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How much magnesium should you take?

The recommended dietary allowance (RDA) includes the magnesium you get from both the food you eat and any supplements you take.


Recommended Dietary Allowance (RDA)


1-3 years

80 mg/day

4-8 years

130 mg/day

9-13 years

240 mg/day


14-18 years

360 mg/day

19-30 years

310 mg/day

31 years and over

320 mg/day


Under 19 years: 400 mg/day

19 to 30 years: 350 mg/day

31 years and up: 360 mg/day


Under 19 years: 360 mg/day

19 to 30 years: 310 mg/day

31 years and up: 320 mg/day


14-18 years

410 mg/day

19-30 years

400 mg/day

31 years and up

420 mg/day

It's safe to get high levels of magnesium from food. But excessive use of magnesium supplements can be toxic. The upper limit -- the highest dose a person can take -- of magnesium supplements is:

  • 65 mg/day for children ages 1-3
  • 110 mg/day for children ages 4-8
  • 350 mg/day for adults and children ages 9 and up

Can you get magnesium naturally from foods?

Natural food sources of magnesium include:

  • Green, leafy vegetables, like spinach
  • Nuts
  • Beans, peas, and soybeans
  • Whole-grain cereals

Eating whole foods is always best. Magnesium can be lost during refinement and processing.

What are the risks of taking magnesium?

  • Side effects. Magnesium supplements can cause nausea, cramps, and diarrhea. Magnesium supplements often cause softening of stool.
  • Interactions. Magnesium supplements may not be safe for people who take diuretics, heart medicines, or antibiotics. Check with your health care provider if you are taking any medicine before taking magnesium.
  • Risks. People with diabetes, intestinal disease, heart disease or kidney disease should not take magnesium before speaking with their health care provider.
  • Overdose. Signs of a magnesium overdose can include nausea, diarrhea, low blood pressure, muscle weakness, and fatigue. At very high doses, magnesium can be fatal.

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