Mexiletine-induced severe skin eruption, fever, eosinophilia, atypical lymphocytosis, and liver dysfunction.

A 64-year-old man developed a severe generalized pruritic morbilliform skin eruption, fever, eosinophilia, atypical lymphocytosis, and liver dysfunction 30 days after ingestion of mexiletine, a sodium channel blocker, prescribed to treat postherpetic neuralgia. Following intravenous dexamethasone, body temperature normalized the next day. However, the skin eruption did not disappear completely for 4 weeks. The patch test was positive for mexiletine. Clinical features and the result of patch test indicated that the patient developed hypersensitivity syndrome, a severe adverse cutaneous drug reaction, caused by mexiletine. We propose that mexiletine be added to the list of drugs that can cause severe adverse cutaneous drug reactions and that patients receiving mexiletine be warned to stop taking the drug immediately if a skin eruption occurs.