What is psoriasis?
Psoriasis (say "suh-RY-uh-sus") is a long-term (chronic) skin problem that causes skin cells to grow too quickly, resulting in thick, white, silvery, or red patches of skin.
Normally, skin cells grow gradually and flake off about every 4 weeks. New skin cells grow to replace the outer layers of the skin as they shed.
But in psoriasis, new skin cells move rapidly to the surface of the skin in days rather than weeks. They build up and form thick patches called plaques (say "plax"). The patches range in size from small to large. They most often appear on the knees, elbows, scalp, hands, feet, or lower back. Psoriasis is most common in adults. But children and teens can get it too.
Having psoriasis can be embarrassing, and many people, especially teens, avoid swimming and other situations where patches can show. But there are many types of treatment that can help keep psoriasis under control.
What causes psoriasis?
Experts believe that psoriasis occurs when the immune system overreacts, causing inflammation and flaking of skin. In some cases, psoriasis runs in families.
People with psoriasis often notice times when their skin gets worse. Things that can cause these flare-ups include a cold and dry climate, infections, stress, dry skin, and taking certain medicines.
Psoriasis isn't contagious. It can't be spread by touch from person to person.
What are the symptoms?
Symptoms of psoriasis appear in different ways. Psoriasis can be mild, with small areas of rash. When psoriasis is moderate or severe, the skin gets inflamed with raised red areas topped with loose, silvery, scaling skin. If psoriasis is severe, the skin becomes itchy and tender. And sometimes large patches form and may be uncomfortable. The patches can join together and cover large areas of skin, such as the entire back.
Psoriasis can also affect the fingernails and toenails, causing the nails to pit, change color, and separate from the nail bed.
In some people, psoriasis causes joints to become swollen, tender, and painful. This is called psoriatic arthritis (say "sor-ee-AT-ik ar-THRY-tus").
Symptoms may disappear (go into remission), even without treatment, and then return (flare up).
How is psoriasis diagnosed?
A doctor can usually diagnose psoriasis by looking at the patches on your skin, scalp, or nails. Special tests aren't usually needed.
How is it treated?
Most cases of psoriasis are mild, and treatment begins with skin care. This includes keeping your skin moist with creams and lotions. These are often used with other treatments including shampoos, ultraviolet light, and medicines your doctor prescribes.
In some cases, psoriasis can be hard to treat. You may need to try different combinations of treatments to find what works for you. Treatment for psoriasis may continue for a lifetime.
What can you do at home for psoriasis?
Skin care at home can help control psoriasis. Follow these tips to care for psoriasis:
- Use creams or lotions, baths, or soaks to keep your skin moist.
- Try short exposure to sunlight or ultraviolet (UV) light.
- Follow instructions for skin products and prescribed medicines. It may take a period of trial and error until you know which skin products or methods work best for you. For mild symptoms of psoriasis, some over-the-counter medicines, such as aloe vera, may be soothing.
It's also important to avoid those things that can cause psoriasis symptoms to flare up or make the condition worse. Things to avoid include:
- Skin injury. An injury to the skin can cause psoriasis patches to form anywhere on the body, including the site of the injury. This includes injuries to your nails or nearby skin while trimming your nails.
- Stress and anxiety. Stress can cause psoriasis to appear suddenly (flare) or can make symptoms worse.
- Infection. Infections such as strep throat can cause psoriasis to appear suddenly, especially in children.
- Certain medicines. Some medicines, such as nonsteroidal anti-inflammatory drugs (NSAIDs), beta-blockers, and lithium, have been found to make psoriasis symptoms worse. Talk with your doctor. You may be able to take a different medicine.
- Overexposure to sunlight. Short periods of sun exposure reduce psoriasis in most people, but too much sun can damage the skin and cause skin cancer. And sunburns can trigger flares of psoriasis.
- Alcohol. Alcohol use can cause symptoms to flare up.
- Smoking. Smoking can make psoriasis worse. If you smoke, try to quit.
Studies have not found that specific diets can cure or improve the condition, even though some advertisements claim to. For some people, not eating certain foods helps their psoriasis. Most doctors recommend that you eat a balanced diet to be healthy and stay at a healthy weight.
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The exact cause of psoriasis isn't known.
Doctors believe that the immune system overreacts, causing inflammation and flaking of skin.
Many scientists believe that psoriasis can be inherited. About one-third of people who have psoriasis have one or more family members with the condition.footnote 1 But it isn't clear that genetic factors alone determine whether you get psoriasis.
Psoriasis isn't contagious—it can't be spread by touch from person to person.
There are several types of psoriasis. Symptoms for each type may vary, but the major symptoms are:
- Raised, bright red patches of skin, often covered with loose, silvery scales, usually on the knees, elbows, or low back.
- Tiny areas of bleeding when skin scales are picked or scraped off (Auspitz's sign).
- Mild scaling to thick, crusted plaques on the scalp.
- Itching, especially during sudden flare-ups or when the psoriasis patches are in body folds, such as under the breasts or buttocks.
- Discolored or pitted nails.
Other symptoms of psoriasis may include:
- Similar plaques in the same area on both sides of the body (for example, both knees or both elbows).
- Flare-ups of many raindrop-shaped patches (guttate psoriasis).
- Joint swelling, tenderness, and pain (psoriatic arthritis).
- Psoriasis patches that appear after an injury, such as a cut, a burn, or too much sun. This is called Koebner's phenomenon. Because this response is common, it's important for people with psoriasis to avoid irritating or injuring their skin.
Several other skin conditions have symptoms similar to psoriasis. And some medicine reactions can cause symptoms (such as reddened skin) similar to psoriasis. Talk to your doctor about the medicines you are taking.
Psoriasis is usually a long-term problem. Symptoms tend to come and go in a cycle of flares, when symptoms get worse, and remission, when symptoms improve and go away for awhile. In other cases psoriasis may persist for long periods of time without getting better or worse.
Several things can make symptoms worse, depending on the type of psoriasis. These factors, or triggers, include:
- Dry climates.
- Skin injury.
- Certain medicines.
A few cases of psoriasis may go away without treatment. But it's usually best to treat psoriasis so that it doesn't get worse. If it becomes severe and widespread, it may be much harder to treat.
Mild, moderate, and severe psoriasis
The severity of psoriasis is indicated by the amount of redness and scaling, the thickness of the large areas of raised skin patches (plaques), and the percentage of your skin that is affected.
- Plaques cover a small portion of the body, such as the elbows or knees.
- Plaques cover several large areas. For example, most of the scalp may be affected.
- Any joint pain is mild, but not disabling.
- Plaques tend to be visible to other people.
- Psoriasis on the face.
- Plaques that cover at least 10% of your body.
- Pustular psoriasis with large, fluid-filled plaque and severe scaling.
- Erythrodermic psoriasis with severe inflammation and shedding (sloughing) of the skin.
- Psoriatic arthritis, which includes ongoing joint swelling, tenderness, limitation of range of motion, or joint warmth or redness. Severe cases can result in joint destruction.
Learn more about the different types of psoriasis.
What Increases Your Risk
Many doctors believe that psoriasis may be passed down from parents to their children (inherited). This is because certain genes are found in families who are affected by psoriasis.footnote 2 About one-third of people who have psoriasis have one or more family members with the condition.footnote 1
Other factors that can contribute to the development of psoriasis include:
- Emotional or physical stress. Stress may cause psoriasis to appear suddenly or make symptoms worse (although this has not been proved in studies).
- Infection. Infections such as strep throat can cause psoriasis to appear suddenly, especially in children.
- Skin injuries. An injury to the skin can cause psoriasis patches to form anywhere on the body, including the site of the injury. This includes injuries to your nails or nearby skin while trimming your nails.
- Smoking. Smoking may make you more likely to get psoriasis and make the symptoms more severe.footnote 3
When should you call your doctor?
Call your doctor if you have:
- Symptoms of psoriasis. Early treatment may help keep the condition from getting worse. For more information, see Symptoms.
- Signs of developing bacterial infection. These include:
- Increased pain, swelling, redness, tenderness, or heat.
- Red streaks extending from the area.
- A discharge of pus.
- Fever of 100.4°F (38°C) or higher with no other cause.
If you are currently being treated for psoriasis, call your doctor if you:
- Have severe and widespread psoriasis and your skin is more irritated or inflamed than usual, especially if you have another illness.
- Are taking medicine for psoriasis and have serious side effects, such as vomiting, bloody diarrhea, chills, or a fever.
Who to see
Health professionals who can diagnose and treat psoriasis include:
Exams and Tests
Your doctor can often recognize psoriasis by looking at your skin, scalp, and nails.
Tests aren't usually needed. But one or more of the following tests may be done:
- Biopsy. If it is hard to diagnose the condition by looking at your skin, your doctor may remove a small skin sample and send it to a lab for analysis.
- X-rays. If you have joint pain, X-rays may be taken to look for psoriatic arthritis.
- Blood test. It can help rule out other forms of arthritis.
- Throat culture. If your doctor thinks you may have guttate psoriasis, he or she may want to check for strep throat.
- KOH test. Sometimes this skin test is done to rule out a fungal infection.
Currently there is no cure for psoriasis. But many types of treatment are available, including products applied to the skin, phototherapy, and oral medicines, which can help control psoriasis. Most cases are mild and can be treated with skin products. In some cases, psoriasis can be hard to treat if it is severe and widespread. Most psoriasis returns, even mild forms.
The purpose of treatment is to slow the rapid growth of skin cells that causes psoriasis and to reduce inflammation. Treatment is based on the type of psoriasis you have, its location, its severity, and your age and overall health.
Treatment can also depend on how much you are affected by the condition, either physically (because of factors such as joint pain) or emotionally (because of embarrassment or frustration from a skin rash that may cover a large or visible area of the body). For example, you may get more aggressive treatment if your psoriasis is severe or if the patches frequently upset you.
Most cases are mild and can be treated with:
- Creams, ointments, and lotions to moisturize the skin.
- Shampoos, oils, and sprays to treat psoriasis of the scalp.
- Some exposure to sunlight.
Depending on what type of psoriasis you have, treatment may also include:
- Skin products that your doctor prescribes.
- Pills that your doctor prescribes.
- Shots to help your immune system.
- Phototherapy, which involves exposing your skin to special ultraviolet light.
You may need to try different treatments before you find one that works well for you. It's important to discuss your treatment and progress with your doctor.
Many doctors will recommend that treatments be changed or rotated after a certain period of time to make treatment more effective and to reduce side effects.
People respond differently to psoriasis treatments. A treatment that worked one time may not work again. A treatment that didn't work the first time may work when tried again later.
It's also important to avoid anything that can trigger a flare-up of psoriasis or make the condition worse. Stress, skin injury, infection, and use of alcohol can all contribute to symptom flare-ups. Streptococcal infections, which usually affect the upper respiratory tract, are linked to guttate psoriasis.
Treat scalp or nail psoriasis
Scalp and nail psoriasis can be hard to treat. Both conditions are more likely to improve with medicines taken by mouth (oral medicines). Treatment for the scalp often includes tar shampoos or corticosteroid solutions.
Ask for help
Psoriasis can cause a lot of stress and affect how you feel about yourself. Seek information or counseling from your doctor. For tips on dealing with stress, see Home Treatment. You can also get educational materials and find support networks by contacting the National Psoriasis Foundation at www.psoriasis.org.
There is no way to prevent psoriasis. But you can take steps to improve symptoms or help reduce the number of psoriasis flare-ups. For more information, see Home Treatment.
Most of the time psoriasis can be treated at home. These tips may improve your symptoms or help reduce the number of psoriasis flare-ups:
- Take care of your skin, scalp, and nails. For mild symptoms of psoriasis, various over-the-counter products, such as aloe vera, may be soothing and keep your skin moist.
- Try some of the many psoriasis creams, ointments, and shampoos that you can buy without a prescription. For more information, see Medications.
- Follow your schedule for sunlight or ultraviolet light treatments.
- Be aware of possible medicine reactions. Certain medicines can trigger psoriasis or make symptoms worse.
- Limit alcohol to no more than 2 drinks a day for men or 1 drink a day for women. Alcohol use can cause symptoms to flare up.
- Studies haven't found any "psoriasis diet" that can cure or improve the condition, despite claims over the years. Try to eat a balanced diet and stay at a healthy weight.
What to avoid
Avoid these triggers:
- Cold, dry climates. Cold weather may make symptoms worse. Hot, humid weather and sunlight may improve symptoms. (But hot, humid weather may make certain types of psoriasis worse.)
- Scratching and picking skin. And avoid skin injuries (cuts or scrapes). An injury to the skin can cause psoriasis patches to form anywhere on the body, including the site of the injury. This includes injuries to your nails or nearby skin while trimming your nails.
- Stress and anxiety. Stress may cause psoriasis to appear suddenly (flare). Or it can make symptoms worse, although this has not been proved in studies.
- Infection. Infections such as strep throat can cause one type of psoriasis (called guttate psoriasis) to appear suddenly, especially in children.
- Smoking. Smoking can make your symptoms worse. If you smoke, consider quitting.
Stress and psoriasis
Stress can make your symptoms worse. Some things that can help reduce stress include:
- Practicing relaxation with breathing exercises, yoga, or meditation.
- Getting active. Regular exercise may help you feel better mentally and physically.
- Finding support. To locate a support group in your area, contact the National Psoriasis Foundation online at www.psoriasis.org.
- Learning more about psoriasis. This can help you with your treatment and help you explain your condition to others.
Medicines you put on your skin (topical medicines)
Treatment using more than one topical medicine is often done. This can help prevent side effects from some of the stronger medicines. For example, you may use one medicine during the week but another on the weekend.
- For mild psoriasis, you may be able to control psoriasis using an over-the-counter medicine, including corticosteroid creams. Be safe with medicines. Read and follow all instructions on the label.
- For moderate to severe psoriasis, you may need to use a topical medicine prescribed by your doctor, such as a stronger corticosteroid or a medicine related to vitamin D called calcipotriene. Other topical medicines include anthralin and tars.
Your doctor may have you use occlusion therapy. This means wrapping the skin after applying moisturizers or medicated creams or gels. The wrap can be fabric or plastic. Occlusion keeps the area moist and can make the medicated creams work better. Steroid cream may be used with the occlusion treatment method for small areas, but not for more than a few days. Occlusion of large areas may cause side effects such as thinning of the skin. Talk to your doctor before using occlusion therapy, to make sure that you do it safely.
Pills or shots
Medicines taken by mouth (oral medicines) may be used to treat moderate to severe psoriasis.
Sometimes this type of medicine is given as shots instead of pills.
Medicines called biologics may be used to treat severe psoriasis or psoriasis that hasn't improved after other treatments. Biologics are similar to or the same as proteins made by the body. These medicines block the harmful response of the body's immune system that causes the symptoms of psoriasis.
Some of these medicines are pills and some are given through a needle. Biologics are expensive but work well to treat moderate-to-severe psoriasis. They usually help within a few weeks. A person who takes biologics has a slightly higher risk of getting a serious infection.
Over-the-counter topical medicines
There are many types of nonprescription products, including corticosteroid creams, for psoriasis. Examples of their active ingredients include:
- Salicylic acid, found in products such as Psoriasin Body Wash and Dermasolve e70.
- Coal tar, found in products such as Elta Tar and Neutrogena T/Gel.
These products are used to treat small patches of psoriasis and symptoms, including itching, redness, flaking, and scaling of the skin and scalp. For some people, they may eliminate scales and sores caused by psoriasis.
Topical medicines that a doctor prescribes
- Corticosteroids, which are the most common treatment for psoriasis. Betamethasone is an example of a topical corticosteroid.
- Calcipotriene. This is a form of vitamin D.
- Retinoids, which are medicines related to vitamin A. An example is tazarotene.
- Calcineurin inhibitors, such as pimecrolimus or tacrolimus.
- Anthralin and tars. The use of anthralin and tars has decreased recently, replaced by other medicines such as calcipotriene and tazarotene.
Topical medicines used with ultraviolet (UV) light
- Psoralen and UVA light (called PUVA)
- Tars and UVB light (called Goeckerman treatment)
- Anthralin and UVB light (called the Ingram regimen)
Biologics used to treat psoriasis or psoriatic arthritis include infliximab (Remicade), secukinumab (Cosentyx), and ustekinumab (Stelara).
What to think about
Some medicines used to treat psoriasis can cause serious side effects. You and your doctor will discuss how long to use treatments that could cause harm. You will also need to see your doctor regularly and may have blood tests while using some medicines.
Many oral or injected medicines used to treat psoriasis aren't safe during pregnancy. If you are pregnant, talk to your doctor before taking any medicines.
Surgery isn't used to treat psoriasis of the skin or scalp. But surgery may be used to treat nails that are severely disfigured or damaged from psoriasis. Surgical removal of a nail may be done in a clinic or doctor's office as an outpatient procedure.
Phototherapy uses ultraviolet light to slow the rapid growth of cells that occurs in psoriasis. This treatment can be effective, but your skin should be checked often by your doctor (at least once or twice a year) for any skin damage or skin cancer.
Complementary medicine treatments
Complementary therapies are often used by people with skin diseases, including psoriasis.
These treatments include the use of herbs, vitamins, certain diets, and stress reduction. They may relieve psoriasis symptoms in some people.
Some people notice that natural sunlight and seawater help their psoriasis symptoms. People seeking this treatment may go to seaside resorts, some of which have special programs and medical help for people with psoriasis. For more information, see the website of the National Psoriasis Foundation at www.psoriasis.org.
Current as of
Author: Healthwise Staff
Adam Husney MD - Family Medicine
E. Gregory Thompson MD - Internal Medicine
Martin J. Gabica MD - Family Medicine
Kathleen Romito MD - Family Medicine
Elizabeth T. Russo MD - Internal Medicine
Amy McMichael MD - Dermatology
- Abel EA, Lebwohl M (2012). Psoriasis. In EG Nabel et al., eds., Scientific American Medicine, chap. 48. Hamilton, ON: BC Decker. https://www.deckerip.com/decker/scientific-american-medicine/chapter/48/pdf. Accessed November 21, 2016.
- Puchalsky D (2011). Papulosquamous eruptions—Psoriasis. In ET Bope et al., eds., Conn's Current Therapy 2011, pp. 823–827. Philadelphia: Saunders.
- Fortes C, et al. (2005). Relationship between smoking and the clinical severity of psoriasis. Archives of Dermatology, 141: 1580–1584.
Current as of: April 1, 2019