A variety of factors — ranging from emotional stress and trauma to streptococcal infection — can cause an episode of psoriasis. Recent research indicates that some abnormality in the immune system is the key cause of psoriasis. As many as 80% of people having flare-ups report a recent emotional trauma, such as a new job or the death of a loved one. Most doctors believe such external stressors serve as triggers for an inherited defect in immune function.

Injured skin and certain drugs can aggravate psoriasis, including certain types of blood pressure medications (like beta-blockers), the anti-malarial medication hydroxychloroquine, and ibuprofen (Advil, Motrin, etc.).

Psoriasis tends to run in families, but it may be skip generations; a grandfather and his grandson may be affected, but the child’s mother never develops the disease. Although psoriasis may be stressful and embarrassing, most outbreaks are relatively harmless. With appropriate treatment, symptoms generally subside within a few months.