- 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.
Possible additive BP lowering
Monitor BP with a clinician.
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.
**, 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 178,763 indexed supplements and 757 reviewed supplement and medication pairs, 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.
Safety
Fluoroquinolone antibiotics (Cipro, Levaquin)
Take at different times
Take ciprofloxacin at least 2 hours before or 6 hours after magnesium. Take levofloxacin at least 2 hours before or after magnesium. Take moxifloxacin at least 4 hours before or 8 hours after magnesium. For any other fluoroquinolone or a tetracycline, ask your pharmacist how far apart to take them, because magnesium reduces how much of the antibiotic is absorbed.
Reduced absorption and bioavailability of the antibiotic, potentially leading to decreased systemic exposure and treatment failure against bacterial infections.
Magnesium ions form insoluble chelates with fluoroquinolones and tetracyclines in the gastrointestinal tract. This complexation prevents the antibiotic from being absorbed across the intestinal mucosa.
Tetracycline antibiotics
Take at different times
Take ciprofloxacin at least 2 hours before or 6 hours after magnesium. Take levofloxacin at least 2 hours before or after magnesium. Take moxifloxacin at least 4 hours before or 8 hours after magnesium. For any other fluoroquinolone or a tetracycline, ask your pharmacist how far apart to take them, because magnesium reduces how much of the antibiotic is absorbed.
Reduced absorption and bioavailability of the antibiotic, potentially leading to decreased systemic exposure and treatment failure against bacterial infections.
Magnesium ions form insoluble chelates with fluoroquinolones and tetracyclines in the gastrointestinal tract. This complexation prevents the antibiotic from being absorbed across the intestinal mucosa.
Bisphosphonates (Fosamax, Boniva)
Take at different times
Take alendronate at least 30 minutes before magnesium. Take ibandronate at least 60 minutes before magnesium. For risedronate or any other bisphosphonate, ask your pharmacist how far apart to take them, because magnesium reduces how much of the bisphosphonate is absorbed.
Decreased absorption and bioavailability of bisphosphonates, potentially reducing their efficacy in treating osteoporosis.
Magnesium and other divalent cations physically bind to bisphosphonates in the gastrointestinal tract through chelation. This forms an insoluble complex that prevents the bisphosphonate from being absorbed into the bloodstream.
Levothyroxine (Synthroid)
Muscle relaxants and sedatives
Potassium-sparing diuretics
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.