Is Magnesium supplement Safe with Calcium supplement?
Free · No account · based on published sources including NIH ODS, FDA drug labels, and peer-reviewed literature
At standard supplemental doses (calcium ≤500 mg, magnesium ≤350 mg), this interaction is clinically minor. However, avoid taking very high-dose calcium (>1000 mg) simultaneously with magnesium. Spacing by 1 hour is a reasonable precaution for patients on therapeutic doses of both.
Why this interaction occurs
Calcium and magnesium share intestinal absorptive pathways. At very high calcium intake, competitive inhibition of magnesium absorption has been demonstrated. At typical supplemental doses the effect is minimal, but patients requiring both minerals for medical conditions (e.g., osteoporosis with hypomagnesemia) should consider separation.
Evidence
Evidence level: limited.
Reported safety data
The FDA’s adverse event reporting system (FAERS) has received 620,762 reports mentioning Calcium supplement. This reflects reported cases involving the medication in general — not confirmed causation, and not specific to the Calcium supplement + supplement combination on this page.
FAERS reports are voluntary and cannot prove that a drug caused an event. Do not use report counts to assess the safety of this specific drug-supplement pair.
Frequently asked questions
Related interactions
All Magnesium supplement interactions → · All Calcium supplement interactions →
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Educational only — not medical advice.
Always confirm with your doctor or pharmacist.