Stool form and regularity
NBPure MagO7 Ozonated Magnesium Oxide
A magnesium oxide capsule taken at bedtime, in a trademarked ozonated form, for occasional constipation and bloating.
- Format
- Capsule, once a day
- Type
- Magnesium
- Cost
- $0.93 a day
- Customer rating
- 4.6 out of 5 from 48,174 ratings from Amazon
What customers consistently report
- Working overnight without cramping for many people
- A gentler effect than stimulant laxatives
- A bedtime routine that suits travel or medication-related constipation
Those are the themes that recur across the reviews. Moderate review confidence — Amazon shows 4.6 from more than 48,000 ratings as an independent figure and the brand widget a similar 4.8 from 6,744, but no Trustpilot profile exists, and the 52,000 five-star reviews the brand advertises combine platforms.
Why it might work
Magnesium oxide is poorly absorbed, and the magnesium left in the intestine holds water there, which softens stool and speeds its passage; this osmotic action is why magnesium salts are used as laxatives. The brand adds that its ozonated oxides carry oxygen that releases over time, and describes potassium as helping fluid balance. The oxygen claim is the part nobody has tested. The printed amount, 1,035 mg of magnesium per serving, is almost three times the 350 mg a day the NIH sets as the upper limit for supplemental magnesium, a limit based on diarrhea, which here is the intended effect. People with kidney problems clear magnesium more slowly, and magnesium can lower the absorption of some antibiotics and osteoporosis drugs.
What the research supports
No trial of MagO7 or of ozonated magnesium oxide was found. Two placebo-controlled trials in Japan of plain magnesium oxide at 1.5 g a day for 28 days found 70.6% against 25.0% overall improvement in 34 women and 68.3% against 11.7% with placebo in 90 adults, and a 2023 pooled analysis of the two gave a relative risk of response of 3.32. The label’s 1,035 mg of elemental magnesium per three capsules is about 1.7 g of magnesium oxide, which sits in the range those trials used, but they gave it in three daily doses and none tested an ozonated form.
What the label discloses
The panel lists magnesium as ozonated magnesium oxides (the trademarked MOXiO3) at 1,035 mg and potassium citrate at 99 mg, with rice flour as the only filler and no proprietary blend. The ozonated, oxygen-standardized claim has no printed oxygen figure and no study behind it. No testing laboratory or certificate was found, and the bottle’s purity-tested mark names nobody.
Who this tends to suit
We match this product to people reporting constipation, irregular bowel habits and bloating. It fits someone whose priority is regularity or resetting after a course of antibiotics or an upset. Whether it is the best fit for you depends on the rest of your answers — what you have already tried, what format you will take, and anything that has to be ruled out.
Where it may not fit
The label supports gluten-free, dairy-free, vegan and no added sweeteners. We flag this product for anyone pregnant or breastfeeding or taking prescription medication, and the quiz removes it rather than recommending it in those cases. That is a caution about who should be deciding, not a claim about the product. A capsule only works if you will take it once a day, every day.
Side effects and what to be aware of
Reviewers who report no effect, cramping or vomiting are a minority; the brand widget has 57 one- and two-star reviews out of 6,744 and Amazon shows 5% one-star. Several mention a formula or capsule-size change, a few mention subscription cancellations that did not stop, and one says to start below the three-capsule label dose. Amazon’s safety text tells people with heart or kidney disease to ask a doctor first, and the serving is far above the NIH upper limit for supplemental magnesium.
Common questions
Does MagO7 work for constipation?
No trial of MagO7 itself was found. Plain magnesium oxide at 1.5 g a day improved symptoms in two placebo-controlled trials in Japan (70.6% against 25.0% in 34 women; 68.3% against 11.7% in 90 adults), and MagO7’s three-capsule serving is about 1.7 g of magnesium oxide by weight. Amazon reviews are 4.6 from about 48,000 ratings, and the brand widget’s 57 one- and two-star reviews are mostly that it did not work for them.
Is MagO7 safe, and what are its side effects?
One serving carries 1,035 mg of magnesium, about three times the 350 mg a day the NIH lists as the upper limit for supplemental magnesium, and the NIH says high doses often cause diarrhea, nausea and cramping. Reviewers report cramping, gas, vomiting or a day spent near the toilet, and Amazon’s safety text says to ask a doctor with a cardiac history or kidney disease. The NIH notes that magnesium toxicity risk rises with impaired kidney function.
How do I take MagO7, and how many capsules?
The label says three capsules at bedtime on an empty stomach with 8 to 12 ounces of water, for 7 to 10 days or until the desired effect, and that you may add up to two capsules or reduce for maintenance. One reviewer who took two capsules still had a strong reaction and suggested starting lower. Magnesium can interfere with the absorption of some antibiotics and osteoporosis medicines, so the NIH advises spacing them by hours.
How much does MagO7 cost?
The 90-capsule bottle is $27.95 one time on the brand site and Amazon, which is $0.93 a day at three capsules, or about $1.55 at five. The brand site’s subscription is 25% off ($20.96 for 90 capsules, $0.70 a day), and shipping is free over $49. The 180-capsule bottle is $41.95, or $0.70 a day.
Can I cancel the MagO7 subscription and get a refund?
The brand offers a refund of the product price within 60 days (shipping not refunded) by email, and says subscriptions can be changed or cancelled through the order confirmation email. A few reviewers on the brand’s widget say a subscription kept shipping after they cancelled, including one who bought on TikTok. No Trustpilot profile exists, so there is no independent complaint record either way.
Before you take this. Speak to a doctor or pharmacist first if you are pregnant or breastfeeding, or taking prescription medication. Nothing on this page is medical advice, and no supplement diagnoses, treats, cures or prevents disease.
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Related reading
Background on how this type of product works, read from the trial evidence.