One of the most common skin diseases, affecting 3 million people in the U.S. alone, psoriasis is the result of an overactive immune system, causing skin cells to multiply too quickly forming scaly patches on the skin.
Mild psoriasis can treated with creams or ointments, while moderate but severe psoriasis may require pills or injections.1
https://www.niams.nih.gov/health-topics/psoriasis