Priapism resulting from fluphenazine hydrochloride treatment reversed by diphenhydramine

A chronic schizophrenic patient received 30 mg fluphenazine hydrochloride (Prolixin) PO and developed priapism. Urological examination and subsequent urological workup was negative, indentifying fluphenazine hydrochloride as the cause of the priapism. During the period of priapism evaluation, the patient developed a severe extrapyramidal reaction that was treated with diphenhydramine (Benadryl) 50 mg IV push. There was remission of the extrapyramidal reaction in three minutes followed by resolution of the priapism. The rationale for the treatment of antipsychotic drug-induced priapism with anticholinergic drugs is discussed.