Common side effects include movement problems, sleepiness, dry mouth, low blood pressure upon standing, and increased weight. Serious side effects may include the potentially permanent movement disorder tardive dyskinesia, neuroleptic malignant syndrome, and low white blood cell levels. In older people with psychosis as a result of dementia it may increase the risk of death. It is unclear if it is safe for use in pregnancy. Chlorpromazine is in the typical antipsychotic class. Its mechanism of action is not entirely clear but believed to be related to its ability as a dopamine antagonist. It also has anti-serotonergic and antihistaminergic properties.
Chlorpromazine was discovered in 1950 and was the first antipsychotic. It is on the World Health Organization's List of Essential Medicines, the most effective and safe medicines needed in a health system. Its introduction has been labeled as one of the great advances in the history of psychiatry. It is available as a generic medication. The wholesale cost in the developing world is between US$0.02 and US$0.12 per day. In the United States it costs about US$2 per day.
Chlorpromazine is classified as a low-potency typical antipsychotic and in the past was used in the treatment of both acute and chronic psychoses, including schizophrenia and the manic phase of bipolar disorder, as well as amphetamine-induced psychoses. Low-potency antipsychotics have more anticholinergic side effects, such as dry mouth, sedation, and constipation, and lower rates of extrapyramidal side effects, while high-potency antipsychotics (such as haloperidol) have the reverse profile.
In a 2013 comparison of 15 antipsychotics in schizophrenia, chlorpromazine demonstrated mild-standard effectiveness. It was 13% more effective than lurasidone and iloperidone, approximately as effective as ziprasidone and asenapine, and 12-16% less effective than haloperidol, quetiapine, and aripiprazole.
Chlorpromazine has also been used in porphyria and as part of tetanus treatment. It still is recommended for short-term management of severe anxiety and psychotic aggression. Resistant and severe hiccups, severe nausea/emesis, and preanesthetic conditioning are other uses. Symptoms of delirium in medically-hospitalized AIDS patients have been effectively treated with low doses of chlorpromazine.