Quetiapine

Key facts

• Quetiapine is an atypical antipsychotic used to treat schizophrenia, bipolar disorder, and, at lower doses, as an add-on treatment for major depression.
• It is taken as tablets, once or twice daily for immediate-release, or once daily, usually in the evening, for extended-release.
• Quetiapine commonly causes sedation and metabolic changes: weight gain, raised blood sugar, and raised cholesterol. Regular weight, blood glucose, and lipid checks are recommended before starting and throughout treatment.
• Seek urgent care for high fever with muscle stiffness and confusion, or for a fast, irregular heartbeat.

What quetiapine treats

Quetiapine treats schizophrenia, reducing hallucinations, delusions, and disorganized thinking. It treats the manic and depressive episodes of bipolar disorder, and at low doses it is added to antidepressants for major depression that has not fully responded to those medicines alone. It is sometimes used off-label, short-term, for severe insomnia, but it is not a first-choice sleep aid given its metabolic and sedative effects.

How quetiapine works

Quetiapine blocks dopamine and serotonin receptors in the brain, dampening the overactive signaling linked to hallucinations, delusions, and mood extremes. It also blocks histamine receptors, which adds to its sedating effect, and this mix of receptor actions underlies both its benefits and its tendency to cause drowsiness and weight gain.

Before you take it

• Tell your prescriber about diabetes, high cholesterol, heart disease, or a history of low white blood cell counts before starting.
• Quetiapine causes weight gain and raised blood glucose, triglycerides, and cholesterol in many people. Your prescriber should check your weight, blood sugar, and lipids before you start and at intervals during treatment.
• It causes drowsiness and can drop your blood pressure on standing, so it adds to the effect of alcohol and other sedating medicines.
• It is not approved for older adults with dementia-related psychosis, where it raises the risk of stroke and death.

Side effects

Common effects: drowsiness, dry mouth, constipation, dizziness on standing, 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.
• Fast or irregular heartbeat, or fainting.
• Uncontrollable movements of the face or body.
• Signs of very high blood sugar: extreme thirst, frequent urination, or unusual fatigue.

Safety essentials

• Quetiapine's metabolic effects, weight gain, high blood sugar, and high cholesterol, are common and can appear even without other risk factors. Keep every scheduled weight, glucose, and lipid check throughout treatment.
• Its sedating effect is strongest when starting or increasing the dose; take care with driving and alcohol.
• Do not stop quetiapine abruptly after regular use. Neuroleptic malignant syndrome, a rare but serious reaction causing high fever and severe muscle rigidity, is a medical emergency, and sudden stopping can cause withdrawal or rebound symptoms.

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