Risperidone sold under the trade name Risperdal in the United States, Canada, the United Kingdom and several other countries, Risperdal or Ridal in New Zealand, and Belivon, or Rispen elsewhere) is an atypical antipsychotic medication developed by Janssen Pharmaceutica. It was approved by the United States Food and Drug Administration (FDA) in 1993 for the treatment of schizophrenia. Risperidine contains the functional groups of benzisoxazole and piperidine as part of its molecular structure. In 2003 the FDA approved risperidone for the short-term treatment of the mixed and manic states associated with bipolar disorder. In 2006 the FDA approved risperidone for the treatment of irritability in children and adolescents with autism. Like other atypical antipsychotics, it has also been used 'off-label' for the treatment of anxiety disorders, such as Obsessive-Compulsive disorder; severe, treatment resistant depression with or without psychotic features; Tourette's disorder; disruptive behavior disorders in children; and eating disorders, among others. But use of this drug for treatment of something not approved of such as anxiety could be malpractice because this drug can cause anxiety in its own right as a side effect.

Janssen's patent on Risperdal expires on December 29, 2007, opening the market for cheaper generic versions of the drug from other companies; however, Janssen will continue to have exclusive marketing rights until June 29, 2008, as the result of a pediatric extension.

Risperidone is available as a tablet in 0.25, 0.5, 1, 2, 3 and 4mg sizes, and as a 25 mg, 37.5 mg or 50 mg ampoule Risperdal Consta, is used as a two weekly depot antipsychotic. It is also available as a wafer Risperdal Quicklets.