What is psoriasis?

Psoriasis (say "suh-RY-uh-sus") is a long-term skin problem that causes thick, white, silvery, or red patches on the skin. The patches may be small or large, and they occur most often on the knees, elbows, scalp, hands, feet, or lower back.

The skin may be scaly. If the condition is severe, your skin can become itchy and tender. Psoriasis also can be embarrassing if the patches are on visible areas.

You can treat psoriasis with good care at home and with medicine from your doctor. You may put medicine on your skin and take pills or have shots to stop the redness and swelling. Your doctor also may suggest ultraviolet light treatments.

Psoriasis is usually a long-term problem. Symptoms tend to come and go in a cycle. There are flares, when symptoms get worse, and then 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.

A few flare-ups 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.

There are several types of psoriasis. Symptoms for each type may vary, but the major symptoms are:

• Raised, bright red patches of skin (called plaques). They're often covered with loose, silvery scales. They're 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 plaques are in body folds, such as under the breasts or buttocks.
• Discolored or pitted nails.

Other symptoms may include:

• Similar plaques in the same area on both sides of the body.
• Flare-ups of many raindrop-shaped patches (guttate psoriasis).
• Joint swelling, tenderness, and pain (psoriatic arthritis).
• Psoriasis plaques that appear after an injury, such as a cut, a burn, or too much sun.

Symptoms may disappear (go into remission), even without treatment, and then return (flare up).

Most cases of psoriasis are mild. Treatment starts 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. You may need to try different combinations of treatments to find what works for you.

Your doctor can often recognize psoriasis by looking at your skin, scalp, and nails.

Tests usually aren't needed. But one or more of the following tests may be done.

• Biopsy. If it's 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.

Many types of medicines can help control psoriasis. They include:

Medicines you put on your skin (topical).

You may be able to control mild psoriasis with an over-the-counter medicine. These include corticosteroid creams.

For moderate to severe psoriasis, you may need to use a topical medicine prescribed by your doctor. For example, you may need a stronger corticosteroid or a medicine related to vitamin D.

Other topical medicines include anthralin and tars.

Pills or shots.

Medicines you take by mouth may be used to treat moderate to severe psoriasis. Examples are retinoids and methotrexate.

Sometimes this type of medicine is given as shots instead of pills.

Biologics.

These medicines block the harmful response of the body's immune system that causes the symptoms of psoriasis. These may be used to treat severe psoriasis. Or they may be used to treat psoriasis that hasn't improved after other treatments. Examples are infliximab (Remicade) and ustekinumab (Stelara).

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.
• Follow your schedule for sunlight or ultraviolet light treatments.
• Try to eat a balanced diet and stay at a healthy weight.
• Be aware of possible medicine reactions. Certain medicines can trigger psoriasis or make symptoms worse.
• Avoid alcohol if it causes your symptoms to flare up.

You can do things at home to manage your psoriasis. By learning what triggers to avoid, you can improve your symptoms or help reduce the number of psoriasis flare-ups.

Try to 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 at your skin. Also 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.
• Infection. Infections such as strep throat can cause one type of psoriasis (called guttate psoriasis) to appear suddenly, especially in children.
• 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.
• Smoking. Smoking can make your symptoms worse. If you smoke, consider quitting.

Psoriasis is a long-term skin problem that causes skin cells to grow too quickly. This growth causes thick, white, silvery, or red patches of skin (called plaques). They most often appear on the knees, elbows, scalp, hands, feet, or lower back.

The exact cause of psoriasis isn't known. But experts believe that the immune system overreacts, causing inflammation and flaking of skin.

Many scientists believe that psoriasis can be inherited (runs in families). Having certain gene changes can make it more likely for a person to get psoriasis. But it isn't clear that your genes alone determine whether you get psoriasis.

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.

Soak your nails before you trim them. Trim them short, and file the edges smooth to avoid injuring them or scratching yourself. Don't cut, tear, or bite the skin around your nails (cuticles). To help protect your nails, apply colorless nail polish. And wear gloves when you work with your hands.