Plaque psoriasis is the most common type of psoriasis. The elbows, knees, scalp, and groin are commonly affected but usually not the face. Generalized psoriasis may involve almost the entire skin surface. Erythrodermic psoriasis may occur after severe sunburn or the use of oral corticosteroids, a medication that is used for the treatment of inflammation. People with erythrodermic psoriasis have widespread redness and scaling of the skin, and itching or pain is also common.
Pustular psoriasis is much rarer.
People with pustular psoriasis have small blisters filled with cloudy fluid, usually pus, maybe only on their palms and soles. Medications, sunlight, pregnancy, infections, emotional stress, and perspiration may all trigger the occurrence of pustular psoriasis. Guttate psoriasis is most commonly triggered by a bacterial or viral respiratory infection. People with guttate psoriasis will see the sudden appearance of very small, round patches of psoriasis on their body. Psoriasis is also one of the few skin diseases in which patches tend to appear at the site of scratches, superficial burns, or even friction.