Psoriasis

Psoriasis is a chronic, immune-mediated disease that speeds up the skin's life cycle, so cells pile up into raised, scaly patches called plaques. It is not contagious and there is no cure, but for most people it can be well controlled — and sometimes nearly cleared — with today's treatments.

What is psoriasis?

Psoriasis is a long-term (chronic) inflammatory condition in which an overactive immune system tells skin cells to grow far too quickly. Normally a skin cell takes about a month to rise from the deepest layer of the skin to the surface and shed. In psoriasis this process is dramatically accelerated, so cells reach the surface in days and accumulate before they can fall off. The result is the classic plaque: a thickened, raised patch of skin topped with scale (NIH/NIAMS; StatPearls).

Crucially, psoriasis is not a problem of poor hygiene or an infection — it cannot be caught from or spread to another person. It is an immune-mediated disease, sometimes grouped with other systemic inflammatory conditions, and it is associated with inflammation beyond the skin (AAD/NPF).

There are several recognized types:

• Plaque psoriasis (psoriasis vulgaris) — by far the most common form, accounting for the large majority of cases. It causes well-defined, raised plaques with silvery-white scale (StatPearls).
• Guttate psoriasis — small, drop-shaped spots, often appearing suddenly after a streptococcal throat infection, more common in children and young adults.
• Inverse (flexural) psoriasis — smooth, red or discolored patches in skin folds (armpits, groin, under the breasts), usually without heavy scale.
• Pustular psoriasis — white pustules surrounded by inflamed skin; generalized pustular psoriasis is rare and can be a medical emergency.
• Erythrodermic psoriasis — a rare, severe form causing widespread redness and shedding over most of the body; it can be life-threatening and requires urgent care.

In ICD-10 coding, psoriasis falls under L40 (for example, L40.0 for plaque psoriasis and L40.9 for unspecified psoriasis).

What causes psoriasis and who's at risk?

Psoriasis results from a combination of genetic susceptibility and immune dysregulation, switched on by environmental triggers (StatPearls; NIH).

The immune mechanism. Psoriasis is driven largely by a pathway involving immune signaling molecules — chiefly tumor necrosis factor-alpha (TNF-α), interleukin-23 (IL-23), and interleukin-17 (IL-17). These cytokines fuel the rapid skin-cell turnover and inflammation seen in plaques, and they are the precise targets of modern biologic medications.

Genetics. Psoriasis runs in families. Many people with psoriasis have a relative with the condition, and numerous susceptibility genes have been identified, the best established being within the HLA-C region (HLA-Cw6). Genes load the dice, but they are not destiny — a trigger is usually needed to set the disease in motion (StatPearls).

Common triggers that can start or flare psoriasis include:

• Infections, especially streptococcal throat infections (a classic trigger for guttate psoriasis)
• Skin injury — cuts, scrapes, sunburn, or even tattoos can provoke new plaques at the site (the Koebner phenomenon)
• Stress
• Certain medications, including lithium, beta-blockers, antimalarials, and the rapid withdrawal of oral corticosteroids
• Smoking and heavy alcohol use
• Cold, dry weather and lack of sunlight

Who's at risk. Risk factors include a family history of psoriasis, smoking, obesity, and significant stress. Psoriasis can begin at any age but commonly first appears between the late teens and the 30s, with a second smaller peak later in life. It affects all skin tones, though it can look different — and is sometimes underrecognized — in people with darker skin.

Psoriasis affects roughly 3% of US adults — an estimated 7 to 8 million people — making it one of the most common immune-mediated diseases (PMID 24388724; National Health and Nutrition Examination Survey [NHANES] data). Reported prevalence is somewhat higher in White adults and lower in Black, Hispanic, and Asian adults in US survey data, though differences in how the disease presents and is recognized across skin tones may play a role.

What are the symptoms?

The hallmark of plaque psoriasis is raised, well-demarcated patches of skin covered with scale. On lighter skin these often look red or pink with silvery-white scale; on darker skin they may appear violet, brown, or grayish with gray scale, which can make the condition harder to recognize.

Common features include:

• Thick, raised plaques with a sharp border between affected and normal skin
• Silvery, flaky scale that may shed
• Dryness, cracking, and sometimes bleeding (pinpoint bleeding when scale is removed is called the *Auspitz sign*)
• Itching, burning, or soreness — psoriasis can itch, though often less intensely than eczema
• Nail changes — pitting, thickening, crumbling, discoloration, or separation of the nail from the nail bed (onycholysis), seen in a substantial share of patients

Typical locations are the elbows, knees, scalp, and lower back, often in a symmetrical pattern, though plaques can appear anywhere. Inverse psoriasis instead favors skin folds.

Beyond the skin: psoriatic arthritis. A significant minority of people with psoriasis — commonly cited as around one in three — develop psoriatic arthritis (PsA), an inflammatory joint disease causing joint pain, stiffness (often worse in the morning), and swelling, sometimes with a sausage-like swelling of fingers or toes (dactylitis). Skin disease usually appears first, but PsA can occur before or without obvious skin involvement. Untreated, it can cause lasting joint damage, so new joint symptoms should always be reported (AAD/NPF).

The course is typically relapsing and remitting: plaques flare and then quiet down, sometimes for long stretches.

How is psoriasis diagnosed?

There is no single blood test that confirms psoriasis. Diagnosis is usually clinical — a doctor or dermatologist recognizes it from the appearance, the location, and the pattern of the plaques, along with nail changes and personal or family history (StatPearls; AAD).

Skin biopsy. When the diagnosis is uncertain or to distinguish psoriasis from look-alikes such as eczema, fungal infection, or cutaneous lymphoma, a small skin biopsy can be examined under the microscope. Psoriasis shows characteristic features, including thickening of the upper skin layer and collections of immune cells.

Assessing severity. Clinicians grade psoriasis by how much skin is involved and how it affects quality of life:

• Body surface area (BSA): roughly, mild disease covers less than about 3% of the body, moderate 3–10%, and severe more than 10% (one palm ≈ 1% BSA). These thresholds guide treatment choices.
• PASI (Psoriasis Area and Severity Index): a standardized score combining redness, thickness, scale, and area, used widely in specialist care and clinical trials. Treatment goals are often framed as reaching PASI 75/90/100 (a 75%, 90%, or 100% improvement) or near-clear skin.
• Quality-of-life measures such as the DLQI capture the disease's impact on daily living, which can be significant even with limited skin involvement (AAD/NPF).

Screening for related conditions. Because psoriasis is a systemic inflammatory disease, clinicians screen for psoriatic arthritis (asking about joint pain and stiffness) and monitor cardiometabolic health, since psoriasis is associated with a higher likelihood of obesity, type 2 diabetes, high blood pressure, and cardiovascular disease, as well as depression (AAD/NPF; NIH).

How is psoriasis treated?

Treatment is matched to severity and follows a stepwise approach. The aim is to clear or nearly clear the skin, relieve symptoms, and reduce inflammation — and modern therapy makes clear or near-clear skin a realistic goal for many people (AAD/NPF guidelines).

Lifestyle and self-care first

These measures support every treatment plan:

• Moisturize regularly with thick, fragrance-free emollients to soften scale, reduce cracking, and ease itch.
• Avoid known triggers where possible — manage stress, treat infections promptly, and protect skin from injury and sunburn.
• Don't smoke, and limit alcohol, both of which can worsen psoriasis and reduce treatment response.
• Manage weight and cardiometabolic health, which can improve disease and lowers the associated heart and metabolic risks.
• Sensible sunlight in moderation helps some people, but burning makes psoriasis worse.

Over-the-counter (OTC) options

For mild disease, OTC products can help alongside moisturizers:

• Salicylic acid preparations to help lift and soften scale
• Coal tar shampoos, creams, or bath additives, which slow skin-cell growth and reduce scaling and itch (a long-established remedy)
• OTC hydrocortisone 1% for small areas, used short-term

Prescription options

When OTC measures and moisturizers are not enough, prescription treatments are added, roughly in this order:

Topical therapies (first-line for mild-to-moderate disease):

• Topical corticosteroids — the mainstay of topical treatment, available in a range of potencies matched to the body area; the most widely used psoriasis medications.
• Vitamin D analogues — calcipotriene (calcipotriol) and calcitriol, which slow skin-cell growth and are often combined with a steroid.
• Topical retinoid — tazarotene.
• Newer nonsteroidal topicals, which avoid the long-term side effects of steroids: roflumilast cream (a topical PDE-4 inhibitor, FDA-approved for plaque psoriasis) and tapinarof cream (an aryl hydrocarbon receptor agonist), both approved in 2022 and usable on most body areas (Dermatology Times; AJMC).
• Coal tar and anthralin preparations in some cases.

Phototherapy (light therapy): For more widespread disease, narrowband UVB is a well-established, effective option delivered in a clinic or sometimes at home. Other forms include excimer laser for localized plaques and, less commonly today, PUVA (psoralen plus UVA).

Systemic and biologic therapy (moderate-to-severe disease):

• Traditional oral systemics — methotrexate, cyclosporine, and acitretin (an oral retinoid). These require monitoring for liver, kidney, blood, and pregnancy-related risks.
• Oral small molecules — apremilast (a PDE-4 inhibitor) and deucravacitinib (an oral TYK2 inhibitor, FDA-approved in 2022 for moderate-to-severe plaque psoriasis) (Dermatology Times).
• Biologics (injectable), which target the specific cytokines driving the disease and can produce dramatic, durable clearance. Major classes include:
• TNF-α inhibitors — adalimumab, etanercept, infliximab, certolizumab
• IL-17 inhibitors — secukinumab, ixekizumab, brodalumab, bimekizumab
• IL-23 inhibitors — guselkumab, risankizumab, tildrakizumab
• IL-12/23 inhibitor — ustekinumab

Current AAD/NPF guidelines support biologics as highly effective options with a favorable benefit-to-risk ratio for moderate-to-severe disease; choice depends on disease pattern, joint involvement, other health conditions, and patient preference (AAD/NPF Joint Guidelines).

When psoriatic arthritis is present, treatment is coordinated with a rheumatologist, and several systemics and biologics (such as TNF and IL-17 inhibitors) treat both skin and joints.

Can psoriasis be prevented or managed long-term?

Psoriasis cannot currently be prevented or cured, because the genetic and immune basis is built in. But the disease is highly manageable, and long stretches of clear or nearly clear skin are achievable for many people.

Long-term management rests on a consistent plan: using prescribed treatments as directed, sticking with daily moisturizing, and avoiding personal triggers such as smoking, excess alcohol, untreated infections, and skin injury. Because flares often follow stress or illness, managing those proactively helps.

Equally important is treating psoriasis as a whole-body condition. Guidelines recommend attention to cardiovascular and metabolic health — blood pressure, cholesterol, blood sugar, and weight — and to mental health, since depression and anxiety are more common in people with psoriasis. Regular follow-up allows treatment to be stepped up or adjusted as the disease changes (AAD/NPF; NIH).

When should you see a doctor?

See a clinician if you have persistent, scaly patches that don't resolve, if a suspected case of psoriasis is spreading or affecting your scalp, nails, face, or genitals, or if psoriasis is interfering with sleep, work, or quality of life. A dermatologist can confirm the diagnosis and tailor treatment.

Seek prompt or urgent medical care for these red flags:

• New joint pain, stiffness, or swelling — possible psoriatic arthritis, which should be evaluated early to prevent lasting joint damage
• Sudden widespread redness covering most of the body, with shedding, fever, or feeling very unwell — possible erythrodermic psoriasis, a medical emergency
• A sudden outbreak of pustules over large areas with fever or illness — possible generalized pustular psoriasis, also an emergency
• Signs of skin infection — increasing pain, warmth, pus, or fever
• Severe emotional distress or symptoms of depression linked to the condition

Erythrodermic and generalized pustular flares need same-day or emergency evaluation.

What's the outlook (prognosis)?

For most people, the long-term outlook is good. Psoriasis is a lifelong, relapsing-remitting condition rather than a steadily worsening one, and the great majority of people have mild-to-moderate disease that responds well to treatment. Today's options — from improved topicals to phototherapy, oral small molecules, and targeted biologics — mean that clear or nearly clear skin is a realistic goal that was not achievable a generation ago (AAD/NPF; NIH).

The main challenges are the chronic, fluctuating course, the visible nature of the disease and its effect on confidence and mental health, the risk of psoriatic arthritis, and the associated cardiometabolic and cardiovascular risks. Addressing these proactively — with consistent skin treatment, joint screening, attention to heart and metabolic health, and mental-health support — is central to living well with psoriasis. With appropriate care, most people lead full, active lives.

Frequently asked questions

Is psoriasis contagious? No. Psoriasis cannot be caught from or passed to another person through touch, sharing items, or any other contact. It is an immune-mediated disease driven by genetics and the immune system, not by an infection.

What's the difference between psoriasis and eczema? Both cause discolored, scaly patches, but they differ. Psoriasis typically forms thicker, sharply defined plaques with silvery scale on areas like the elbows, knees, scalp, and lower back, and is often only mildly itchy. Eczema is usually intensely itchy, tends to appear in skin creases, and is closely linked to allergies and asthma. A dermatologist can tell them apart, occasionally with a biopsy.

Will my diet cure my psoriasis? No diet cures psoriasis. However, because psoriasis is linked with obesity and cardiometabolic disease, losing excess weight can improve the skin and treatment response, and limiting alcohol may help. A balanced, anti-inflammatory pattern of eating supports overall health, but it is an addition to — not a replacement for — medical treatment.

Does having psoriasis mean I'll get arthritis? Not necessarily, but the risk is meaningful. A notable share of people with psoriasis — commonly cited as roughly one in three — develop psoriatic arthritis. The skin disease usually comes first, sometimes years before joint symptoms, so it's important to report any new joint pain, stiffness, or swelling so it can be treated early.

Can psoriasis go away on its own? Psoriasis can go into remission, sometimes for months or years, and individual plaques can clear. But because the underlying immune and genetic drivers remain, it is considered a lifelong condition that tends to return. Ongoing management keeps it controlled rather than waiting for it to disappear permanently.

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*This page is for general education and is not medical advice. Psoriasis varies from person to person; talk with a qualified healthcare professional about diagnosis and treatment that's right for you.*