Can I take Losartan and Magnesium together?

Why this happens

Both losartan and magnesium can lower blood pressure. When used together, their effects can add up, potentially making your blood pressure drop lower than intended. Furthermore, losartan causes the body to hold onto potassium; while magnesium is generally safe, some magnesium formulations or kidney issues can lead to an imbalance of salts (electrolytes) in the blood.

What you should do

You can usually take these together, but you should monitor your blood pressure regularly. If you feel dizzy, lightheaded, or faint—especially when standing up—speak to your doctor. It is best to space the doses out by at least 2 hours if you are taking a high-dose magnesium supplement to ensure it doesn't interfere with how the medicine is absorbed. Always inform your doctor if you are taking magnesium, as they may want to check your kidney function and potassium levels.

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.

Kidney disease

If you have kidney problems, you must be closely monitored while taking these. Magnesium can build up to toxic levels, and losartan can further affect kidney function.

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.

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.

Dairy products and high-calcium foods

Large amounts of calcium from dairy products or supplements can interfere with the absorption of magnesium if taken at the exact same time. It is best to space these out by at least 2 hours.

High-fibre foods and Phytic acid (e.g. whole grains, legumes)

Foods very high in fibre or phytic acid can bind to magnesium in the gut and reduce the amount your body absorbs. If you are taking magnesium to treat a deficiency, try to take it at a different time from very high-fibre meals.

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.