“Never Use Magnesium If You Take These Medications” — The Safer Truth
The word “never” is too strong. Magnesium supplements can interfere with some medicines, but in many cases the solution is to separate the doses rather than avoid magnesium altogether. Magnesium naturally found in food is generally safe for healthy people.
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Office of Dietary Supplements
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Medicines that deserve special attention
Tetracycline antibiotics — such as doxycycline. Magnesium can bind the drug and reduce how much your body absorbs.
Quinolone antibiotics — including ciprofloxacin and levofloxacin. These should generally be taken at least 2 hours before or 4–6 hours after a magnesium supplement.
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Office of Dietary Supplements
Oral bisphosphonates — such as alendronate, used to treat osteoporosis. Magnesium can reduce their absorption; separating the doses by at least 2 hours can help.
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Office of Dietary Supplements
Diuretics (“water pills”) — furosemide and hydrochlorothiazide can increase magnesium losses, while some potassium-sparing diuretics can have the opposite effect. Your doctor may need to monitor your magnesium level.
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Office of Dietary Supplements
Proton-pump inhibitors (PPIs) — long-term use of medicines such as omeprazole or lansoprazole can lower magnesium levels. In some people, supplementation is needed; others may need their PPI treatment reviewed.
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Office of Dietary Supplements
Some thyroid medicines and other drugs — magnesium can interfere with absorption of certain medications. Because the exact timing depends on the medicine, ask your pharmacist about spacing rather than guessing.
If you’re over 70 or have kidney problems
Extra caution is important. Healthy kidneys remove excess magnesium, but impaired kidney function can allow magnesium to accumulate. High doses from supplements or magnesium-containing laxatives/antacids can cause diarrhea and, at very high levels, low blood pressure, breathing difficulties, abnormal heart rhythm, and cardiac arrest.
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Office of Dietary Supplements
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For adults, the NIH’s upper limit for magnesium from supplements and medications is generally 350 mg per day, unless a healthcare professional recommends otherwise. This limit does not include magnesium naturally present in food.
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Office of Dietary Supplements
Bottom line: Don’t stop a prescribed medication or automatically avoid magnesium. Before starting a supplement, have a pharmacist review your prescription drugs, over-the-counter medicines, antacids, laxatives, and supplements for interactions.
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