PUVA utilizes two effective psoriasis treatments, psoralen and UVA light. Psoralen makes skin more sensitive to light, and helps the effectiveness of the UVA rays in breaking down and clearing psoriasis. This photochemotherapy treatment is often prescribed when psoriasis does not respond to other topical treatments, or is widespread throughout the body. Approximately 25 treatments over a 2-3 month period are required for maximum results, typically issued 2-3 times per week. The majority of patients—as many as 90%—reported clear skin following PUVA treatment.