Can I take Metformin and Quetiapine together?

Why this happens

Quetiapine is an antipsychotic medication that can interfere with how your body processes sugar (glucose metabolism). It can reduce your body's sensitivity to insulin and increase the amount of sugar in your blood. This 'antagonistic' effect opposes the blood-sugar-lowering action of metformin.

You should monitor your blood sugar levels more frequently when starting, stopping, or changing the dose of quetiapine. If you notice your blood sugar readings are consistently high, or if you experience increased thirst or frequent urination, contact your doctor. They may need to adjust your metformin dose or monitor your HbA1c levels more closely.

Suicidal thoughts and self-harm

Quetiapine can increase the risk of suicidal thoughts or self-harm, particularly when first starting the medicine or changing the dose. Monitor your mood closely and seek immediate medical help if your depression worsens or you have thoughts of harming yourself.

Lactic acidosis

Metformin can cause a rare but serious build-up of acid in the blood. Seek urgent medical help if you experience extreme tiredness, muscle pain, or difficulty breathing. This risk is higher if you have severe kidney problems or drink excessive alcohol.

Severe dehydration or infection

If you develop severe vomiting, diarrhoea, or a high fever, you must temporarily stop taking metformin and contact your doctor to prevent kidney strain.

Neuroleptic Malignant Syndrome (NMS) - quetiapine

This is a rare but life-threatening reaction. Seek emergency medical care if you develop a high fever, severe muscle stiffness, confusion, or a rapid heartbeat.

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.

Medical scans using iodine contrast dye

If you are having an X-ray or scan involving an injection of iodine contrast dye, you must stop taking metformin before or at the time of the test to prevent sudden kidney failure.

Alcohol

It is best to avoid or strictly limit alcohol while taking metformin. Drinking alcohol with this medicine increases the risk of a rare but serious condition called lactic acidosis (a build-up of lactic acid in the blood). It also increases the risk of low blood sugar (hypoglycaemia).

It is best to avoid or strictly limit alcohol while taking quetiapine. Combining alcohol with this medicine can significantly increase drowsiness and dizziness, making you more likely to fall or have an accident. Both substances are processed by the liver, and combining them can put extra strain on your system.

Grapefruit juice

Avoid drinking grapefruit juice or eating grapefruit while taking quetiapine. Grapefruit can increase the amount of quetiapine in your blood, which makes side effects more likely.

Vitamin B12 absorption

Long-term use of metformin can prevent your body from absorbing enough vitamin B12 from your food. You may need to have your B12 levels checked by your doctor or take a supplement if you develop symptoms like extreme tiredness or a sore tongue.

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.

General Food Advice

Metformin should be taken with or just after a meal or snack. This helps to reduce the risk of common side effects such as stomach upset, indigestion, or nausea.

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.