Drug interactions in dermatological practice.

Systemic drugs are increasingly used in the treatment of dermatological diseases. Due to the high prevalence of polypharmacy, dermatologists are increasingly faced with the complex problem of drug interaction. Unlike adverse drug reactions, which are often unpredictable, drug interactions can be avoided. This article presents the significant drug interactions that are encountered in clinical practice, with the interactions categorized into those involving antimicrobials, immunosuppressants, antimalarials and colchicine, retinoids and psychiatric medications. There are few commonly used drugs that often cause drug interactions. These include ciclosporin, azole antifungal drugs, erythromycin, sulfonamides and rifampicin, and dermatologists should be alert whenever encountering them. A section on interactions of drugs with health supplements, herbs and food is also included, in view of the increasing use of alternative and complementary therapies in many parts of the world.