Double-blind clinical trials involving the use of phenothiazines as analgesics or potentiators of analgesics (aspirin, meperidine, morphine sulfate) and adverse effects of phenothiazines are reviewed and evaluated. Promethazine, promazine and propiomazine were not found to possess analgesic or potentiating properties. One chlorpromazine study contained important design and reporting deficiencies which precluded a recommendation for use of chlorpromazine in the treatment of pain. Methotrimeprazine was determined by numerous authors to have analgesic properties; however, most of the studies also were deficient in design or data presented, or both. Adverse reactions to phenothiazines, including hypotension, sedation, drowsiness, extrapyramidal symptoms, tardive dyskinesia, cardiac toxicity and agranulocytosis, are often more common and severe than those attributed to narcotic analgesics. Because of the lack of data supportive of analgesic activity and the adverse reactions associated with phenothiazines, use of these agents in the management of pain should be discouraged. The prophylactic use of phenothiazine for narcotic analgesic-induced emesis also is, in most cases, a questionable practice.