Can You Take Vitamin C With Magnesium?

Quick answer

No official source we read names a clash between vitamin C and magnesium. What they share is a side effect: at high doses, the part of each that is not absorbed draws water into the gut. Their limits count differently: 2,000 mg of vitamin C from all sources, 350 mg of magnesium from supplements only.^1,2,3

Key facts

Food counts toward the vitamin C limit of 2,000 mg a day, but not toward magnesium's 350 mg, which covers supplements and medicines.^3,4
For both nutrients, smaller amounts are absorbed more completely: a single 200 mg dose of vitamin C was fully absorbed, and magnesium uptake is higher from several small amounts than from one large one.^5,6
NIH's magnesium fact sheet does not mention vitamin C, and its vitamin C sheet does not mention magnesium.^1,2
Each carries a kidney caution for its own reason: vitamin C raises oxalate in urine, and magnesium builds up when the kidneys cannot clear it.^1,2

What the sources say about the pair

Neither NIH fact sheet mentions the other nutrient, and we found no trial that tested the two as a pair. The trials that included both mixed them into multivitamins with many other ingredients. So nothing documents a clash, and nothing shows that the pair does more than each does alone.^1,2

They are also very different substances. Vitamin C is a water-soluble vitamin that people cannot make, so it has to come from food or supplements. Magnesium is a mineral the body stores: an adult holds about 25 g, half or more of it in bone.^1,2

Where their roles meet

Their best-established roles meet in bone. Vitamin C is needed to make collagen, the protein framework of bone, while magnesium is part of the mineral structure itself. These are separate roles of each nutrient, and we found no trial of the pair for bone.^1,2

Contributes to normal collagen formation for the normal function of skin, gums, teeth, bones, cartilage and blood vessels*^1,7,8

Moderate evidence

A well-established nutrient function. NIH states that vitamin C is required to make collagen, an essential part of connective tissue, and EU regulators permit this wording, as six separate statements, for foods that are at least a source of vitamin C. Normal skin holds high levels of vitamin C. The claim describes what the body needs vitamin C for. It does not show that extra vitamin C changes how skin looks in someone who already gets enough, and how creams and serums compare with getting enough in the diet is poorly understood.

Amount studied: Recommended intake: 75 mg a day for women and 90 mg for men, from food and supplements

Contributes to the normal structure of bone*^2,3

Moderate evidence

A long-established role of the mineral, described by NIH: half or more of the body's magnesium is held in bone, where it is part of the bone's structure and takes part in bone formation. This is a role of the nutrient. NIH describes the trials of whether extra magnesium changes bone density as few and small, and says more research is needed.

Amount studied: Recommended daily intake from food and supplements

How each one is absorbed

About 70% to 90% of vitamin C is absorbed at intakes of 30 to 180 mg a day. Above 1 g a day, less than half is absorbed, and the absorbed excess is passed in urine.¹

The share of magnesium the gut absorbs is higher when it is taken in several small amounts through the day than in one large amount.⁶

Forms of magnesium that dissolve well in liquid, such as citrate, chloride, lactate and aspartate, are absorbed more completely than magnesium oxide.²

For both, one big dose is the least efficient way to take them. Absorbed vitamin C beyond what the body needs leaves in urine, and magnesium that is not absorbed stays in the gut, which is where the shared side effect below comes from.^1,2

How much room each limit leaves

Daily amounts for adults, from NIH, and what our products give^1,3
	Vitamin C	Magnesium
Recommended amount	75 mg for women, 90 mg for men	310 to 320 mg for women, 400 to 420 mg for men
Upper limit	2,000 mg	350 mg
What counts toward it	Food, drinks and supplements	Supplements and medicines only
Our Men's Multi	150 mg, as ascorbic acid	50 mg, as magnesium oxide
Our other products	Immune formula, 180 mg	Magnesium Glycinate, 275 mg; Creatine + Electrolytes, 60 mg

Vitamin C leaves far more room under its limit. Our immune formula and Men's Multi together give 330 mg of vitamin C, a sixth of the limit, while Magnesium Glycinate and Men's Multi together give 325 mg of magnesium, 25 mg short of it.^1,3

What's in ours

What’s in ours

Men's Multi: Vitamin C, 150 mg per serving, from the label
Immune Support: Vitamin C, 180 mg per serving, from the label

What’s in ours

Magnesium Glycinate: Magnesium, 275 mg per serving, from the label
Men's Multi: Magnesium, 50 mg per serving, from the label
Creatine + Electrolytes: Magnesium, 60 mg per serving, from the label

Our Magnesium Glycinate with our Men's Multi

Magnesium Glycinate and Men's Multi together provide 325 mg of magnesium a day, close to the 350 mg upper limit for magnesium from supplements. Do not add another magnesium product.

The side effect they share

This is the one thing the two have in common. With vitamin C, high doses can bring diarrhea, nausea and cramps because the vitamin C that is not absorbed pulls water into the gut.¹

The laxative effect comes from unabsorbed magnesium salts drawing water into the intestine and colon, and from faster movement of the gut.²

The forms most often reported to cause diarrhea are magnesium carbonate, chloride, gluconate and oxide.²

We found no study of the two taken together, so whether the effects add up has not been measured. Keeping each one within its own limit is the only guide the sources give.^1,2

Medicines and who should ask first

High vitamin C intakes raise oxalate and uric acid in urine. NIH says that could add to kidney stones, with the best evidence in people who already pass too much oxalate.¹

The risk of magnesium toxicity rises when the kidneys work poorly or have failed, because they cannot remove the excess.²

Ask your pharmacist or doctor first

Vitamin C taken at the same time as levothyroxine might increase how much of the medicine is absorbed.⁹

Reported in studies

Ask your pharmacist how far apart to take them

The levothyroxine label lists antacids, such as those made with aluminum and magnesium hydroxides, among products that may reduce levothyroxine absorption by lowering stomach acid. In a small 2025 study, magnesium aspartate taken at the same time lowered levothyroxine absorption by 12%, and magnesium citrate by 7%, a drop too small to rule out chance.^10,11,12

On the medicine's label

Note the opposite directions. Vitamin C might raise how much levothyroxine is absorbed, while antacids containing magnesium may lower it. If you take levothyroxine, ask your pharmacist how to fit both around your dose.^9,10

Ask your doctor first if you have had kidney stones or have kidney disease^1,2
Ask first if you have hemochromatosis or another cause of iron overload¹
Ask first if you take a statin, an amphetamine medicine, an antibiotic, a bisphosphonate, a diuretic, a medicine for acid reflux or gabapentin^3,4
Ask first if you are having chemotherapy or radiation therapy¹
Ask first if you are pregnant or nursing

Questions people ask

Can you take vitamin C with magnesium glycinate?

No source names a problem with that form. In a four-week trial, 250 mg of magnesium a day as bisglycinate caused no more side effects than placebo, and NIH describes vitamin C as low in toxicity, with gut upset the usual complaint at high intakes.^1,13

Should you take them at different times of day?

No source we read calls for it, and neither NIH fact sheet gives a time of day for either nutrient. What the absorption studies do show is that, for both, splitting a large amount into smaller ones means more of it is absorbed.^4,5,6

See what we make

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See the Full Measure line Creatine + Electrolytes Magnesium Glycinate Men's Multi

Sources

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

This page is information, not medical advice. Talk to your doctor or pharmacist about your own situation.