[Fixed drug eruption after taking ethambutol]

Fixed drug eruption (FDE) is a specific skin reaction and the only exclusively medicinal dermatosis. Among the drugs usually responsible are the antituberculous antibiotics including rifampicin and, less often, isoniazid and pyrazinamide. FDE after taking ethambutol is rarely described.

A 32-year old HIV negative patient presented a FDE localized to the internal surface of the lips and the interdigital folds during the 4th month of antituberculous treatment comprising rifampicin, isoniazid and ethambutol. The diagnosis was supported by the characteristic appearances of the lesions of FDE and their early reappearance in the same areas after accidental reintroduction of antituberculous triple therapy including ethambutol. Double-agent therapy with rifamicin and isoniazid was tolerated well.

Discovery of FDE requires a rigorous search for the responsible medicine. During antituberculous treatment, the practitioner has to bear in mind the potential role of ethambutol, which is possibly potentiated by rifampicin.