- Magnesium citrate, best-studied, good bioavailability, may cause loose stools
- Magnesium glycinate/bisglycinate, excellent absorption, least GI side effects, best for sleep
- Magnesium chloride, good bioavailability, less GI upset
- Magnesium threonate, marketed for brain health (limited evidence, expensive)
- AVOID: Magnesium oxide, extremely poor absorption, mostly acts as a laxative
- AVOID: Magnesium carbonate, poor absorption, high GI side effects
Reduces drug absorption
Separate by 2+ hours before or 4-6 hours after.
Reduces drug absorption
Separate by 2+ hours before or 4-6 hours after.
Metabolic alkalosis risk
Avoid combination in kidney disease.
Depletes magnesium
Monitor Mg levels with long-term PPI use. Consider H2 blockers instead.
Neuromuscular blockade risk (IV only)
Relevant mainly for IV magnesium. Oral supplementation is generally safe.
Enhanced paralysis (IV only)
Inform anesthesiologist of magnesium use before surgery.
Reduces drug absorption
Separate dosing times.
Neuromuscular weakness
Monitor in neonatal settings.
Reduces drug absorption
Separate by 2+ hours.
Reduces drug absorption
Separate by 2+ hours.
Reduces drug absorption
Separate by 2+ hours.
Reduces drug absorption
Separate by 2+ hours.
Reduces absorption (both ways)
Take at separate times.
Reduces drug absorption
Separate by 2+ hours.
Reduces drug absorption
Take levothyroxine on empty stomach, magnesium 4+ hours later.
Synergistic effects
Medical supervision required.
Additive glucose reduction
Monitor blood glucose. Effect is likely small.
Additive BP reduction
Monitor BP. Beneficial in most cases.
Increases absorption rate
Monitor for hypoglycemia.
Reduces drug absorption
Separate by 2+ hours.
Possible reduced clotting
Use caution with bleeding disorders.
Increases magnesium levels
Monitor if supplementing.
Oral (relevant to supplements):
Intravenous/Intramuscular (medical settings only):
△ KEY RULE: Take magnesium at least 2 hours BEFORE or 4-6 hours AFTER these medications to reduce interaction risk.
These medications can lower your magnesium levels, supplementation may be needed:
Nearly 60% of tested magnesium supplements (Poland study) had amounts differing from the label, ranging from 304% more to 98% less than stated. Some contained trace lead and uranium (unclear if dangerous). One German manufacturer's products were contaminated with anabolic steroids. Avelor strongly recommends third-party tested products.
Not Prohibited. Not on the 2026 WADA list. However, cross-contamination risk exists (anabolic steroid contamination documented in 2005). Athletes should use NSF Certified for Sport or Informed Sport products.
Nearly 60% of tested magnesium supplements (Poland study) had amounts differing from the label, ranging from 304% more to 98% less than stated. Some contained trace lead and uranium (unclear if dangerous). One German manufacturer's products were contaminated with anabolic steroids. Avelor strongly recommends third-party tested products.
Reference identifiers on this page are being re-verified against PubMed. Some may not yet link to the paper named beside them.
**, Zhang X et al. "Effects of magnesium supplementation on blood pressure: A meta-analysis." *Hypertension*, 2016. Key finding: Meta-analysis of 34 RCTs (2,028 participants) found magnesium supplementation significantly reduced systolic and diastolic blood pressure.
Effects of magnesium supplementation on blood pressure: A meta-analysis.. (2016). PMID: 27402922
**, Veronese N et al. "Effect of magnesium supplementation on glucose metabolism in people with or at risk of diabetes." *Eur J Clin Nutr*, 2016. Key finding: Magnesium supplementation significantly improved fasting glucose and HOMA-IR in people with diabetes.
Effect of magnesium supplementation on glucose metabolism in people with or at risk of diabetes.. (2016). PMID: 27530471
**, Mah J et al. "Oral magnesium supplementation for insomnia in older adults: a Systematic Review & Meta-Analysis." *BMC Complement Med Ther*, 2022. Key finding: Magnesium supplementation improved subjective measures of insomnia, particularly sleep onset latency.
Oral magnesium supplementation for insomnia in older adults: a Systematic Review & Meta-Analysis.. (2022). PMID: 35184264
Based on independent third-party laboratory analysis
Category pass rate: ~80% of magnesium products passed independent laboratory testing. However, form accuracy is a MAJOR issue — some brands label one form but contain a different (cheaper) form.
Contamination risk: Low risk category. Heavy metals rarely an issue in mineral supplements at tested doses.
Independently graded against 173,636 indexed supplements with 177 published clinical interactions, sourced from PubMed, FDA CAERS, openFDA, and NIH DSLD | Last updated: April 5, 2026
Not medical advice. Based on published clinical research and systematic reviews.
Magnesium · interaction landscape
9 flagged
0
Dangerous
6
Moderate
3
Timing
0
Pre-op
Safety
Moderate interactions. Monitoring, timing separation, or dose adjustment may be required.
Levothyroxine (Synthroid)
SourceFDA label
Fluoroquinolone antibiotics (Cipro, Levaquin)
SourceFDA label
Tetracycline antibiotics
SourceFDA label
Bisphosphonates (Fosamax, Boniva)
SourceFDA label
Muscle relaxants and sedatives
SourceClinical consensus
Potassium-sparing diuretics
SourceClinical pharmacology
Timing Separation Rules
Educational information only. This is not medical advice. These statements have not been evaluated by the FDA. Talk to your prescriber before starting, stopping, or combining any supplement with prescription medication.