Psoriatic arthritis – Some people with psoriasis have psoriatic arthritis. It causes pain, stiffness, and swelling of the joints. It is often mild, but can sometimes be serious and affect many joints. The joint and skin problems don’t always happen at the same time. Your doctor will do a physical exam and imaging tests to diagnose psoriatic arthritis. There is no cure, but medicines can help control inflammation and pain. In rare cases, you might need surgery to repair or replace damaged joints.