A Case of Allergic Contact Dermatitis Caused by Topical Minoxidil Solution

In 2004, a study reported a case of allergic contact dermatitis caused by the topical application of a 5% minoxidil solution, a systemic antihypertensive agent known to promote hair growth. The subject was a 34-year-old male who had used the solution for 7 days to treat androgenic alopecia, and presented with a diffuse erythematous patch on his scalp. The study emphasized the importance of evaluating the ingredients of minoxidil solution when allergic contact dermatitis is suspected, as allergic reactions to propylene glycol, a component of the solution, have been frequently reported. The patient showed positive reactions to 1%, 2%, and 5% minoxidil solution in a patch test.