Psoriasis is a chronic skin disorder characterized by skin inflammation and flaking that occurs because skin cells grow or turnover too quickly. People affected by psoriasis may also show the following symptoms: thick, red or silvery patches of skin, tender, itchy, dry or cracked skin; thickened, ridged fingernails and toenails, stiff or sore joints (a sign of psoriatic arthritis).
Common types of psoriasis include plaque psoriasis, nail psoriasis, guttate psoriasis, scalp psoriasis, and psoriatic arthritis. Less common types of psoriasis include pustular psoriasis and erythrodermic psoriasis. Various treatments exist for psoriasis, such as light therapies, oral medications, and topical treatments, but there is no cure for psoriasis.