# Magnesium and medicines: interactions to know about

Source: https://magnesiumguide.uk/safety/drug-interactions/
Author: Nell Hartley · Updated 2026-11-04

**Short answer:** Magnesium can stop some medicines being absorbed if taken at the same time, including tetracycline and quinolone antibiotics, bisphosphonates for osteoporosis and levothyroxine, so leave a gap of a few hours. Some medicines lower magnesium, especially long-term proton pump inhibitors and loop or thiazide diuretics. Ask your pharmacist if you take regular medicines.

## Which medicines does magnesium block?

In the gut, magnesium binds to some medicines and forms compounds the body can't absorb, which can make them work less well. Leave a gap between magnesium (and antacids or laxatives containing it) and:

| Medicine | Examples | What to do |
| --- | --- | --- |
| Tetracycline antibiotics | doxycycline, lymecycline, minocycline | Keep a gap of several hours; follow the leaflet |
| Quinolone antibiotics | ciprofloxacin, levofloxacin | Take the antibiotic at least 2 hours before or 4 to 6 hours after magnesium |
| Bisphosphonates | alendronic acid, risedronate | Take magnesium at least 2 hours after the bisphosphonate |
| Levothyroxine | thyroid replacement | The NHS lists antacids and indigestion remedies among medicines that affect it; keep magnesium several hours apart |

The patient information leaflet with each medicine gives the exact gap.

## Which medicines lower magnesium?

| Medicine | Effect |
| --- | --- |
| Proton pump inhibitors (omeprazole, lansoprazole, esomeprazole, pantoprazole) | Long-term use, usually over a year, can cause low magnesium, sometimes severe. The MHRA advises doctors to consider measuring magnesium before and during long-term treatment. |
| Loop diuretics (furosemide, bumetanide) and thiazides (bendroflumethiazide, indapamide) | Increase magnesium lost in urine |
| Some cancer medicines and some antibiotics given in hospital | Can lower magnesium; your specialist team will monitor this |

If you take one of these long term, ask your GP whether you should have a [magnesium blood test](/basics/magnesium-blood-test/) before starting a supplement. [Signs of low magnesium](/basics/deficiency-symptoms/) lists the symptoms to watch for.

## Which medicines raise magnesium?

Potassium-sparing diuretics, such as amiloride and spironolactone, reduce how much magnesium the kidneys release. Combined with supplements or kidney problems, this could push levels too high, so check with your doctor.

## Can you take magnesium with calcium, zinc, iron or vitamin D?

Usually yes. A few practical points:

- **Zinc.** Very high doses of zinc, well above the amounts in most supplements, can reduce magnesium absorption. Normal multivitamin doses are fine.
- **Calcium and iron.** Large doses taken at exactly the same time may compete a little for absorption. If you take separate high-dose supplements, spacing them out is a simple fix.
- **Vitamin D.** No problem. The body needs magnesium to process vitamin D, which is one reason the two are often sold together.

[How to take magnesium](/how-to-take/) covers timing and combinations in more detail.

## What else should you watch for?

- **Other sources of magnesium.** Antacids, laxatives such as milk of magnesia, and many multivitamins contain magnesium. Count them all.
- **Kidney disease.** This changes everything about magnesium safety. Don't take supplements unless your doctor advises it. See [side effects](/safety/side-effects/) for the signs of too much.
- **Blood pressure medicines.** Magnesium can lower blood pressure slightly, by about 2 mmHg in trials, which is rarely a problem but worth mentioning to your GP. See [magnesium and blood pressure](/benefits/blood-pressure/).

If you take any regular medicine, ask your pharmacist before starting magnesium. It takes a couple of minutes and is free.

## Frequently asked questions

### How long should I leave between magnesium and my medicine?

It depends on the medicine. Commonly it is at least 2 hours before or 4 to 6 hours after for some antibiotics, and at least 2 hours after bisphosphonates such as alendronic acid. The patient leaflet or your pharmacist will tell you the exact gap.

### Can I take magnesium with omeprazole?

Yes, there is no harmful interaction. In fact, long-term omeprazole and similar medicines can lower magnesium, and the MHRA advises doctors to consider checking magnesium levels in people on them for a long time. Ask your GP before starting a supplement.

### Can I take magnesium with blood pressure medicine?

Usually, but tell your pharmacist. Magnesium lowers blood pressure slightly. Loop and thiazide diuretics increase magnesium losses, while potassium-sparing diuretics such as amiloride and spironolactone reduce them.

### Can I take magnesium with vitamin D?

Yes. There's no harmful interaction, and the body needs magnesium to activate vitamin D. Many combined products are available.

## References

1. [MHRA. Proton pump inhibitors in long-term use: reports of hypomagnesaemia. Drug Safety Update, 2012.](https://www.gov.uk/drug-safety-update/proton-pump-inhibitors-in-long-term-use-reports-of-hypomagnesaemia)
2. [National Institutes of Health Office of Dietary Supplements. Magnesium: fact sheet for health professionals (interactions with medications).](https://ods.od.nih.gov/factsheets/Magnesium-HealthProfessional/)
3. [NHS. Levothyroxine: taking it with other medicines.](https://www.nhs.uk/medicines/levothyroxine/)
4. [NHS. Omeprazole.](https://www.nhs.uk/medicines/omeprazole/)
5. [NHS. Furosemide.](https://www.nhs.uk/medicines/furosemide/)