Methotrexate

In 2003, a 24-year-old woman developed allergic contact dermatitis while receiving treatments for androgenic alopecia, first with minoxidil and then with Serenoa repens (saw palmetto). After using a solution containing minoxidil 4% and tretinoin 0.025% for 10 days, her scalp became erythematous and scaly. The symptoms improved after she stopped using the solution, but recurred upon rechallenge. She was then prescribed a preparation containing Serenoa repens, which led to a recurrence of acute dermatitis on her scalp and generalisation to the rest of her body within 2 weeks. Patch testing showed positive responses to minoxidil 1% and 2%, 'Regaine' 2%, minoxidil 4% with and without tretinoin, the minoxidil/tretinoin solution and the Serenoa repens solution. The authors noted that the patient was probably allergic to the saw palmetto solution, a reaction not previously reported. She was also sensitive to minoxidil, but not retinoic acid.