500 mg of elemental magnesium is more than the usual safe upper limit for daily magnesium supplements. Reviewed on ****, the U.S. National Institutes of Health lists 350 mg per day as the upper limit for magnesium from supplements and magnesium-containing medicines for adults. This limit does not include magnesium naturally found in food.
The number on a magnesium glycinate bottle can be confusing. "500 mg" may refer to the amount of magnesium itself, or to the total weight of the magnesium glycinate compound. Check the Supplement Facts panel before deciding whether the dose is high.
Check Whether the 500 mg Is Elemental Magnesium
| What the label says | What it means |
|---|---|
| "Magnesium 500 mg, as magnesium glycinate" | This usually means 500 mg of elemental magnesium, which is above the adult upper limit for supplements. |
| "Magnesium glycinate 500 mg" | This may refer to the total weight of the compound. The elemental magnesium amount may be much lower. |
| "Magnesium 100 mg, as magnesium glycinate" | This means the product provides 100 mg of elemental magnesium. Count this amount toward your daily supplement intake. |
The NIH explains that the Supplement Facts panel lists the amount of elemental magnesium, not the total weight of the magnesium-containing compound.
Is 500 mg of Elemental Magnesium Glycinate Safe Daily?
For a healthy adult, 500 mg of elemental magnesium from a supplement is above the recommended upper limit. Do not take that amount routinely unless a healthcare professional recommends it.
Adults generally need about 310 to 420 mg of magnesium per day from all sources, including food. That recommendation is different from the 350 mg upper limit, which applies only to magnesium from supplements and medicines.
Too much supplemental magnesium can cause:
- Diarrhea
- Nausea
- Abdominal cramping
- Vomiting
Very high magnesium levels can cause low blood pressure, muscle weakness, breathing difficulty, abnormal heart rhythms and cardiac arrest.
What If You Already Took 500 mg Once?
If you are a healthy adult, took one dose and feel well, do not take more magnesium that day. Watch for diarrhea, nausea, abdominal cramping and vomiting.
A single dose is not automatically a medical emergency. The risk is higher if the product provided 500 mg of elemental magnesium rather than 500 mg of the magnesium glycinate compound.
Contact a healthcare professional or Poison Control for advice if you:
- Have kidney disease or reduced kidney function
- Took multiple doses
- Used magnesium from several products, including supplements, laxatives or antacids
- Are pregnant or breastfeeding
- Take prescription medicines that may interact with magnesium
In the United States, Poison Control can be reached at 1-800-222-1222. Seek emergency care for severe weakness, confusion, fainting, trouble breathing, an irregular heartbeat, persistent vomiting or inability to wake someone.
Who Should Avoid High-Dose Magnesium Without Medical Advice?
People with kidney disease need particular caution. The kidneys remove excess magnesium, so reduced kidney function can allow magnesium to build up in the body and increase the risk of toxicity.
Magnesium can also interfere with some medicines, including:
- Oral bisphosphonates, such as alendronate
- Tetracycline antibiotics, such as doxycycline
- Quinolone antibiotics, such as ciprofloxacin and levofloxacin
These medicines may need to be taken several hours apart from magnesium. Ask a pharmacist about the correct schedule for your prescription.
Bottom Line
Check the elemental magnesium amount in the Supplement Facts panel.
- 500 mg of elemental magnesium daily is generally too much for routine self-supplementation.
- A product containing 500 mg of magnesium glycinate compound may provide much less elemental magnesium.
- People with kidney problems or those taking interacting medicines should seek medical advice before using high-dose magnesium.