Check before you startThis one has documented interactions with medication classes where the consequences are serious. If you take any prescription medicine, run it past a pharmacist before starting.
How long to take it
Months rather than years for most people. Reassess once sleep, cramps, or stress have settled and food can carry it.
Who it's actually for
People under sustained stress, heavy exercisers, poor sleepers, and those on long-term acid blockers or diuretics.
Safe upper limit
Verified350 mg per day from supplements (no limit from food)
Excess supplemental magnesium causes diarrhoea first. In kidney impairment it can accumulate dangerously.
Applies to supplemental magnesium only, not dietary. A 2023 peer-reviewed paper argues this 1997 figure is outdated (Costello et al., Adv Nutr) — the official number hasn't changed, but the debate is real.
Interactions to know about
- Antibiotics — Especially tetracyclines and quinolones
- Bone medication — Alendronate, risedronate
- Diuretics (water tablets) — Furosemide, bendroflumethiazide, spironolactone
- Reduced kidney function — CKD, dialysis, or a single kidney
Other supplements:
Run your full list through the interaction check.
Practical notes
- Glycinate for sleep and calm, citrate if constipation is part of the picture, malate for daytime.
- Oxide is cheap and poorly absorbed — mostly a laxative.
- Separate from iron, zinc and calcium by two hours.