Olanzapine

Olanzapine, sold under the brand name Zyprexa among others, is an atypical antipsychotic primarily used to treat schizophrenia and bipolar disorder. It is also sometimes used off-label for treatment of chemotherapy-induced nausea and vomiting and as an appetite stimulant. For schizophrenia, it can be used for both new-onset disease and long-term maintenance. It is taken by mouth or by injection into a muscle.

Common side effects include significant weight gain, feeling tired, dizziness, constipation, dry mouth, and restlessness. Other side effects include low blood pressure with standing, allergic reactions, neuroleptic malignant syndrome, diabetes mellitus, seizures, and tardive dyskinesia. In older people with dementia, its use increases the risk of death. Use in the later part of pregnancy may result in a movement disorder in the baby for some time after birth. Although its mechanism of action is not entirely clear, it is known to block dopamine and serotonin receptors.

Olanzapine was patented in 1991 and approved for medical use in the United States in 1996. It is available as a generic medication. In 2022, it was the 171st most commonly prescribed medication in the United States, with more than 3 million prescriptions. It is on the World Health Organization's List of Essential Medicines.