A Case of Contact Allergic Dermatitis to Topical Minoxidil

The document presents a case of a 27-year-old woman who developed allergic contact dermatitis after using minoxidil 5% foam for female pattern hair loss (FPHL). Minoxidil, initially an oral hypertensive medication, was developed into a topical formulation after observing hypertrichosis in patients. It was approved by the FDA for FPHL treatment in 1992. The most common side effect is irritant contact dermatitis, typically due to an allergic reaction to propylene glycol or, less commonly, minoxidil itself. In this case, the patient developed facial swelling and was advised to avoid topical minoxidil. The document concludes that allergic contact dermatitis to minoxidil is increasingly reported, and patch testing should be considered if patients report itchiness or erythema after applying topical minoxidil. Those allergic to minoxidil itself should not use it for alopecia treatment.