Magnesium and Medicines: Antibiotics, Bisphosphonates, Thyroid Medicine, Diuretics and Acid Reducers
How magnesium supplements, antacids and laxatives can affect some antibiotics, bone medicines and thyroid medicine, and how diuretics and acid reducers can lower magnesium.
Content last updated . This page has not been medically reviewed.
Quick answer
Magnesium works in two directions with medicines. Magnesium in supplements, antacids and laxatives can bind to or interfere with some medicines taken by mouth. And some medicines, such as water pills (diuretics) and long-term acid reducers, can lower the body's magnesium. [1] Do not stop or change a prescribed medicine because of this page. A pharmacist can check your exact medicines and the right gap between them.
Medicines that magnesium products can interfere with
| Medicine group | What the sources say |
|---|---|
| Tetracycline antibiotics | MedlinePlus says antacids, calcium supplements, zinc products and laxatives containing magnesium should be taken 6 hours before or 2 hours after tetracycline [2]. For doxycycline, the NHS lists antacids, indigestion treatments, and iron or zinc products as things that may not mix well [3], and MedlinePlus advises separating antacids and magnesium laxatives from it [4] |
| Ciprofloxacin (a quinolone antibiotic) | MedlinePlus says antacids or multivitamins containing calcium, magnesium hydroxide, aluminum hydroxide, zinc or iron should be taken at least 6 hours before or 2 hours after it [5] |
| Bisphosphonates (osteoporosis medicines) | The NHS says other oral medicines should be kept apart from alendronic acid by at least 30 minutes and asks people to tell their doctor about magnesium laxatives, antacids and supplements containing calcium, iron, magnesium or zinc [6]. MedlinePlus lists milk of magnesia among antacids that may interact with alendronate [7] |
| Thyroid medicine (levothyroxine) | The NHS lists antacids, indigestion treatments, and calcium and iron supplements as things that may not mix well [8]. MedlinePlus lists antacids and says to separate calcium carbonate or iron by at least 4 hours [9]. A specific magnesium supplement is not named on the pages we read |
| Digoxin and some other antibiotics | EFSA's 2006 review mentions possible interactions of magnesium with certain drugs including tetracycline, penicillin and digoxin, citing an older source [10] |
On why gaps matter, the NHS says other medicines taken by mouth can react with alendronic acid and stop it working properly. [6] The gaps differ by medicine, so a pharmacist should confirm the one for yours.
Medicines that can lower magnesium
- Diuretics (water pills). MedlinePlus lists diuretics among medicines that can decrease magnesium levels. [1] A review states that magnesium depletion in clinical practice is mainly related to loop diuretics and thiazides, and that more than a third of patients treated with diuretics had low magnesium. [11] Other kinds of diuretics are not described in the sources we read.
- Acid reducers (proton pump inhibitors). The omeprazole drug label says low magnesium has been reported rarely after at least three months of use, usually after a year, with serious events including tetany, arrhythmias and seizures. [12] In most cases treatment needed magnesium replacement and stopping the drug, which is a clinician's decision. [12] A case report describes a woman with a fast heart rhythm from low magnesium while using lansoprazole. [13]
- Certain antibiotics. MedlinePlus lists certain antibiotics among medicines that can lower magnesium; which ones are not stated. [1]
Medicines that can raise magnesium
MedlinePlus lists medicines containing magnesium (laxatives and certain antacids), aspirin and lithium as medicines that can increase magnesium levels. [1] Combined with kidney disease this can matter; see magnesium side effects, toxicity and kidney disease.Frequently asked questions
Can I take magnesium with antibiotics?
It depends on the antibiotic. MedlinePlus gives separate time gaps for tetracycline (6 hours before or 2 hours after) and ciprofloxacin (at least 6 hours before or 2 hours after). [2][5] A pharmacist can confirm for your prescription.
Does magnesium interfere with levothyroxine?
Levothyroxine drug pages warn about antacids and calcium or iron supplements. [8][9] A magnesium supplement is not named on the pages we read, so ask a pharmacist.
Do magnesium antacids affect osteoporosis medicine?
The NHS asks people taking alendronic acid to tell their doctor about antacids and magnesium laxatives or supplements. [6]
Do water pills or acid reducers lower magnesium?
Diuretics and proton pump inhibitors can, according to MedlinePlus and the omeprazole label. [1][12]
Should I stop my medicine if I take magnesium?
No. Never stop or change a prescribed medicine without your prescriber's advice.
More details: evidence, limits and cautions
The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.
How to read this page
We use these labels: documented in drug information (a health agency or drug label says so), case or review evidence, not described in the sources we read. The gaps below are the ones those drug pages give, not personal schedules, and they differ by medicine.
Safety and who should ask first
- Always check with a pharmacist before starting a magnesium supplement if you take any prescription medicine. See Medication Interactions and spacing supplements and medicines.
- Antacid products count. A magnesium-containing antacid is a source of magnesium as well as a possible interaction. See minerals and stomach acid.
- Pregnancy, breastfeeding, children, older adults: interaction data for these groups are not described in the sources we read; ask a clinician or pharmacist. Older adults who take many medicines can use minerals for older adults and polypharmacy.
- Kidney or liver disease and surgery: tell the care team about every supplement and antacid.
- Quality: labels list elemental magnesium; see quality testing and certifications.
More mineral and medicine pairings are collected in the mineral and medicine interactions reference.
References
- MedlinePlus (US National Library of Medicine). MedlinePlus, Magnesium Blood Test.
- MedlinePlus Drug Information (US National Library of Medicine). Last revised 06/15/2026. MedlinePlus, Tetracycline.
- NHS (UK). Page last reviewed 5 September 2025. NHS, Taking doxycycline with other medicines.
- MedlinePlus Drug Information (US National Library of Medicine). Last revised 05/15/2026. MedlinePlus, Doxycycline.
- MedlinePlus Drug Information (US National Library of Medicine). Last revised 08/15/2026. MedlinePlus, Ciprofloxacin.
- NHS (UK). Page last reviewed 7 May 2025. NHS, Taking alendronic acid with other medicines and herbal supplements.
- MedlinePlus Drug Information (US National Library of Medicine). Last revised 05/15/2026. MedlinePlus, Alendronate.
- NHS (UK). Page last reviewed 6 July 2026. NHS, Levothyroxine.
- MedlinePlus Drug Information (US National Library of Medicine). Last revised 02/15/2019. MedlinePlus, Levothyroxine.
- European Food Safety Authority / Scientific Committee on Food. February 2006. Tolerable Upper Intake Levels for Vitamins and Minerals, magnesium chapter.
- Hypomagnesemia and cardiovascular system. Hippokratia 2006. PubMed 22087052. Abstract read 2026-10-23.
- US Food and Drug Administration, approved prescribing information for an omeprazole product (label version 2012), section 5.6 Hypomagnesemia. FDA label, Drugs@FDA. Read 2026-10-23.
- Lansoprazole-induced hypomagnesaemia. BMJ Case Reports 2014. PubMed 24414180. Abstract read 2026-10-23.
Education, not medical advice. This page is for general information. It does not diagnose or treat any condition and is not a substitute for care from a qualified health professional. Natural does not automatically mean safe. Ask a clinician or pharmacist before changing your care, especially if you take medication, are pregnant or breastfeeding, or have a health condition.