People with psoriasis on less than 2 percent of their body are considered to have a mild case. Generally, isolated patches of psoriasis are found on the knees, elbows, scalp and hands and feet. Topical treatments—including moisturizers and over-the-counter and prescription creams, ointments and shampoos—are usually sufficient to keep the psoriasis in check.
Moderate psoriasis is defined as affecting between 2 percent and 10 percent of the body's surface. Psoriasis may appear on the arms, legs, torso, scalp and other areas. Appropriate therapies include topical treatments, phototherapy and oral medications, depending on the location and extent of the psoriasis and other individual factors.
Psoriasis covering more than 10 percent of the body is considered severe. Extensive areas of skin may be covered with psoriasis plaques or pustules, or widespread erythrodermic psoriasis can cause severe peeling of the skin. People with severe psoriasis are more likely to develop psoriatic arthritis. Powerful treatments, including phototherapy, oral medications or a combination of these, are usually necessary to manage severe psoriasis.
