What Is Psoriasis? A Complete Guide

Psoriasis is a chronic autoimmune condition. It causes skin cells to grow too fast, building up into raised, inflamed patches covered with silvery-white scales. It affects about 7.5 million Americans and 125 million people worldwide. Psoriasis is not contagious and has no cure. But it can be managed well with medications, lifestyle changes, and ongoing medical care.

If you’ve just learned you have psoriasis, or you’re trying to figure out what those itchy, flaky patches are, you’re not alone. Millions of people deal with this condition every day. This guide explains what’s happening in your body, the types of psoriasis, who’s most likely to get it, and what treatments look like right now.

What Happens in Your Body When You Have Psoriasis?

In psoriasis, the immune system attacks healthy skin cells by mistake. This triggers rapid overproduction. Normal skin cells take about a month to grow and shed. In psoriasis, that cycle speeds up to just 3 to 4 days. The resulting buildup creates thick, scaly patches called plaques that can appear anywhere on the body.

Your immune system should protect you from infections. With psoriasis, a white blood cell called a T-cell becomes overactive. It starts attacking your own skin. These overactive T-cells release proteins called cytokines that cause inflammation. Key ones include interleukin-17 (IL-17), interleukin-23 (IL-23), and tumor necrosis factor-alpha (TNF-alpha). These cytokines tell skin cells to multiply at a very fast rate.

Healthy skin renews itself about every 28 to 30 days. Old cells shed on their own, and new cells take their place. In psoriasis, immune signals push that timeline down to 3 to 4 days, per the National Psoriasis Foundation. New skin cells pile up faster than old ones can shed. The result is the thick, red, scaly patches that mark psoriasis.

The inflammation doesn’t stop at the skin. Those same cytokines travel through the body. This helps explain why psoriasis is linked to heart disease, type 2 diabetes, and psoriatic arthritis. Psoriasis is a whole-body disease, even though its most visible effects show up on your skin.

What Are the Five Types of Psoriasis?

The five main types of psoriasis are plaque, guttate, inverse, pustular, and erythrodermic. Plaque psoriasis accounts for about 80% to 90% of all cases and appears as raised, red patches with silvery scales. The other types differ in how they look, where they appear, and how severe they are. Some people develop more than one type over time.

Plaque Psoriasis

This is by far the most common form. Plaque psoriasis shows up as clear-edged patches of raised, reddish skin covered with a whitish-silver buildup of dead skin cells (scales). These plaques most often show up on the elbows, knees, lower back, and scalp. But they can form anywhere. They tend to itch, burn, or feel sore. On darker skin tones, plaques may look violet or grayish rather than red. An experienced dermatologist may be needed to spot them.

Guttate Psoriasis

Guttate psoriasis causes small, dot-like spots on the torso, arms, and legs. It most often affects children and young adults. It often follows a strep throat infection. About 8% to 10% of people with psoriasis get guttate psoriasis, per the American Academy of Dermatology. It often follows a strep throat infection. In many cases, guttate psoriasis clears on its own within weeks to months. It can come back or turn into plaque psoriasis.

Inverse Psoriasis

Inverse psoriasis shows up in skin folds: the armpits, under the breasts, in the groin, and between the buttocks. Instead of thick scales, it causes smooth, shiny, red patches that get worse with friction and sweating. Because of where it appears, inverse psoriasis is sometimes mistaken for a fungal infection. It’s more common in people with deep skin folds, including those who carry extra weight.

Pustular Psoriasis

Pustular psoriasis causes white, pus-filled blisters on red or inflamed skin. The pus is not from an infection. It contains white blood cells. This type can stay in one area (usually the palms or soles) or spread across larger parts of the body. Generalized pustular psoriasis can be serious. It may require a hospital stay. It can cause fever, chills, and severe itching.

Erythrodermic Psoriasis

This is the rarest and most severe form. It affects about 2% of people with psoriasis at some point, per the National Psoriasis Foundation. Erythrodermic psoriasis causes redness and skin shedding across most of the body. It can disrupt your body’s ability to control temperature and protect itself. Erythrodermic psoriasis is a medical emergency. It needs immediate treatment.

Who Gets Psoriasis?

Psoriasis affects roughly 3% of U.S. adults, about 7.5 million people. It can start at any age, but most people develop it either between ages 15 and 25 or between 50 and 60. Psoriasis occurs in all racial and ethnic groups, though rates are higher in white populations. Men and women develop it at roughly equal rates.

Psoriasis has two peak ages for diagnosis. The first peak is between ages 15 and 25. The second is between 50 and 60, per the National Institutes of Health. Early-onset psoriasis (before age 40) tends to have a stronger genetic link. It may be more severe over time.

Family history is a big factor. If one parent has psoriasis, their child has about a 10% chance of getting it. If both parents have psoriasis, that risk jumps to about 50%, per the National Psoriasis Foundation.

Researchers have found a genetic marker called HLA-Cw6 (now HLA-C*06:02). It is strongly linked to psoriasis, mainly early-onset plaque psoriasis. About 60% to 65% of people with psoriasis carry this marker. Only about 15% of people overall have it. But having HLA-Cw6 doesn’t mean you’ll get psoriasis. Other genes and triggers from the environment must also line up.

Certain factors can trigger a first episode or cause flare-ups in people who already have psoriasis:

• Infections, especially strep throat (a common trigger for guttate psoriasis)
• Stress, both physical and emotional
• Skin injuries like cuts, scrapes, sunburns, or tattoos (known as the Koebner phenomenon)
• Certain medications, including lithium, beta-blockers, antimalarials, and rapid withdrawal from corticosteroids
• Smoking, which roughly doubles the risk of developing psoriasis and makes existing psoriasis worse
• Heavy alcohol use, which is associated with more severe disease and reduced treatment response
• Cold, dry weather, which tends to worsen symptoms for many people

How Is Psoriasis Different from Eczema?

Psoriasis and eczema both cause red, itchy skin, but they have different causes and patterns. Psoriasis is an autoimmune condition that produces thick, well-defined, scaly plaques. Eczema (atopic dermatitis) comes from a defective skin barrier. It usually causes thinner, less defined, very itchy patches. Eczema is more common in children; psoriasis is more common in adults.

People often confuse psoriasis and eczema because they can look alike, especially on the hands and scalp. Here are the key differences:

Appearance: Psoriasis plaques tend to be thicker with sharper edges. The scales are silvery-white. Eczema patches are usually thinner with softer borders. They may look crusty or weepy.

Location: Psoriasis favors the outside of joints (elbows, knees) and the lower back. Eczema tends to appear inside the joints (inner elbows, behind the knees) and on the face and neck.

Itch quality: Both conditions itch, but eczema tends to produce a more intense itch that can interfere with sleep. Psoriasis can itch too, but burning or stinging sensations are more common.

Onset age: Eczema usually starts in infancy or early childhood. Psoriasis most often appears first in the late teens to mid-20s or after 50.

Cause: Eczema results from skin barrier problems plus immune system overreaction. Psoriasis is mainly driven by T-cell problems and cytokine pathways (IL-17, IL-23, TNF-alpha).

A dermatologist can usually tell them apart on exam. A skin biopsy may be needed in unclear cases. For more detail, see our guide on psoriasis vs. eczema.

What Other Health Conditions Are Linked to Psoriasis?

Psoriasis increases the risk of several other conditions, including psoriatic arthritis (affecting up to 30% of people with psoriasis), cardiovascular disease, type 2 diabetes, metabolic syndrome, depression, and inflammatory bowel disease. These links exist because the same inflammatory pathways that drive psoriasis also affect other organs.

Psoriatic Arthritis

Up to 30% develop psoriatic arthritis (PsA). PsA causes joint pain, stiffness, and swelling, per the National Psoriasis Foundation. PsA can affect any joint. It ranges from mild to severe. Without treatment, it can cause lasting joint damage. Skin symptoms usually come first. But about 15% of people get joint symptoms before any skin changes.

If you notice lasting joint pain, morning stiffness over 30 minutes, or swollen fingers or toes (“sausage digits”), tell your doctor soon. Early treatment with disease-modifying drugs can prevent joint damage.

Cardiovascular Disease

People with moderate to severe psoriasis have higher risk of heart attack, stroke, and irregular heartbeat. A 2017 study in the Journal of the American Heart Association found that severe psoriasis raised the risk of major heart events by 53%. The ongoing inflammation also speeds up plaque buildup in blood vessels (atherosclerosis).

Metabolic Syndrome and Type 2 Diabetes

People with psoriasis are about twice as likely to develop metabolic syndrome. This group includes high blood pressure, high blood sugar, excess belly fat, and abnormal cholesterol levels. The risk of type 2 diabetes is also higher, especially in people with severe psoriasis. This finding comes from a review in the Archives of Dermatological Research.

Depression and Mental Health

Psoriasis takes a real toll on mental health. Research in JAMA Dermatology found that people with psoriasis have a 39% higher risk of depression. They also have a 31% higher risk of anxiety. The visible nature of the disease, social stigma, and chronic discomfort all play a part. If you feel lasting sadness, loss of interest in activities, or isolation, talk to your doctor. Depression in psoriasis is common and treatable. You should not push through it alone.

Other Associated Conditions

People with psoriasis also face higher risk of inflammatory bowel disease (Crohn’s disease and ulcerative colitis). They also have higher risk of fatty liver disease, kidney disease, and certain lymphomas. Regular checkups beyond your skin doctor visits are a key part of managing psoriasis.

How Is Psoriasis Treated?

Psoriasis treatment depends on severity and type. Mild psoriasis may respond to creams and ointments (corticosteroids, vitamin D analogs). Moderate to severe psoriasis often needs light therapy, oral drugs (methotrexate, apremilast), or biologic injections. These biologics target specific immune pathways (IL-17, IL-23, or TNF-alpha).

No single treatment works for all people with psoriasis. Your dermatologist will build a plan based on how much skin is affected, where it appears, and how you respond to early treatments.

Topical Treatments

For mild psoriasis (less than 3% of body surface area), medications applied to the skin are usually the first step:

• Corticosteroid creams and ointments reduce inflammation and itching. They come in strengths from mild (hydrocortisone) to potent (clobetasol). Long-term use of strong corticosteroids can thin the skin, so your doctor will monitor usage.
• Vitamin D analogs (calcipotriene, calcitriol) slow skin cell growth.
• Calcineurin inhibitors (tacrolimus, pimecrolimus) work well for sensitive areas like the face and skin folds.
• Coal tar and salicylic acid products help reduce scaling and itching.

Phototherapy

Controlled ultraviolet (UV) light can slow skin cell growth and reduce inflammation. Narrowband UVB therapy is the most common form. It is usually given two to three times per week in a dermatology office. Some people use home UVB units with their doctor’s guidance.

Systemic Medications

When psoriasis affects more than 5% to 10% of the body or doesn’t respond to topical treatments:

• Methotrexate, taken weekly by mouth or injection, reduces the immune response. It requires regular blood tests to check liver function.
• Apremilast (Otezla) is an oral pill that blocks an enzyme called PDE4 involved in inflammation. It has fewer monitoring requirements than methotrexate.
• Cyclosporine suppresses the immune system and works quickly but is usually limited to short-term use because of kidney effects.

Biologic Therapies

Biologics have changed psoriasis treatment over the past 20 years. These medications are proteins derived from living cells that target specific parts of the immune system:

• TNF-alpha inhibitors (adalimumab/Humira, etanercept/Enbrel, infliximab/Remicade, certolizumab/Cimzia)
• IL-17 inhibitors (secukinumab/Cosentyx, ixekizumab/Taltz, brodalumab/Siliq, bimekizumab/Bimzelx)
• IL-23 inhibitors (guselkumab/Tremfya, risankizumab/Skyrizi, tildrakizumab/Ilumya)
• IL-12/23 inhibitor (ustekinumab/Stelara)

Many people on biologics achieve 75% to 90% skin clearance or better. IL-23 inhibitors like risankizumab and guselkumab show strong results in trials. Some patients stay clear with doses just every 8 to 12 weeks. Learn more in our detailed guide to biologics for psoriasis. The choice of biologic depends on your situation, insurance, and how you respond to treatment.

Living with Psoriasis

A psoriasis diagnosis is something you’ll manage long term. But it doesn’t define your life. Many people with psoriasis find that the right treatment, plus some practical changes, lets them live with little disruption.

Work with a dermatologist you trust. If your current treatment isn’t working well enough, say so. Treatment goals have shifted. Clear or almost-clear skin is a realistic target for most people now, not just “better.”

Moisturize consistently. Keeping your skin hydrated cuts down scaling and discomfort. Apply a thick, fragrance-free moisturizer right after bathing to lock in moisture.

Watch your triggers. Track what causes your flare-ups: stress, alcohol, certain foods, or weather changes. Avoiding your personal triggers can cut down how often psoriasis flares.

Take care of your whole health. Because psoriasis raises heart and metabolic risk, keep up regular checkups with your primary care doctor. Check blood pressure, cholesterol, and blood sugar. Stay active and aim for a balanced diet.

Ask for support when you need it. Psoriasis can be isolating. The National Psoriasis Foundation (1-800-723-9166) offers free resources, support groups, and links to others living with the condition. If your skin affects your mood, relationships, or willingness to do things you enjoy, tell your doctor. Read more about managing the emotional side of psoriasis and tips for living well with psoriasis.

Frequently Asked Questions

Is psoriasis contagious?

No. Psoriasis is an autoimmune condition, not an infection. You cannot catch it from touching someone’s skin, sharing towels, or any other form of contact.

Can psoriasis go away on its own?

Some types, like guttate psoriasis, can clear without treatment. Plaque psoriasis, the most common form, is a chronic condition that typically requires ongoing management. Symptoms may come and go, with periods of flare-ups and remission.

Does psoriasis only affect the skin?

No. Psoriasis is a systemic inflammatory disease that increases the risk of psoriatic arthritis, heart disease, type 2 diabetes, depression, and other conditions. The inflammation that causes skin symptoms also affects other parts of the body.

What foods make psoriasis worse?

Research is limited, but some studies suggest that alcohol, processed foods, refined sugar, and red meat may worsen inflammation and trigger flare-ups in some people. A Mediterranean-style diet rich in fruits, vegetables, fish, and olive oil has been associated with less severe psoriasis in observational studies.

Can stress cause psoriasis flare-ups?

Yes. Stress is one of the most commonly reported triggers. Stress activates inflammatory pathways that can worsen psoriasis. Stress-reduction techniques like exercise, meditation, and adequate sleep may help reduce flare frequency.

Is psoriasis hereditary?

Psoriasis has a genetic component. If one parent has psoriasis, a child has about a 10% chance of developing it. If both parents have it, the risk rises to roughly 50%. The gene HLA-Cw6 is strongly associated with plaque psoriasis, but genetics alone don’t determine whether you’ll develop the condition.

How is psoriasis severity measured?

Dermatologists use several scoring systems. The most common is Body Surface Area (BSA): mild psoriasis covers less than 3% of the body, moderate covers 3% to 10%, and severe covers more than 10%. The Psoriasis Area and Severity Index (PASI) score also factors in redness, thickness, and scaling.

Are biologics safe for long-term use?

Clinical data on biologics now spans 15 to 20 years for some medications, and they have generally shown acceptable long-term safety profiles. Because they modify the immune system, biologics may increase the risk of certain infections. Your dermatologist will discuss your individual risk factors and monitor you regularly with lab work.

Sources and References

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3. American Academy of Dermatology. “Psoriasis: Overview.” aad.org/public/diseases/psoriasis
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8. Gelfand, J.M., et al. “Risk of Myocardial Infarction in Patients with Psoriasis.” JAMA, vol. 296, no. 14, 2006, pp. 1735-1741.
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10. Armstrong, A.W., et al. “Psoriasis and Metabolic Syndrome: A Systematic Review and Meta-Analysis.” Journal of the American Academy of Dermatology, vol. 68, no. 4, 2013, pp. 654-662.
11. Nast, A., et al. “German S3-Guideline on the Treatment of Psoriasis Vulgaris, Adapted from EuroGuiDerm.” Journal of the German Society of Dermatology, vol. 19, 2021, pp. 934-985.
12. Gordon, K.B., et al. “Risankizumab Efficacy and Safety in Moderate-to-Severe Plaque Psoriasis: IMMhance Randomized Clinical Trial.” JAMA Dermatology, vol. 156, no. 12, 2020, pp. 1-10.
13. National Psoriasis Foundation. “Causes and Triggers.” psoriasis.org/causes
14. World Health Organization. “Global Report on Psoriasis.” WHO, 2016.
15. Ogdie, A., et al. “Prevalence and Treatment Patterns of Psoriatic Arthritis in the U.S.” Rheumatology, vol. 60, no. 9, 2021.

Psoriasis Daily is strictly a news and information website about psoriasis. It does not provide medical advice, diagnosis, or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.