background   Schizophrenia and substance abuse often occur together in the same patient. Antipsychotics are frequently prescribed for this group of patients. However, there is doubt about whether these drugs actually have beneficial effect on these patients. Evidence is lacking.
aim   To review our current knowledge concerning the effects of antipsychotics on patients suffering from both schizophrenia and substance abuse.
method   A literature search was conducted using PubMed and PsychLit, using as key words addiction, schizophrenia, dual diagnosis, substance abuse, antipsychotics, neuroleptics, refractoriness, effectiveness, and for each substance cocaïne, cannabis, opiates and alcohol, drug interactions and side effects. We also consulted manuals and articles listed in the bibliographic references of the literature we used.
results   The designs of the articles we studied differed greatly and nearly all the investigations had methodological flaws. Therefore, we cannot draw any firm conclusions. However, several publications indicate that modern antipsychotics (particularly clozapine) have a fairly beneficial effect on the symptoms of both schizophrenia and substance abuse.
conclusion   More systematic research is needed into the effects of antipsychotics in patients suffering from both schizophrenia and substance abuse. There is some evidence that modern antipsychotics have a more favourable effect than classical antipsychotics. Perhaps clozapine should be prescribed more often for patients with this double affliction.