Magnesium oxide Dosage and Timing: What Owners Report
In 32 Reddit owner comments that give an amount, the typical Magnesium oxide dose was 400 mg (middle half: 267.5 to 500 mg). The timing people mention most is at night or before bed (53 comments). These numbers describe what people with IBS say they take on Reddit (November 2025 to October 2026); they are not dosing advice. Follow the label and ask a doctor or pharmacist, especially if you take medicines.
Amounts owners mention
| Unit | Comments | Typical (median) | Middle half | Most-mentioned amounts |
|---|---|---|---|---|
| mg | 32 | 400 | 267.5 to 500 | 400 (10), 1000 (6), 250 (5) |
| capsules or tablets | 8 | 2 | 1.25 to 3.75 | 2 (3), 4 (2), 1 (2) |
Counted from amounts written next to the name Magnesium oxide in 42 owner comments (a comment can give more than one amount). Products differ in strength, so a number of capsules or scoops is not comparable between brands. Most-mentioned: 400 mg (10), 1000 mg (6), 250 mg (5).
What studies and NIH sources say
- The NIH upper limit for supplemental magnesium is 350 mg a day for adults unless a doctor advises more; people with kidney disease are at higher risk of magnesium build-up.[NIH Office of Dietary Supplements]
- Magnesium can interfere with some antibiotics and bisphosphonates; space doses apart.[NIH Office of Dietary Supplements]
When people take it
| Timing mentioned | Owner comments |
|---|---|
| At night or before bed | 53 |
| In the morning | 16 |
| On an empty stomach | 7 |
| With or after food | 4 |
Phrases such as "before bed", "in the morning" or "with food" near the name Magnesium oxide.
In their words
4/5“Now at 32 I have not had an attack like this in almost a year whilst taking 400mg of magnesium oxide every night before bed..”
4/5“Magnesium oxide at bedtime helped me tremendously.”
1/5 Pain & crampingRegularity“I take a daily magnesium oxide supplement every night before bed.”
4/5“I’ve been using 400 mg of magnesium oxide daily for years(4 years or so).”
4/5 Fast-acting“I'm taking magnesium oxide before bed and that's helping me go the next day.”
5/5“I take 400mg magnesium oxide daily and works wonders!”
Magnesium oxide overall: 4.0 from 279 owner comments.
Frequently asked
How much Magnesium oxide do people take?
In 32 Reddit owner comments that give an amount, the typical Magnesium oxide dose was 400 mg (middle half: 267.5 to 500 mg). That is what people report, not a recommended dose; follow the product label and your doctor's advice.
When do people take Magnesium oxide?
The timing people mention most is at night or before bed (53 comments). In the morning: 16; On an empty stomach: 7.