By definition, a drug is a medicine or substance that exerts a physiologic effect on an organism. In dermatology, medications and substances are utilized on a daily basis from topical treatments to anesthetics in micrographic surgery. The purpose of this section is to focus on some of the more common substances, specifically how they work, how they are utilized, and their routine alternatives. This brief focuses on cyclosporine and its utilization, mechanism of action, efficacy and dosage, adverse effects, special considerations, and alternatives in the treatment of psoriasis.