A total of 770 participants were involved in the 11 included studies. Data from five included randomised double-blind studies showed beneficial effects of antipsychotics in the treatment of acute and chronic pain. Quantitative analysis of these studies showed a significant reduction of mean pain intensity after administration of the antipsychotic compared to placebo or another active compound, weighted mean difference (WMD) - (95% CI - to -) for the continuous data; and relative risk (RR) (95% CI to ), number needed to treat to benefit (NNT) for the dichotomous data. Nevertheless, the test for heterogeneity was significant for both the continuous data (P = ) and the dichotomous data (P = ). Obviously this makes the calculated NNT less reliable and caution is warranted when interpreting these results.