Schizophrenia is a distressing and long-term mental illness affecting 1% of the population. Medication has been available since the 1950s and Haloperidol was one of the first antipsychotics to be offered. Despite the introduction of many other antipsychotics it is still very widely used, and it is the antipsychotic most often used to judge the effectiveness of new medications. This review aims to update the knowledge on the clinical trials comparing placebo and haloperidol.
This review contains 21 studies involving a total of 1519 people who were either inpatients or living in the community. Haloperidol has been found to be better than placebo in improving general functioning and some symptoms in the short term (0-6 weeks), and just general functioning in the medium term (greater than six but less than 24 weeks). None of the people in any of these trials have been followed up for longer than 24 weeks. A significant number of people on haloperidol compared to those on placebo suffered from at least one adverse effect, mainly stiffness (dystonia) and movement disorders such as shaking or restlessness (Parkinsonism). In addition six trials containing 307 people found a significant number of people suffered from sleepiness compared to the control. Overall the data from these trials are not good, with many outcomes being presented in a way that does not allow them to be used in this review. Moreover just less than half of those taking haloperidol and slightly more than half of those receiving placebo left the studies early, suggesting that the design of the trial was possibly not acceptable to these participants. In the light of these results it is therefore somewhat surprising that this medication is used so widely as a comparison for new medication.