The coal tar in Psoriasin Multi-Symptom Psoriasis Relief Ointment slows down the excessive skin cell production that is the root cause of psoriasis symptoms. No other FDA compliant non-prescription drug ingredient works this way. The active ingredient in Psoriasin Multi-Symptom Psoriasis Relief Ointment has been recognized to be safe and effective by an FDA expert advisory panel when used as directed./.