Is Magnesium Safe with Vitamin D3?
Free · No account · based on published sources including NIH ODS, FDA drug labels, and peer-reviewed literature
Ensure adequate magnesium intake (310-420 mg/day from diet and supplements) when taking Vitamin D3. Magnesium deficiency can render Vitamin D3 supplementation ineffective. Have magnesium levels checked if Vitamin D3 supplementation is not raising 25-OH-D levels as expected.
Why this interaction occurs
Magnesium is a required cofactor for multiple enzymatic steps in Vitamin D metabolism, including hepatic 25-hydroxylation and renal 1-alpha-hydroxylation to form active 1,25-dihydroxyvitamin D (calcitriol). Magnesium deficiency can cause Vitamin D resistance, making supplementation ineffective. Conversely, high-dose Vitamin D3 can deplete magnesium stores.
Evidence
Evidence level: strong.
Reported safety data
The FDA’s adverse event reporting system (FAERS) has received 708,274 reports mentioning Vitamin D3. This reflects reported cases involving the medication in general — not confirmed causation, and not specific to the Vitamin D3 + 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 interactions → · All Vitamin D3 interactions →
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Educational only — not medical advice.
Always confirm with your doctor or pharmacist.