Can I take Losartan and Metformin together?

Why this happens

Losartan can improve how your body responds to insulin, which may enhance the blood-sugar-lowering effect of metformin. Both medications are also processed or cleared through the kidneys, and their combined effect can occasionally put extra strain on kidney function.

What you should do

You can take these medicines together, but you should monitor your blood sugar levels more closely when starting or changing doses. Be sure to stay well-hydrated. If you feel dizzy, shaky, or unusually tired, check your blood sugar. Attend your regular blood tests to monitor your kidney function as requested by your doctor.

Important precautions

Pregnancy

You must not take losartan if you are pregnant. It can cause serious harm or death to an unborn baby, especially if taken during the second and third trimesters.

Severe infection, dehydration, or excessive alcohol intake

In rare cases, metformin can cause lactic acidosis, a serious build-up of acid in the blood. Seek urgent medical help if you experience unexplained muscle cramps, severe tiredness, or breathing difficulties.

X-ray or scan using iodine contrast dye

You must stop taking metformin before and for 48 hours after having an X-ray or scan involving an injection of contrast dye, as this can lead to kidney problems.

Food and drink warnings

Alcohol

It is best to avoid or strictly limit alcohol while taking losartan. Alcohol can increase the blood pressure-lowering effect of losartan, which may make you feel dizzy, lightheaded, or faint, especially when standing up. Combining alcohol with medication also increases the risk of liver damage.

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).

Potassium-rich foods (e.g., bananas, spinach, salt substitutes)

Losartan can increase the levels of potassium in your blood. You should avoid using salt substitutes containing potassium (such as Lo-Salt) and speak to your doctor before significantly increasing your intake of potassium-rich foods, as high potassium levels can affect your heart rhythm.

Vitamin B12 absorption

Long-term use of metformin can interfere with the absorption of Vitamin B12 from your food. Your doctor may monitor your levels or suggest a supplement if you feel unusually tired or have a sore, red tongue.

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.