People with schizophrenia have ‘positive symptoms’ such as hearing voices and seeing things (hallucinations) and fixed strange beliefs (delusions). People with schizophrenia also have ‘negative symptoms’ such as tiredness, apathy and loss of emotion. Antipsychotic drugs are the main treatment for the symptoms of schizophrenia and can be grouped into older drugs (first generation or ‘typical’) and newer drugs (second generation or ‘atypical’). Pimozide is a ‘typical’ antipsychotic drug that was first introduced in the late 1960s and was given to people with schizophrenia. Pimozide is thought to be effective in treating the positive and negative symptoms of schizophrenia or similar mental health problems such as delusional disorder, but it produces serious side effects such as muscle stiffness, tremors and slow body movements. Pimozide may also cause heart problems and has been linked to sudden unexplained death. Monitoring the heart via electrocardiogram is now required before and during treatment with pimozide. It is well known that people with mental health problems suffer from physical illnesses such as heart disease and diabetes and can die on average twenty years younger than those in the general population.
An update search for this review was carried out 28 January 2013; the review now includes 32 studies that assess the effects of pimozide for people with schizophrenia or similar mental health problems. Pimozide was compared with other antipsychotic drugs, placebo (‘dummy’ treatment) or no treatment. Results suggest that pimozide is probably just as effective as other commonly used ‘typical’ antipsychotic drugs (for outcomes such as treating mental state, relapse, leaving the study early). No studies included delusional disorders, so no information is available on this group of people. No evidence was found to support the concern that pimozide causes heart problems (although this may be result of the fact that the studies were small and short term and the participants did not receive doses above recommended limits of 20 mg/d). Pimozide may cause less sleepiness than other typical antipsychotic drugs, but it may cause more tremors and uncontrollable shaking. The claim that pimozide is useful for treating people with negative symptoms also is not supported and proven. However, the quality of evidence in the main was low or very low quality, studies were small and of short duration and were poorly reported. Large‐scale, well‐conducted and well‐reported studies are required to assess the effectiveness of pimozide in the treatment of schizophrenia and other mental health problems such as delusional disorder.