Can I take magnesium and calcium together?
No official source we checked gives a spacing rule for magnesium and calcium or says one lowers the other's absorption. The NIH says magnesium helps move calcium across cell membranes [1]. For calcium itself, absorption from supplements is highest with doses of 500 mg or less and is generally greater with food [2].
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What the sources say about magnesium and calcium
The NIH says magnesium plays a role in the active transport of calcium and potassium ions across cell membranes [1]. Severe magnesium deficiency can disrupt mineral balance and cause low blood calcium [1][2]. The NIH magnesium and calcium fact sheets do not describe either mineral lowering the other's absorption [1][2]. Vitamin D, not magnesium, is the nutrient the NIH names as required for calcium to be absorbed in the gut by active transport [2].
How to time them
No official source gives a spacing rule for these two. For calcium, absorption from supplements is highest with doses of 500 mg or less, and absorption is generally greater when calcium is taken with food [2]. In people with low stomach acid, calcium carbonate may be absorbed less unless it is taken with a meal [2]. For magnesium, the NIH gives no food rule; the citrate, aspartate, lactate and chloride forms tend to be more bioavailable than oxide and sulfate [1]. Adult upper limits are 350 mg a day of supplemental magnesium [1] and 2,000 to 2,500 mg a day of calcium, depending on age [2].
Who should ask a doctor or pharmacist first
Ask your pharmacist first if you take medicines, because both minerals have spacing rules with some of them. Quinolone antibiotics interact with both [1][2]; magnesium also lowers the absorption of oral bisphosphonates and binds tetracyclines [1]. Levothyroxine should not be taken within 4 hours of calcium carbonate, dolutegravir should be taken 2 hours before or 6 hours after calcium, and lithium plus calcium could raise the risk of high blood calcium [2]. People with impaired kidney function have a higher risk of magnesium toxicity [1].
Supin schedules what you take around each other
Supin puts what you take into a daily routine by time of day, follows each product's label, and reminds you.
Questions people ask next
Sources
- Magnesium: Fact Sheet for Health Professionals — NIH Office of Dietary Supplements
- Calcium: Fact Sheet for Health Professionals — NIH Office of Dietary Supplements
Educational information, not medical advice, and not a recommendation for you. Check with your doctor or pharmacist before starting, combining or changing supplements, especially if you take medication, are pregnant or have a health condition. Supin sells a subscription, not supplements. Last reviewed .