Antipsychotics are medications used mainly to treat psychosis (a severe mental condition in which a patient loses touch with reality). They do not cure the condition, but help control symptoms such as hallucinations (sensory perceptions of phenomena that are not actually present) and delusions (false beliefs held despite evidence to the contrary).

Antipsychotics are used to treat a variety of disorders, such as schizophrenia (a thought disorder that makes it difficult for patients to distinguish between real and unreal experiences) and schizoaffective disorder (a condition in which a person exhibits signs of both schizophrenia and a mood disorder). They may also be prescribed as mood stabilizers to treat mood disorders.

Antipsychotics were first introduced in the 1950s, and were effective in treating positive symptoms (abnormal thoughts and perceptions), such as delusions, hallucinations and disordered thinking. Newer antipsychotics, called atypical antipsychotics, were introduced in the 1990s and are effective in treating both positive and negative symptoms (the absence of thoughts and behaviors that would otherwise be expected). Examples of negative symptoms include lack of emotion, speech, social interaction and movement.

Antipsychotics work by blocking certain central nervous system receptors for  dopamine, a brain neurotransmitter essential to thought, motivation, short-term memory and some emotions. The newer types of antipsychotics also work by blocking certain receptors for  serotonin, a chemical found in the brain, platelets and the digestive tract that acts as a neurotransmitter.

Common side effects of antipsychotics may include dry mouth, restlessness, muscle rigidity and weight gain. Some side effects can be managed by altering the dosage, by prescribing medications that counteract the side effects, or by switching to a different type of antipsychotic.