Hypersensitivity syndrome reaction to oral terbinafine

Terbinafine is used extensively to treat onychomycosis and other dermatomycoses. The case of a patient who developed a hypersensitivity syndrome reaction to oral terbinafine is discussed. A 66-year-old male was placed on terbinafine (250 mg/day) for the treatment of onychomycosis. After 4.5 weeks of therapy, the patient developed a cutaneous eruption, pyrexia, lymph-adenopathy and hepatic dysfunction. No infectious or other cause was found for the symptoms and signs, which resolved within 6 weeks of stopping terbinafine. The patient had been on prednisone, doxazosin mesylate and aspirin for several months prior to starting terbinafine. These medications were continued during the episode and subsequently afterwards, with adjustment to the prednisone dosage only. The hypersensitivity syndrome reaction in this case involved multiple systems and was idiosyncratic in nature with no apparent predisposing factors. With the increasing use of oral terbinafine, it is likely that rare adverse events will occur more frequently. It is, therefore, important for physicians to be aware of the possible development of a hypersensitivity syndrome reaction in a patient on terbinafine who experiences an adverse event with multisystem involvement. Prompt recognition and determination of the extent of systemic involvement is important for the proper management of the patient.