Can I take Quetiapine and Venlafaxine together?
Drug interaction guide
Originally published 25 Jan 2026
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Taking quetiapine and venlafaxine together can increase the risk of a rare but serious heart rhythm problem called QT prolongation. It may also increase the risk of 'serotonin syndrome' (too much serotonin in the brain) and cause extra drowsiness or dizziness.
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Why this happens
Both drugs can affect the electrical activity of the heart. Additionally, both drugs influence serotonin levels, and their combined sedative effects can lead to increased sleepiness.
What you should do
Back to contentsSpeak to your doctor before taking these together. They may want to perform a heart trace (ECG) to check your heart rhythm. Seek immediate medical help if you feel dizzy, faint, or experience a racing or pounding heartbeat.
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Important precautions
Back to contentsSerotonin Syndrome
Taking these together increases the risk of a rare but life-threatening condition called serotonin syndrome. Seek urgent medical help if you experience high fever, agitation, confusion, or severe muscle stiffness.
Heart Rhythm Disorders (QT Prolongation)
Quetiapine can affect your heart rhythm. You must tell your doctor if you have a history of heart disease or if you experience sudden dizziness, palpitations, or fainting.
High Blood Pressure (Hypertension)
Venlafaxine can significantly increase your blood pressure. Your blood pressure must be monitored regularly, especially if you already have hypertension.
Food and drink warnings
Back to contentsAlcohol
You should avoid or strictly limit alcohol while taking these medicines. Both quetiapine and venlafaxine can cause drowsiness and dizziness; alcohol will significantly increase these effects, making you feel more sleepy and increasing the risk of falls or accidents. Alcohol can also worsen the symptoms of the condition you are being treated for.
Grapefruit juice
Avoid drinking grapefruit juice or eating grapefruit while taking quetiapine. Grapefruit contains compounds that interfere with how your body breaks down this medicine, which can lead to higher levels of quetiapine in your blood and increase the risk of side effects.
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Using other medicines
Back to contentsTaking multiple medicines? Our Medicines Interaction Checker helps you check whether your prescriptions, over-the-counter medicines, and supplements are safe to take together. Simply search for your medicines to see potential interactions and what to do about them.
Disclaimer
This information is for general educational purposes only and should not be relied upon as a substitute for professional medical advice. Always consult your GP, pharmacist, or another qualified healthcare professional before making decisions about your medications. Individual circumstances may vary, and only a healthcare professional who knows your medical history can provide personalised guidance.
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Article history
The information on this page is written and peer reviewed by qualified clinicians.
25 Jan 2026 | Originally published
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