Psoriasis is an autoimmune disease that causes raised, red, scaly patches on the skin. Psoriasis is believed to be a hereditary chronic disease.

There are five types of psoriasis and none of the forms of psoriasis are contagious:

  • Plaque psoriasis – the most common form appears as raised, red patches covered with scales. Plaque psoriasis is commonly seen on the scalp, knees, elbows and back.

  • Guttate psoriasis – this form of psoriasis is the second most common type. It appears as small, dot-like lesions that often emerge in childhood or adolescence. It can be triggered by strep infection.

  • Inverse psoriasis – red shiny lesions in body folds such as behind the knees, under the arms or in the groin.

  • Pustular psoriasis – white pustules or blisters surrounded by red skin, most commonly seen on the hands and feet.

  • Erythrodermic psoriasis – this is the most severe form of psoriasis and is very rare. It leads to redness over most of the body and can cause itching and pain and may lead to skin peeling and other complications.

While psoriasis is believed to be hereditary, there are external triggers that can cause the disease to appear such as stress, skin injury, infection and certain medications such as lithium, anti-malarials, indomethacin and beta-blockers. Psoriasis often affects the joints causing psoriatic arthritis and can also be associated with a higher risk of cardiovascular disease.

There are treatment options to help reduce the appearances of plaques and the scaling and itch that may accompany them, these include biologic and systemic medications as well as topical creams, ointments, gels and shampoos.