Psoriasis is a skin disease that causes a rash with itchy, scaly patches, most commonly on the knees, elbows, trunk and scalp.
Psoriasis is a common disease that affects around 2 in 100 people in the UK and an estimated 7.5 million people in the U.S. It can start at any age, but most often develops in adults between 20 and 30 years old and between 50 and 60 years old.
Psoriasis can be associated with arthritis, a chronic inflammatory arthritis that affects 30% of patients with psoriasis. Psoriasis can also affect the nails, causing color changes, small pits, crumbling, or loosening.