The U.S. NIH adult UL is 350 mg/day for magnesium from supplements and medications, excluding food magnesium. Review combined label doses and the reference scope.
Excess magnesium often causes diarrhea; very high doses can affect heart rhythm in susceptible people.
| Standard | RDA | Upper Limit (UL) |
|---|---|---|
| United States | 420 mg | 350 mg |
| European Union | 420 mg | 250 mg |
| Australia | 420 mg | 350 mg |
| China | 330 mg | Not established |
| Japan | 340 mg | 350 mg |
RDA = Recommended Dietary Allowance. UL = Tolerable Upper Intake Level. “Not established” does not mean unlimited intake is safe.
Yes. The U.S. NIH Office of Dietary Supplements sets an adult UL of 350 mg/day for magnesium from supplements and medications; magnesium naturally present in food is excluded. Excess supplemental magnesium can cause diarrhea, nausea, and abdominal cramping, while extremely high intakes can be serious. Kidney impairment can increase risk, so individual review matters.
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