Can I take Quetiapine and Venlafaxine together?

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.

Speak 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.

Suicidal thoughts and self-harm

Antidepressants and antipsychotics can increase the risk of suicidal thoughts or self-harm, particularly in the first few weeks of treatment or when the dose is changed. Patients and carers must monitor for any changes in mood or behaviour and seek urgent medical help if these occur.

Serotonin 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)

Both of these medicines can affect your heart rhythm (QT prolongation). This risk is higher when they are taken together or if you have an existing heart condition. You may require regular ECG heart traces.

High Blood Pressure (Hypertension)

Venlafaxine can significantly increase your blood pressure. Your blood pressure must be monitored regularly, especially if you already have hypertension.

Increased bleeding risk

Venlafaxine can increase the risk of bleeding, especially if taken with aspirin, NSAIDs (like ibuprofen), or blood-thinning medicines. Seek medical advice if you notice unusual bruising or persistent bleeding.

Drowsiness and impaired coordination

Quetiapine causes significant drowsiness and can affect your balance. Do not drive or operate machinery until you know how it affects you, and be careful to avoid falls, especially when getting up from a sitting or lying position.

Diabetes and blood sugar control

Quetiapine can cause a significant increase in blood sugar levels, even if you are not diabetic. If you have diabetes, you must monitor your blood sugar more closely as your medication dose may need adjusting.

Dementia in elderly patients

There is an increased risk of stroke and death when quetiapine used to treat dementia-related psychosis in elderly patients.

Alcohol

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.

Caffeine (Coffee, Tea, Energy Drinks)

Caffeine can interfere with how quetiapine works. It may reduce the effectiveness of the medicine or worsen certain side effects like restlessness. If you consume a lot of caffeine, talk to your doctor before making any sudden changes to your intake, as this can also affect your medicine levels.

Limit your intake of caffeine. Venlafaxine can increase blood pressure and heart rate; caffeine can worsen these effects, potentially leading to jitters, anxiety, or palpitations.

High-fat meals

If you are taking the extended-release (XL) version of quetiapine, you should avoid taking it with a very heavy or high-fat meal. This can cause the medicine to be absorbed into your system too quickly (known as 'dose dumping'), which increases the risk of side effects. It is usually best to take it without food or with a light snack.

Taking 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.