Is systemic autoimmune disease a risk factor for terbinafine-induced erythema multiforme?

S ir, Terbinafine is a frequently used systemic antimycotic drug, with tinea unguium as its most frequent indication. Most side‐effects are related to the gastrointestinal system (nausea, diarrhoea, taste disorders and hepatitis). Various terbinafine‐induced cutaneous manifestations have been described, including erythema, urticaria, acute generalized exanthematous pustulosis, erythema annulare centrifugum, fixed drug eruption, psoriasis and erythema multiforme (EM). We report three patients who developed EM during treatment with terbinafine (Lamisil®, Novartis) 250 mg daily for onychomycosis. In each case there was a typical clinical presentation of EM with histological confirmation of the diagnosis. Remarkably, each of the three patients had a pre‐existing systemic autoimmune disease. The first patient was a 60‐year‐old man with systemic lupus erythematosus (LE) (anti‐DNA+, SSA+), who had acute cutaneous LE lesions and was being treated with prednisolone 15 mg daily and hydroxychloroquine 400 mg daily. Four weeks after starting terbinafine for onychomycosis, he developed a severe cutaneous eruption that was diagnosed as EM. Terbinafine was stopped and the dose of prednisolone was raised to 40 mg daily. The eruption faded rapidly.