Combination check · NIH reference values

Can you take Iron and Magnesium together?

Space them out

Yes, you can take both in the same day — but Iron and Magnesium compete for absorption at supplemental doses, so take them at least 2 hours apart.

🕑 How to time them

Separate the doses by about 2 hours, or take them with different meals. The competition matters most at higher doses on an empty stomach.

Iron and Magnesium are both minerals that use overlapping absorption pathways in the gut. Neither is dangerous alongside the other — the issue is efficiency: taken in the same sitting at supplemental doses, you absorb less of each.

For context: a typical daily amount of Iron is 8–18 mg, and the upper limit for Iron is 45 mg. A typical daily amount of Magnesium is 310–420 mg, and the upper limit for Magnesium is 350 mg*.

The two supplements, side by side

Mineral

🩸 Iron

Oxygen transport, energy, prevents anemia.

Typical / RDA8–18 mg
Upper limit45 mg
EvidenceStrong
Full Iron guide →
Mineral

🌙 Magnesium

Muscle & nerve function, sleep, 300+ reactions.

Typical / RDA310–420 mg
Upper limit350 mg*
EvidenceModerate
Full Magnesium guide →

What each one needs you to watch

  • Iron:Do not supplement without reason — excess accumulates and damages organs.
  • Iron:Coffee, tea, calcium, and zinc reduce absorption — separate them.
  • Iron:Vitamin C boosts uptake of plant (non-heme) iron.
  • Magnesium:Cofactor that helps activate vitamin D.
  • Magnesium:Space 2 h from high-dose zinc.
  • Magnesium:Can reduce absorption of some antibiotics & bisphosphonates.

Common questions

Can you take Iron and Magnesium together?

Yes, you can take both in the same day — but Iron and Magnesium compete for absorption at supplemental doses, so take them at least 2 hours apart.

How should you time Iron and Magnesium?

Separate the doses by about 2 hours, or take them with different meals. The competition matters most at higher doses on an empty stomach.

Are Iron and Magnesium already in a multivitamin?

Usually yes — most multivitamins contain both Iron and Magnesium. If you take a multi on top of standalone pills, add up all three labels; the combined total is what counts against each nutrient's upper limit.

Related guides

Check other combinations

Iron + Vitamin D3Iron + ZincIron + CalciumIron + Vitamin CMagnesium + Vitamin D3Magnesium + ZincMagnesium + CalciumMagnesium + Vitamin CAll combinations →

Sources

Reference values: NIH Office of Dietary Supplements, adult general population. Educational information only — not medical advice. Medication interactions are individual: confirm your specific situation with a healthcare professional.

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