Excess magnesium from supplements commonly causes diarrhea. Very high doses can affect heart rhythm. Learn the safe upper limits and who is most at risk.
Excess magnesium often causes diarrhea; very high doses can affect heart rhythm in susceptible people.
| Standard | RDA | Upper Limit (UL) |
|---|---|---|
| US (FDA) | 420 mg | 350 mg |
| EU (EFSA) | 420 mg | 350 mg |
| AU (TGA) | 420 mg | 350 mg |
| CN (CNS) | 330 mg | 350 mg |
| JP (MHLW) | 340 mg | 350 mg |
RDA = Recommended Dietary Allowance. UL = Tolerable Upper Intake Level. Exceeding the UL long-term may cause the toxicity symptoms described above.
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.
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Not medical advice. Always consult a qualified healthcare professional for personal medical decisions.