Can I take Metformin and Semaglutide together?

Why this happens

Both medicines work in different ways to lower blood sugar. Metformin reduces the amount of sugar your liver produces, while semaglutide helps your body release more insulin when you eat. When used together, their effects are additive, meaning they work together to lower blood sugar more than either would alone.

What you should do

It is very common for these two medicines to be prescribed together. However, you should monitor your blood sugar levels regularly as your doctor advises. Learn to recognise the signs of low blood sugar (such as feeling shaky, sweaty, hungry, or dizzy) and always carry a fast-acting sugar source. If you experience severe or persistent stomach upset, speak to your doctor.

Important precautions

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.

History of pancreatitis

Stop taking semaglutide and seek immediate medical help if you experience severe, persistent stomach pain (which may radiate to your back), as this can be a sign of acute pancreatitis.

Thyroid cancer

Do not take semaglutide if you or any of your family have ever had medullary thyroid carcinoma (MTC) or Multiple Endocrine Neoplasia syndrome type 2 (MEN 2). Contact your doctor immediately if you notice a lump or swelling in your neck.

Diabetic retinopathy - semaglutide

If you have diabetic eye disease and use insulin, rapid improvement in blood sugar control can temporarily worsen your vision. Inform your doctor if you notice any vision changes during treatment.

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 semaglutide. Both alcohol and semaglutide can lower your blood sugar levels; combining them increases the risk of severe hypoglycaemia (low blood sugar). Additionally, semaglutide can cause nausea and vomiting, which alcohol may worsen.

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.

Semaglutide must be taken on an empty stomach with a small sip of plain water (no more than 120ml). You must wait at least 30 minutes before eating, drinking anything else, or taking other oral medicines. If you eat or drink too soon, the medicine will not be absorbed properly and will not work.

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.