Olanzapine

Key facts

• Olanzapine is an atypical antipsychotic used to treat schizophrenia and the manic and depressive episodes of bipolar disorder; it is also combined with fluoxetine for depression that has not responded to other treatment.
• It is taken as tablets or a dissolving wafer, usually once daily; an injectable form treats acute severe agitation in hospital settings.
• Of the commonly used antipsychotics, olanzapine causes the greatest average weight gain, along with raised blood sugar and cholesterol. Weight, blood glucose, and lipid checks are recommended before starting and at intervals afterward.
• Seek urgent care for high fever with muscle stiffness and confusion, or for extreme thirst and frequent urination suggesting very high blood sugar.

What olanzapine treats

Olanzapine treats schizophrenia, easing hallucinations, delusions, and disorganized thinking, and the manic and depressive episodes of bipolar disorder. Combined with fluoxetine, it treats depression that has not improved with other treatments. A fast-acting injectable form is used in hospital settings for acute agitation. It is not intended for occasional use for stress or sleep.

How olanzapine works

Olanzapine blocks dopamine and serotonin receptors in the brain, reducing the overactive signaling behind hallucinations, delusions, and mood extremes. It also affects histamine and other receptors, which adds to its sedating effect and stimulates appetite, driving its weight-gain risk.

Before you take it

• Tell your prescriber about diabetes, high cholesterol, heart disease, or dementia-related confusion before starting.
• Olanzapine typically causes more weight gain than other commonly used antipsychotics, along with raised blood sugar and cholesterol. These should be checked before treatment starts and regularly afterward.
• It is not approved for older adults with dementia-related psychosis, where it raises the risk of stroke and death.
• It adds to the effect of alcohol and other sedating medicines, and can lower blood pressure on standing.

Side effects

Common effects: drowsiness, dry mouth, constipation, dizziness, and increased appetite with weight gain.

Stop and seek urgent medical care for any of these:

• High fever, muscle rigidity, and confusion, possible neuroleptic malignant syndrome.
• Uncontrollable jerking or stiff movements.
• Signs of very high blood sugar: extreme thirst, frequent urination, or unusual fatigue.
• Swelling of the face, lips, or throat, or difficulty breathing.

Safety essentials

• Olanzapine causes more weight gain than most other antipsychotics, along with raised blood glucose and cholesterol. Keep every scheduled weight, blood sugar, and lipid check throughout treatment.
• Its sedating effect can impair driving and is stronger when combined with alcohol or other sedatives.
• Do not stop olanzapine abruptly. Neuroleptic malignant syndrome, a rare but serious reaction causing high fever and severe muscle rigidity, is a medical emergency, and sudden discontinuation can trigger withdrawal or rebound symptoms.

This page is educational and does not replace advice from a doctor or pharmacist who knows your health history.