What is psoriasis?

Psoriasis is a long-term (chronic) skin problem that causes skin cells to grow too quickly. This growth causes thick, white, silvery, or red patches of skin (called plaques).

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 quickly to the surface of the skin in days rather than weeks. They build up and form thick plaques. The plaques 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.

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).

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.

Most cases of psoriasis 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. This involves exposing your skin to special ultraviolet light.

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 go on for a lifetime.

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.