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Medicines and supplements

Magnesium and tetracycline antibiotics such as doxycycline

Written by the Full Measure editorial team, which sells supplements. Approved for publication by the Full Measure owners. Updated .

Drafted with AI assistance from the sources listed below. How we write these

Quick answer

Ask your pharmacist or doctor before combining. Magnesium can keep tetracycline antibiotics such as doxycycline from being absorbed if the two are taken too close together, according to NIH and the doxycycline label. NIH names a second group of antibiotics affected the same way: quinolones such as ciprofloxacin.1,2,3

Key facts

  • NIH names tetracyclines and quinolone antibiotics among the medicines magnesium may interact with.3
  • The doxycycline label says antacids containing aluminum, calcium or magnesium impair the absorption of tetracyclines.2
  • The same label says iron-containing products have this effect too.2
  • Magnesium is in multivitamin and mineral supplements, and in some laxatives and products for heartburn and indigestion.1

Ask your pharmacist how far apart to take them

Tetracycline antibiotics such as doxycycline may not be absorbed if taken too soon before or after a product that contains magnesium. The doxycycline label says antacids containing magnesium impair the absorption of tetracyclines.1,2,3

On the medicine's label

What is documented

NIH's fact sheet for consumers says antibiotics might not be absorbed if taken too soon before or after a dietary supplement that contains magnesium. Its fact sheet for health professionals names the groups: tetracyclines and quinolone antibiotics.1,3

The concern is absorption. Magnesium and the antibiotic bind together in the gut, so less of the antibiotic reaches the blood, and it may not work as well against the infection it was prescribed for.1,2

Which antibiotics this covers

Tetracyclines include doxycycline, minocycline and tetracycline. Quinolones, such as ciprofloxacin and levofloxacin, are named by NIH too, and the ciprofloxacin label lists magnesium antacids among the products that lower its absorption.3,4

Ask your pharmacist how far apart to take them

Magnesium can bind quinolone antibiotics such as ciprofloxacin and levofloxacin in the gut, so less of the antibiotic is absorbed. The ciprofloxacin label lists magnesium and aluminum antacids, multivitamins and other products with minerals such as calcium, iron or zinc among those that lower its absorption.3,4

On the medicine's label

If your antibiotic belongs to another group, such as amoxicillin, the sources on this page do not address it. That is not a finding either way, so ask your pharmacist.

What to ask your pharmacist

  • Is my antibiotic a tetracycline or a quinolone?
  • How far apart should I take it from magnesium, antacids, iron or calcium?
  • Should I pause my supplement while I take the antibiotic?
  • Do my multivitamin, protein powder or electrolyte drink contain magnesium?

Bring the Supplement Facts panel of everything you take. Magnesium can appear in products you would not think of as a magnesium supplement.1

Questions people ask

Can I take magnesium glycinate with doxycycline?

The form does not change the concern. NIH and the label refer to magnesium itself, whatever it is bound to. Ask your pharmacist how to space them.1,2

Does this apply to amoxicillin?

The sources on this page name tetracycline and quinolone antibiotics, not amoxicillin. Ask your pharmacist about your own antibiotic.3

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Sources

  1. Office of Dietary Supplements, National Institutes of Health. Magnesium: Fact Sheet for Consumers. Updated March 22, 2021. Opened 2026-10-06.
  2. Doxycycline hyclate tablets, capsules and oral suspension: prescribing information (Chartwell RX). DailyMed, U.S. National Library of Medicine. Published October 1, 2026. Opened 2026-10-06.
  3. National Institutes of Health, Office of Dietary Supplements. Magnesium: Fact Sheet for Health Professionals. Updated January 6, 2026. Opened 2026-10-06.
  4. Cipro (ciprofloxacin hydrochloride) tablets and oral suspension: prescribing information (Bayer HealthCare Pharmaceuticals). DailyMed, U.S. National Library of Medicine. Label effective March 2, 2026. Opened 2026-10-07.

This page is information, not medical advice. Talk to your doctor or pharmacist about your own situation.