Can I take magnesium with doxycycline?

ODS says magnesium binds tetracyclines such as doxycycline and that the antibiotic should be taken at least 2 hours before or 4 to 6 hours after a magnesium supplement.

How long after zinc can I take ciprofloxacin?

ODS says to take quinolones such as ciprofloxacin at least 2 hours before or 4 to 6 hours after a zinc supplement.

Does calcium affect antibiotics?

ODS says calcium supplements can reduce absorption of quinolones such as ciprofloxacin, and that taking the antibiotic 2 hours before or after calcium prevents this.

Do antacids affect antibiotics?

Many antacids contain magnesium or calcium, which ODS says can bind tetracyclines and quinolones. Ask your pharmacist how to time them with your antibiotic.

Magnesium, Zinc or Calcium With Antibiotics: Timing

Short answer: Not at the same time for two antibiotic families. NIH fact sheets say magnesium, zinc and calcium can bind tetracyclines (such as doxycycline) and quinolones (such as ciprofloxacin) in the gut and lower absorption. They say to take the antibiotic at least 2 hours before or 4 to 6 hours after magnesium or zinc, and 2 hours before or after calcium. Your prescriber or pharmacist can say what fits your antibiotic.

Why minerals and these antibiotics clash

The NIH Office of Dietary Supplements (ODS) says magnesium forms insoluble complexes with tetracyclines and quinolone antibiotics, meaning the two stick together in the gut and less of the antibiotic is absorbed. It says zinc can interact the same way, which can lower absorption of both the zinc and the antibiotic. For calcium, ODS says taking it at the same time as a quinolone can reduce how much of the antibiotic is absorbed.

Less antibiotic in the blood can mean it works less well against the infection, which is why the timing advice is about the antibiotic, not the supplement.

The timing gaps ODS gives

Antibiotic timing around mineral supplements, from the NIH ODS fact sheets
Mineral	Antibiotics named	Gap ODS describes
Magnesium	Tetracyclines (demeclocycline, doxycycline); quinolones (ciprofloxacin, levofloxacin)	Antibiotic at least 2 hours before or 4 to 6 hours after
Zinc	Quinolones (such as Cipro); tetracyclines (such as Achromycin, Sumycin)	Antibiotic at least 2 hours before or 4 to 6 hours after
Calcium	Quinolones (ciprofloxacin, gemifloxacin, moxifloxacin)	Antibiotic 2 hours before or 2 hours after

Antibiotic labels can set their own timing, which may differ from these figures, so the label or pharmacist for the specific antibiotic is the final word. Antacids and multivitamins often contain magnesium, calcium or zinc, so they raise the same question. Combination products such as ZMA contain both zinc and magnesium.

Other medicines with the same issue

The same binding problem shows up with other medicines in the ODS fact sheets:

Oral bisphosphonates such as alendronate (Fosamax): ODS says magnesium-rich supplements or medicines can lower their absorption and suggests at least 2 hours apart. See calcium and Fosamax.
Levothyroxine: the ODS calcium sheet says calcium carbonate can interfere with absorption, with a 4-hour gap in the label. See calcium and iron with levothyroxine.
Dolutegravir (an HIV medicine): ODS says its labels advise taking it 2 hours before or 6 hours after calcium supplements.
Penicillamine: ODS says zinc can reduce its absorption and to take them at least 1 hour apart.

Medicines that lower mineral levels

Some interactions run the other way. ODS says loop and thiazide diuretics can increase magnesium loss in urine, and thiazide diuretics increase zinc loss. It says long-term proton pump inhibitor use (typically more than a year) can cause low magnesium; in cases the FDA reviewed, supplements raised magnesium in most, but in 25% the person had to stop the PPI.

A short course of antibiotics is easy to forget when a supplement routine runs on autopilot. Dose Track can set separate reminder times for the antibiotic and the supplement so the gap holds for the length of the course.

Read more on Dose Track: Magnesium glycinate · Zinc · Calcium supplements · ZMA · Multivitamins

General education drawn from labels, public health agencies and published studies, not personal medical advice. Your prescriber, pharmacist and the label that came with your medicine are the final word. Questions for other users? Ask in the Dose Track community.

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