Risperdal is an atypical antipsychotic used to treat schizophrenia, schizoaffective disorder, bipolar disorder's mixed and manic states, and irritability in patients with autism. Risperdal is the trade name of the drug risperidone, and is marketed and sold by Janssen Pharmaceuticals. A generic form is also available.

Risperdal is available in a variety of forms: a tablet, an oral solution, an injection, and a wafer. The injection form, Risperdal Consta®, is sometimes preferred to treat schizophrenia because it does not require the patient to take their medication every day, thereby possibly increasing medication compliance.

Weight gain and metabolic problems are significant and common side effects of Risperdal. When given at low doses, it has a relatively low incidence of extrapyramidal symptoms (movement disorders), such as akinesia (inability to initiate movement) and akathisia (inability to remain motionless). Unlike many atypical antipsychotics, Risperdal has a more pronounced affect on serotonin than dopamine.