Magnesium Supplements: How to Read Supplement Facts
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The biggest number on the front of a bottle is not enough to compare magnesium supplements. Start with serving size, the magnesium amount per serving and its form.
One serving may contain more than one pill
Serving Size tells you how many pills or how much powder make a serving. Amount Per Serving describes that serving. Do not compare bottles without checking the number of pills per serving.
Elemental magnesium is not compound weight
NIH explains that the magnesium listed in Supplement Facts is elemental magnesium, not the weight of the entire magnesium-containing compound. Absorption differs among forms such as magnesium citrate and magnesium oxide. The name or number alone does not establish which is appropriate for you.
Is 350 mg a daily target?
No. For healthy adults, the daily upper limit for magnesium from supplements and magnesium-containing medicines is 350 mg. Magnesium naturally present in food is excluded from this limit. This is not a dose everyone should try to reach; treatment under medical supervision is assessed separately.
Who should ask first?
Too much supplemental magnesium can cause diarrhea, nausea and abdominal cramps. Impaired kidney function increases the risk of magnesium toxicity. Magnesium can also reduce absorption of certain antibiotics and osteoporosis medicines; spacing depends on the specific medicine. Ask a doctor or pharmacist if you take medicines, have kidney disease, are pregnant or breastfeeding, or are considering it for a child.
Starside Drugs perspective: First establish whether a supplement is needed, then choose the form and dose. This article does not endorse a specific product or replacing a balanced diet with supplements.
Professional sources
Sources checked October 21, 2026. Adapted and updated from previous Starside Drugs social education posts. This is general health education, not individualized medical advice. Follow the complete product label and guidance from your health care professional.