitis and psoriasis
Fyhrquist N, Muirhead G, Prast-Nielsen S, et al. · Nature Communications · 2019 · 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.
- 7.Efficacy and Safety of Oral Administration of a Mixture of Probiotic Strains in Patients with Psoriasis: A Randomized Controlled Clinical Trial
Navarro-López V, Martínez-Andrés A, Ramírez-Boscá A, et al. · Acta Dermato-Venereologica · 2019 · 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.
- 8.The human skin microbiome
Byrd AL, Belkaid Y, Segre JA · Nature Reviews Microbiology · 2018 · doi:10.1038/nrmicro.2017.157
Reviewed how the skin microbiome interacts with the immune system and the imbalances seen in inflammatory diseases such as psoriasis.
