Can I take Metformin and Naproxen together?

Why this happens

Naproxen can reduce the blood flow to your kidneys and make it harder for them to clear metformin from your body. If metformin builds up in your system, it increases the risk of lactic acidosis. Additionally, both drugs can put strain on the kidneys, and naproxen may occasionally interfere with how metformin controls your blood sugar.

What you should do

You should speak to your doctor before taking these two medicines together. If your doctor confirms it is appropriate for you, they may want to monitor your kidney function more closely. Seek urgent medical help if you experience symptoms of lactic acidosis, such as unusual muscle pain, trouble breathing, feeling very weak or tired, stomach pain with vomiting, or a slow/irregular heartbeat. Always stay well-hydrated while taking these medicines.

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.

Stomach ulcers and bleeding

Naproxen can cause serious stomach ulcers and internal bleeding. This risk is higher if you have had ulcers before, are over 65, or take other blood-thinning medicines. Stop taking it and see a doctor immediately if you have black, tarry stools or vomit blood.

Asthma

Do not take naproxen if you have ever had an asthma attack, wheezing, or a skin rash triggered by aspirin or other non-steroidal anti-inflammatory drugs (NSAIDs). It can cause a life-threatening allergic reaction or severe breathing difficulties.

Pregnancy (third trimester)

Do not take naproxen if you are more than 20 weeks pregnant. It can cause serious heart or kidney problems in the unborn baby and lead to complications during delivery.

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 naproxen. Both alcohol and naproxen can irritate the lining of your stomach; combining them significantly increases your risk of developing stomach ulcers or internal bleeding.

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

Both metformin and naproxen 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.