The usual treatment for schizophrenia is antipsychotic medication, often in combination with psychological and social support. These include the older (‘typical’ or first generation) drugs such as chlorpromazine and haloperidol, and newer ‘second generation’ or ‘atypical’ drugs such as olanzapine. Antipsychotics can usually reduce the positive symptoms of psychosis in a few weeks, but are less good at helping with negative symptoms and cognitive dysfunction.

It is not clear whether first of second generation antipsychotics are better, but the side effects they cause are different. ‘Typicals’ tend to cause side effects such as movement disorders, whereas ‘atypicals’ can cause weight gain and diabetes. There is a good response in 40–50% of patients, a partial response in 30–40%, and treatment resistance (failure of symptoms to respond satisfactorily after six weeks to two or three different antipsychotics) in 20% of people (treatment resistance). Clozapine is an effective treatment for those who are treatment resistance, but it has the potentially serious side effect of agranulocytosis (lowered white blood cell count) in 1–4% of people who take it, as well as causing weight gain. In addition, is also superior for negative and cognitive symptoms, as well as reducing suicidality and mortality.