Schizophrenia is a mental illness where the person often experiences both positive symptoms (such as hearing voices, seeing things and having strange beliefs) and negative symptoms (such as tiredness, apathy and loss of emotion). Antipsychotic drugs are used to treat schizophrenia. The antipsychotic drug, haloperidol, is one of the most frequently used drugs worldwide for people with schizophrenia.
The benefits of antipsychotic drugs, such as haloperidol, need to be weighed against their tendency for causing debilitating side effects (such as movement disorders, weight gain, lack of drive) and in some cases an increased likelihood of physical illnesses such as diabetes and heart disease. These debilitating side effects may mean that people stop taking their medication, which can lead to relapse and going into hospital. It is, therefore, important to find a tolerable and effective dose of haloperidol, which helps control the symptoms of schizophrenia but with fewer side effects.
The main aim of this review was to determine the best range of doses of haloperidol for the treatment of schizophrenia. Nineteen trials were included that compared varying doses of haloperidol. Despite over 30 years of trials, data on the effects of differing doses of haloperidol are sparse and poorly reported. This is especially so for the lower dose ranges generally used for the treatment of schizophrenia today. However, lower doses of haloperidol may be just as effective as higher doses but result in fewer side effects. This review also suggests that an important bias against haloperidol may exist in modern trials comparing new drugs with haloperidol. Results are not conclusive and are based on small, short studies of limited quality.
The authors of the review note that it would be understandable if psychiatrists were cautious about prescribing doses above 7.5 mg a day and if people with schizophrenia did not want to take higher dosages. Further research is needed to assess the tolerability and effectiveness of lower doses. Low doses of haloperidol may be just as good as higher doses, but with fewer side effects.