PlainPill

Magnesium Oxide

People mainly take Magnesium Oxide for sleep, digestion, energy. Based on 90 first-hand reports and 24 meta-analyses & systematic reviews in the medical literature. Ranked #194 of 1,974 overall.

43
User score
Mostly negative
12% positive22% mixed49% negative17% unclear

Of reports that state an outcome, 14% are positive.

Clinical research
AStrong research base
24
meta-analyses
81
RCTs
2,214
papers

What Magnesium Oxide does, according to users

Of the people who reported each effect, the share who said it got better.

What the research says

Systematic reviews and meta-analyses from PubMed, with their published conclusions.

AStrong research base

3+ meta-analyses or systematic reviews and 10+ randomized controlled trials in humans. The grade measures how much human research exists — read the conclusions below for what it found.

Planta Med · 2013 · Meta-analysis / systematic review
Vitex agnus-castus extracts for female reproductive disorders: a systematic review of clinical trials

Conclusion: Limitations include small sample sizes in some studies, heterogeneity of conditions being treated, and a range of reference treatments.Despite some methodological limitations, the results from randomised, controlled trials to date suggest benefits for Vitex extracts in the treatment of premenstrual syndrome, premenstrual dysphoric disorder and latent hyperprolactinaemia. Further research is recommended, and greater transparency in reporting for future trials.

PubMed 23136064 ↗
Cancer Treat Rev · 2024 · Meta-analysis / systematic review
Pharmacological prevention and treatment of opioid-induced constipation in cancer patients: A systematic review and meta-analysis

Conclusion: Magnesium oxide and naldemedine are most likely effective for prevention of OIC in cancer patients. Naloxone in a fixed combination with oxycodone, naldemedine and methylnaltrexone effectively treat OIC in cancer patients with acceptable adverse events. However, their effect has not been compared to standard (osmotic and stimulant) laxatives. More studies comparing standard laxatives with each other and with opioid antagonists are necessary before recommendations for clinical practice can be made.

PubMed 38452708 ↗
Lancet Child Adolesc Health · 2025 · Meta-analysis / systematic review
Efficacy and safety of pharmacological therapies for functional constipation in children: a systematic review and meta-analysis

Conclusion: Polyethylene glycol is probably more effective than placebo and key comparator therapies and should be considered the standard of first-line care. Future studies should consider polyethylene glycol as an index therapy, and clearly describe methods, patient characteristics, and previous therapeutics.

PubMed 41101321 ↗

Dosage people report

As stated by users — not a recommendation. Follow the label or your doctor.

375 mgas reported
1500 mgdaily
dailyas reported
500 mgas reported
800 mgbefore bed
750mgas reported

Reported side effects

How often each side effect came up across all reports.

diarrhea ×15stomach issues ×10laxative effect ×5brain fog ×3stomach pain ×1insomnia ×1increased heart ×1vivid dreams ×1

What users say

Verbatim quotes, shortened only — each links to the original discussion.

“get magnesium citrate or even better, magnesium glycinate, not the oxide though”
Source discussion ↗
“Magnesium oxide doesn't work for sleep, though, because it is poorly absorbed (which is why it works so well as a laxative).”
Source discussion ↗
“Mag oxide usually used to help constipation on its own”
Source discussion ↗
“There are however forms that have been shown to be fairly worthless, mainly magnesium oxide.”
Source discussion ↗
“magnesium oxide supplementation is nearly useless.”
Source discussion ↗
Top discussions (5)

Other options for sleep

User data from public discussions; research from PubMed. Information only, not medical advice — talk to a doctor before starting, stopping or combining anything. Data updated October 2, 2026. How we rate