Can I take Magnesium and Vitamin D together?

Why this happens

This is a 'synergistic' interaction. Magnesium is a necessary 'co-factor' for the enzymes that convert Vitamin D into its active form in the blood. Without enough magnesium, Vitamin D may remain stored and inactive. Conversely, Vitamin D can slightly increase how much magnesium your intestines absorb.

It is usually fine and often recommended to take these together. However, if you have kidney disease or are taking high-dose supplements, you should speak to your doctor or pharmacist first to ensure your dosages are appropriate for your needs.

Hypercalcaemia (high blood calcium)

Do not take vitamin D if you have high levels of calcium in your blood or urine, as it can lead to serious kidney damage and heart rhythm problems.

Kidney disease

If you have severe kidney problems, your body may not be able to remove excess magnesium, leading to dangerously high levels in the blood. Check with your doctor before use.

Alcohol

It is best to avoid or strictly limit alcohol when taking magnesium. Alcohol acts as a diuretic, which can increase the amount of magnesium your body loses through urine, potentially making the supplement less effective. Additionally, chronic alcohol use can lead to magnesium deficiency.

Dairy products (Milk, Cheese, Yoghurt)

Avoid taking magnesium supplements at the same time as large amounts of dairy products. Dairy is high in calcium, and high doses of calcium can compete with magnesium for absorption in the gut, meaning you may not get the full benefit of your supplement. It is best to space them at least 2 hours apart.

Caffeine (Coffee, Tea, Energy drinks)

It is best to limit caffeine intake around the time you take magnesium. Like alcohol, caffeine has a mild diuretic effect and can increase the excretion of magnesium through the kidneys.

High-fat meals

Vitamin D is a fat-soluble vitamin. It is best absorbed by your body when taken with a meal that contains some fat (such as eggs, avocado, nuts, or dairy).

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.