To examine the effects of chlorpromazine for psychosis-induced aggression or agitation.

We searched the Cochrane Schizophrenia Group Trials Register (2008) for randomised control trials or double blind trials implying randomisation, comparing chlorpromazine with another drug or placebo for people thought to be acutely aggressive due to psychotic illness. For selected studies we extracted data and calculated relative risks (RR) and 95% confidence intervals (CI) on an intention-to-treat basis, based on a fixed-effects model.

118 studies were identified, two met inclusion criteria. One compared oral chlorpromazine with oral thioridazine and one intramuscular chlorpromazine with intramuscular haloperidol.Those allocated chlorpromazine did not remain on medication (RR 2.00 CI 0.94 to 4.26), or stay in hospital (RR 1.87 CI 0.70 to 4.95) longer than those allocated thioridazine. No differences were found for adverse effects.Those allocated chlorpromazine were no more likely to have one (RR 3.00 CI 0.13 to 68.26), 2-4 (RR 0.90 CI 0.52 to 1.55) or 5+ (RR 0.75 CI 0.20 to 2.79) injections than those allocated haloperidol. Two patients allocated chlorpromazine had, serious hypotension (RR 5.00 CI 0.26 to 96.13), one developed status epilepticus (RR 3.00 CI 0.13 to 68.26), no one allocated haloperidol had these effects

Overall the quality of evidence is limited and dated. Chlorpromazine was just as effective as similar medicines, but it may be associated with more side effects. Where better, more evaluated drugs are available it may be best to avoid using chlorpromazine. Carefully designed clinical trials are urgently needed.