Magnesium Toxicity: Supplemental UL 350 mg/day (Heart Risk)

Supplemental magnesium above 350 mg/day can cause diarrhea and irregular heartbeat. People with kidney problems are at higher risk. Check your safe dose.

Magnesium Overdose Risk

Excess magnesium often causes diarrhea; very high doses can affect heart rhythm in susceptible people.

Safe Dosage Upper Limits (5 Regional Standards)

StandardRDAUpper Limit (UL)
US (FDA)420 mg350 mg
EU (EFSA)420 mg350 mg
AU (TGA)420 mg350 mg
CN (CNS)330 mg350 mg
JP (MHLW)340 mg350 mg

RDA = Recommended Dietary Allowance. UL = Tolerable Upper Intake Level. Exceeding the UL long-term may cause the toxicity symptoms described above.

Frequently Asked Questions

Can magnesium supplements be dangerous?

At normal doses (200-400 mg/day), magnesium is very safe. Excess typically causes diarrhea. However, very high doses (especially in people with kidney problems) can cause dangerously low blood pressure, irregular heartbeat, and cardiac arrest. The UL for supplemental magnesium is 350 mg/day.

Check if Your Magnesium Intake Is Safe

Scan your supplement labels with NutriAudit. Automatically calculate total intake from all sources and detect if you exceed safe limits.

Reviewed by NutriAudit editorial team. Based on public reference data from NIH ODS, FDA, EFSA, and other cited sources. Not medical advice.

Not medical advice. Always consult a qualified healthcare professional for personal medical decisions.