Inappropriateness of the association of diphenhydramine with diethylcarbamazine for the treatment of lymphatic filariasis.

The efficacy of diphenhydramine, an antihistaminic, in preventing adverse reactions to diethylcarbamazine (DEC) in patients infected with Wuchereria bancrofti, was assessed by treating 50 patients with both drugs and 57 with DEC alone. It was found to be ineffective, and to cause drowsiness in all those unaffected by adverse reactions. The authors conclude that the combined use of both drugs for the treatment of Bancroftian filariasis, which is the usual practice in Brazil, should be avoided.