Psoriasis is a common skin disorder that produces thick red plaques covered with silvery scales. The most common areas affected are the scalp, elbows, knees, and lower back, although any skin surface may be involved. It can also occur in the nails and body folds.
Psoriasis is not contagious and cannot be passed from person to person. It can, though, occur in members of the same family.
Psoriasis usually begins in early adulthood or later in life. In most people, the rash is limited to a few areas of skin. In severe cases, it can cover large areas of the body. The rash can heal and come back throughout a person's life.
Psoriasis starts as small red bumps, which enlarge and become scaly. The skin appears thick, but may bleed easily if the scales are picked or rubbed off.
In addition, the rash may produce:
Pitted, cracked, crumbly, or loose nails
How Can I Find Out if I Have Psoriasis?
If you have a rash that is not healing, contact your doctor. He or she can evaluate the rash to determine if it is psoriasis.
What Causes Psoriasis?
The exact cause of psoriasis is unknown, but it is believed that a combination of factors contributes to the development of the disease. An abnormality in the immune system causes inflammation in the skin, triggering new skin cells to develop too quickly. Normally, skin cells are replaced every 28 to 30 days. With psoriasis, new cells grow and move to the surface of the skin every three to four days. The buildup of old cells being replaced by new cells creates the silver scales of psoriasis.
What Causes Psoriasis Outbreaks?
No one knows what causes psoriasis outbreaks. The severity and frequency of outbreaks vary with each person. Outbreaks may be triggered by:
Skin injury (for example, cuts, scrapes, or surgery)
How Is Psoriasis Treated?
There are many treatments for psoriasis. Some treatments slow the production of new skin cells while others relieve itching and dry skin. Your doctor will select a treatment plan that is right for you based on the extent of your rash, where it is on your body, your age, your overall health, and other factors. Common treatments include:
Moisturizers (to relieve dry skin)
Coal tar (a common treatment for scalp psoriasis; it may also be used with light therapy for severe cases; available in lotions, shampoos, and bath solutions)
Vitamin D cream (a special form that is ordered by your doctor; Vitamin D in foods and vitamin pills have no effect on psoriasis)
Treatment for moderate-to-severe cases of psoriasis includes:
Light therapy. Ultraviolet light is used to slow the production of skin cells, and is administered under a doctor's care. PUVA is a treatment that combines a medicine called psoralen with exposure to a special form of ultraviolet light.
Methotrexate. This oral drug can cause liver disease and lung problems, so its use is limited to severe cases of psoriasis and people taking this medication are carefully monitored with blood tests. Chest X-rays and occasional liver biopsies may also be needed.
Retinoids. A class of drugs related to Vitamin A, these can be used in cream or gel forms and pills to treat psoriasis. Retinoids can cause serious side effects, including birth defects; therefore, retinoids are not recommended for women who are pregnant or planning to have children.
Cyclosporine. This immunosuppressant drug may be used for very severe psoriasis that has not responded to other treatments. Because it can damage the kidneys and raise blood pressure, regular monitoring is needed.
Biologic therapies. Newer drugs for treating psoriasis include Amevive, Humira, and Enbrel. All of these are given by injection and work by blocking the body's immune system from "kick-starting" an autoimmune disease such as psoriasis. A similar drug, Remicade, is given by IV on a regular basis.