Olanzapine is an antipsychotic medication used to treat schizophrenia and bipolar disorder. It is usually classed with the atypical antipsychotics, the newer generation of antipsychotics. It appears to have slightly greater effectiveness in treating schizophrenia (especially the negative symptoms) and a lower risk of causing movement disorders than typical antipsychotics. Olanzapine, however, has a higher risk of causing metabolic side effects like weight gain, gynecomastia, impotence and type 2 diabetes than the typical antipsychotics.
Olanzapine is believed to work by antagonizing the dopamine D2 receptor, an effect it shares with most antipsychotics. Like most other atypical antipsychotics, olanzapine also strongly antagonizes the 5-HT2A receptor, which may partially underpin its reduced propensity for causing movement disorders.