Can I take Metformin and Sertraline together?

Why this happens

Sertraline belongs to a group of medicines called SSRIs, which can change how the body handles glucose and may increase the body's sensitivity to insulin. While the exact way they interact with metformin isn't fully understood, it is known that starting or stopping an antidepressant can cause fluctuations in blood sugar control.

What you should do

You should monitor your blood sugar levels more frequently when starting sertraline or changing your dose. Be aware of the signs of a 'hypo' (low blood sugar), such as feeling shaky, sweaty, hungry, or dizzy. If you notice significant changes in your blood sugar readings, contact your GP or diabetes specialist, as they may need to adjust your metformin dose.

Important precautions

Depression and anxiety disorders

You may experience an increase in suicidal thoughts or the urge to self-harm when first starting sertraline or changing the dose. This is more common in young adults under 25. Contact your doctor or go to hospital immediately if you notice any changes in your mood or behaviour.

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.

Bleeding disorders

Sertraline can increase your risk of bleeding, particularly from the stomach. Use with caution if you take blood-thinning medicines (like warfarin) or anti-inflammatory painkillers (like ibuprofen or aspirin), as this significantly increases the risk of serious bleeding.

Serotonin Syndrome

Sertraline can cause a life-threatening condition called serotonin syndrome, especially if taken with other medicines that affect serotonin (such as triptans, tramadol, or St John's Wort). Seek urgent medical help if you experience agitation, hallucinations, fast heartbeat, or severe muscle stiffness.

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.

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.

Food and drink warnings

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 sertraline. Combining alcohol with this medicine can increase side effects such as drowsiness, dizziness, and impaired coordination. It may also make your depression or anxiety symptoms worse.

Grapefruit juice

Avoid drinking large amounts of grapefruit juice. Grapefruit contains compounds that can increase the levels of sertraline in your blood, which may increase the risk of side effects.

Caffeine (Coffee, Tea, Energy Drinks)

Be cautious with caffeine intake. Sertraline can sometimes make you feel jittery or anxious, and caffeine can worsen these sensations. Additionally, some studies suggest sertraline may slightly increase caffeine levels in the body.

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.

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.

Using other medicines

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.