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Magnesium

Also known as: Magnesium glycinate, Magnesium citrate, Magnesium oxide

An essential mineral involved in hundreds of enzyme reactions, including muscle and nerve function. Many people eat less than recommended.

Common forms: Glycinate · Citrate · Oxide · Malate · Threonate

Draft summary, not yet reviewed by a qualified health professional · Last updated 2026-11-03

Talk to a healthcare professional first

This information is for education only and is not medical advice, diagnosis, or treatment. Supplements can interact with medications and health conditions. Check with your doctor or pharmacist before starting anything, especially if you take medication, are pregnant or breastfeeding, or have a health condition. These statements have not been evaluated by the FDA; supplements are not intended to diagnose, treat, cure, or prevent any disease.

What the evidence says

Heart health markers

BModerate evidence

Meta-analyses of placebo-controlled trials found magnesium lowered blood pressure by about 2–3 mmHg systolic and 2 mmHg diastolic, with larger effects in people with high blood pressure or low magnesium levels.

Dose used in studies
300–400 mg/day elemental magnesium
Time to effect
~1–3 months
Most relevant for
People with high blood pressure or low magnesium levels
Studies (2)

Regularity

BModerate evidence

Magnesium oxide acts as a gentle osmotic laxative; in a meta-analysis of supplement trials, 68% of people with chronic constipation responded to it versus 19% on placebo.

Dose used in studies
500–1,500 mg/day magnesium oxide (split doses)
Time to effect
1–3 days
Studies (1)

Sleep quality

CLimited evidence

Small trials in older adults suggest magnesium may slightly shorten the time to fall asleep, but a 2026 systematic review rated the evidence low to very low certainty and found results inconsistent.

Dose used in studies
250–500 mg/day elemental magnesium in the evening
Time to effect
2–8 weeks
Most relevant for
Older adults with low dietary intake
Studies (2)

Safety

Common side effects

  • Diarrhea (especially oxide and citrate)
  • Stomach upset
  • Nausea

Avoid or ask your doctor first if

  • You have kidney disease (magnesium can build up)

Pregnancy & breastfeeding

Likely safe at normal dietary doses — confirm with your provider.

Upper limit

350 mg/day from supplements (adults), unless directed by a clinician

Medication interactions

  • moderateCertain antibiotics: Binds these antibiotics and reduces absorption — separate by at least 2–4 hours.
  • minorBlood pressure medications: May add to the blood-pressure-lowering effect.

This list covers common medication classes only and is not exhaustive.

Buying tips

Look for third-party testing seals (USP Verified, NSF Certified, or Informed Choice) and match the form and dose used in studies.

Where to buy (affiliate)

Further reading