P21 ALLERGIC CONTACT DERMATITIS TO TOPICAL MINOXIDIL AND PROPYLENE GLYCOL
Schauder S
Department of Dermatology, University of Göttingen, Germany

Topical minoxidil solution has been proven to be a safe and effective treatment for androgenetic alopecia. However, some patients present with complaints of pruritus, burning, erythema, papules, vesicles, and scaling of the scalp, the ears, and the forehead. Sometimes edema in the periorbital region and spreading of the dermatitis to the trunk is noticed. The most common causes of these symptoms include irritant contact dermatitis, allergic contact dermatitis, or an exacerbation of seborrheic dermatitis. This report focuses on 8 women with a history of androgenic alopecia and exposure to Regaine® 5% between 2 days and 9 months in the time period from April 2002 to January 2005. All patients complained of increased pruritus and scaling of the scalp. Three of them developed papules and vesicles on the scalp and the forehead, 2 women presented with periorbital edema and, in 2 patients the dermatitis spread to the trunk. Patch testing resulted in a delayed type allergy to Regaine® 5% and elucidated the specific allergen involved in 7 patients. Four patients demonstrated a positive reaction to propylene glycol and 3 patients to minoxidil, respectively. Although the sensitizing potential of minoxidil is not great compared to propylene glycol, extensive and long term application of minoxidil contributes to the development of contact dermatitis. Unfortunately, patients found to be allergic to minoxidil are no longer candidates for topical treatment of their alopecia with any preparation of minoxidil. Whereas patients with allergic contact dermatitis to propylene glycol may be candidates for treatment with alternative formulations. In September 2000 Regaine® 5% was approved in Germany for androgenetic alopecia in men and in March 2004 Regaine® 2% was approved for women, respectively. With the wide-spread use and the long-term application of minoxidil solution, more patients may develop contact dermatitis to a specific ingredient in the preparation.