A Quick Look at Psoriasis
- Psoriasis at a GlanceAbout 3% of Americans have a long-lasting skin disease called psoriasis. It’s characterized by patches of inflamed, scaly skin, which usually feel itchy or painful. The look of these patches varies, depending on the type of psoriasis you have. The patches can occur on the arms, legs, trunk, scalp, palms, soles of the feet, genitals, and even inside of the mouth. The nails and joints are sometimes affected as well.
- Plaque PsoriasisThis form makes up about 80% of psoriasis cases. Both children and adults are affected. It’s characterized by raised, red patches of skin covered by silvery scales. These patches may itch or feel sore. Plaque psoriasis can occur anywhere on the body, but it’s most often found on the elbows, knees, lower back, and scalp.
- Scalp PsoriasisAt least half of people with plaque psoriasis have a flare-up on their scalp at some point. Scalp psoriasis causes flaking, so it’s easily mistaken for dandruff. Unlike dandruff, however, dry flakes and a silvery sheen are visible on the scalp. Itching is common, but scratching may lead to temporary hair loss. The scalp may also burn or feel sore. Scalp psoriasis can spread to the forehead, the back of the neck, or behind the ears.
- Guttate PsoriasisThis is the second most common form of psoriasis, accounting for about 10% of cases. It causes a rash of small, red, drop-shaped spots on the trunk, arms, legs, or scalp. Guttate psoriasis often starts suddenly after exposure to a trigger—most commonly, strep throat. Other potential triggers include upper respiratory infections, tonsillitis, skin injury, stress, and certain medications.
- Pustular PsoriasisThis form of psoriasis is characterized by white blisters of noninfectious pus surrounded by red skin. The pus is composed of white blood cells. The disease can be localized—limited to certain areas, such as the palms and soles. Or it can be generalized—spread over much of the body. In severe cases affected persons may require hospitalization.
- Inverse PsoriasisThis form of psoriasis causes smooth, red patches of skin. The patches occur in skin folds, such as in the armpits, under the breasts, in the groin, and around the genitals and buttocks. Inverse psoriasis can be worsened by rubbing and sweating. It’s a particular problem for people who are overweight.
- Erythrodermic PsoriasisThis form causes fiery redness and scaling of the skin over most of the body. The scales often come off in sheets rather than small flakes. Other symptoms include intense itching and pain, racing pulse, and changes in body temperature. Erythrodermic psoriasis may be brought on by severe sunburn, infections, and drug reactions. Fluid and electrolyte loss can be serious, so seek medical help immediately.
- Psoriatic NailsAbout half of people with active psoriasis on their skin also have changes in their fingernails or toenails. Psoriasis can also occur on the nails alone. Affected nails often have pits in them. They may be yellow or yellowish-pink in color, sometimes marked with white areas or surrounded by red skin. The nails may loosen, thicken, crumble, or fall off.
- Psoriatic ArthritisUp to 30% of people with psoriasis also develop psoriatic arthritis, an inflammatory disease of the joints. On average, joint disease starts about 10 years after the first signs of psoriasis in the skin. Occasionally, however, the joint disease appears first. Symptoms include swollen, tender joints; back pain; morning stiffness; fatigue; reduced range of motion; psoriatic nails; and redness and pain around the eyes. Left untreated, the arthritis can become disabling, so it’s important to seek medical care promptly.
A Quick Look at Psoriasis