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Magnesium Oxide Absorption: Why the Form on the Label Matters
Magnesium oxide absorption is modest: the body takes in less of it than of forms that dissolve well in water, and the unabsorbed part stays in the gut, where it can loosen stools. Reviralis prints magnesium oxide 50 mg per two capsules, 12% of the Daily Value, far under the 350 mg supplement limit.
Written by the Goreviralis label deskUpdated · 4 min read
Why is magnesium oxide absorption lower than other forms?
Oxide holds a lot of magnesium by weight but dissolves poorly, so less of it crosses the gut wall.
Picture a chalky tablet that mostly stays chalky. NIH notes that forms which dissolve well in liquid, such as citrate and chloride, are absorbed more completely than oxide (NIH ODS, Magnesium). The leftover magnesium draws water into the bowel. That is why oxide is also sold as a laxative.
The Reviralis label prints "Magnesium (as Magnesium Oxide) 50 mg". It does not say how much of that reaches your blood, and no source measured it for this product.
How much magnesium is 50 mg next to a day's need?
It is about an eighth of a day's need and one seventh of the supplement limit.
Adults need 310 to 320 mg (women) or 400 to 420 mg (men) from food and supplements. The upper limit of 350 mg applies to magnesium from supplements only, not to food (NIH ODS, Magnesium). Fifty mg is 14% of that limit, so a single capsule serving leaves room.
| Measure | Amount | Share the label line fills |
|---|---|---|
| Label line (2 capsules) | 50 mg, 12% DV | Printed |
| Adult need, women | 310 to 320 mg | About 16% |
| Adult need, men | 400 to 420 mg | About 12% |
| Upper limit, supplements | 350 mg | About 14% |
Can magnesium oxide upset the stomach?
Yes, in larger doses; diarrhea is the usual sign.
NIH ties loose stools and cramps to supplemental magnesium above the 350 mg limit (NIH ODS, Magnesium). At 50 mg that is unlikely on its own. The risk is stacking: an antacid, a laxative and a multivitamin can each carry magnesium.
- Read the Supplement Facts on every product you take.
- Add the magnesium lines in mg.
- If you pass loose stools, tell your pharmacist which products you use.
See the side effects page for the full label caution.
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See packsWhich medicines need a gap from magnesium?
Some antibiotics, thyroid hormone and bone-drug tablets absorb less when magnesium is in the gut at the same time.
The label asks you to check with your healthcare provider before use if you take prescription medicine. Keep taking any prescribed medicine, including an antiviral, and ask before changing the timing.
- Some antibiotics, including quinolone and tetracycline types
- Thyroid hormone tablets
- Bone-drug tablets
More detail sits on the medicine check page and in the antibiotics and minerals post.
What should I ask my pharmacist about magnesium?
Bring the bottle and ask three short questions.
1. Which of my medicines should be two or more hours from a magnesium product? 2. Is my total magnesium from supplements under 350 mg? 3. Is oxide a poor fit for my stomach?
No source tests Reviralis Complete itself, so the label is your best guide. The other amounts are on the Supplement Facts page and in the major minerals group.
FAQ01
Reviralis questions people ask
Is magnesium oxide poorly absorbed?
Yes, compared with citrate or chloride. NIH notes that forms which dissolve well in liquid are absorbed more completely than oxide. The part that is not absorbed stays in the gut and can pull in water, which is why oxide is also used as a laxative.
How much magnesium oxide is in Reviralis?
The label prints magnesium as magnesium oxide, 50 mg per two capsules, or 12% of the Daily Value. The label does not say how much is absorbed. One bottle holds 30 servings.
Is 50 mg of magnesium too much?
No. The adult upper limit for magnesium from supplements is 350 mg, so 50 mg is about 14% of it. Add up every supplement and antacid you use, because the limit applies to the total.
Does magnesium oxide cause diarrhea?
It can at larger doses. NIH links loose stools and cramps to supplemental magnesium above 350 mg a day. At 50 mg the effect is unlikely alone, but several magnesium products together can pass that line.
Should I take magnesium with thyroid medicine?
Ask your pharmacist first. NIH lists thyroid hormone among medicines that magnesium can affect when taken at the same time. A gap of a few hours is a common answer, but your pharmacist knows your prescription.
Who wrote this02
Written and reviewed by
Pages built from the label, the sales page and linked NIH, CDC, FDA, FTC, Mayo Clinic and peer-reviewed sources.
Last updated . Read our editorial standards and how we check reviews. This website is the information site for a U.S. stocking partner for Reviralis. It is not the manufacturer or the distributor named on the label. We earn money when you buy through our order links.
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