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Can I take magnesium with blood pressure medicine?

Usually yes, with your prescriber's OK. The combination is documented in drug-level studies: in trials of people with high blood pressure who were already on medicine, magnesium lowered systolic pressure 7.68 mm Hg more than placebo did. Thiazide and loop water pills also make you lose magnesium in urine. Kidney disease raises the risk of too much magnesium, so mention it when you ask your prescriber or pharmacist.

How well documented: Documented in drug-level studies. Studies in people measured the effect directly: the medicine’s blood levels or its effect, or a test result.

Last reviewed

How we grade evidenceEditorial policy

What's known

  • Drug-level studies. A 2025 review of 38 trials (2,709 people) found magnesium lowered blood pressure a little overall: 2.81 mm Hg systolic (the top number) and 2.05 diastolic. In trials of people with high blood pressure already taking medicine for it, the fall was larger, 7.68 mm Hg systolic and 2.96 diastolic. Results varied a lot between trials. (Argeros 2025)
  • On the labels: water pills. The hydrochlorothiazide label says thiazides make you lose more magnesium in urine, which can lead to low magnesium. The Lasix (furosemide) label says it may lower blood magnesium and that levels should be checked from time to time. (hydrochlorothiazide label, Lasix label)
  • Amlodipine, losartan and lisinopril. The Norvasc (amlodipine) label reports that antacids with magnesium hydroxide had no impact on amlodipine levels. The Cozaar (losartan) and Zestril (lisinopril) labels don't mention magnesium, but they warn against potassium supplements and potassium salt substitutes without medical advice. (Norvasc label, Cozaar label, Zestril label)
  • Who is at risk. For adults, the upper limit for supplemental magnesium is 350 mg a day. Weak kidneys clear magnesium poorly, which raises the risk of toxicity. Signs include low blood pressure, nausea, vomiting, flushing and an irregular heartbeat. High doses from supplements often cause diarrhea. (ODS)

What to do

  • Talk to your prescriber or pharmacist before you add magnesium, and tell them if you have kidney disease or take a water pill.
  • Check the label of any magnesium product for added potassium, and ask your pharmacist about it if you take losartan or lisinopril.
  • Get medical help for dizziness or fainting, an irregular heartbeat, or vomiting after starting magnesium.
  • If you take a thiazide or loop water pill, ask whether your magnesium level should be checked.
  • Don't stop or change a prescribed medicine on your own.

Sources

  1. Argeros Z, et al. Magnesium Supplementation and Blood Pressure: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Hypertension. 2025. PubMed 41000008 · doi:10.1161/HYPERTENSIONAHA.125.25129
  2. US National Library of Medicine. Hydrochlorothiazide tablets (Teva): prescribing information. DailyMed, revised 07/2024. DailyMed
  3. US National Library of Medicine. Lasix (furosemide) tablets: prescribing information. DailyMed, revised 09/2025. DailyMed
  4. US National Library of Medicine. Norvasc (amlodipine besylate) tablets: prescribing information. DailyMed, revised 02/2023. DailyMed
  5. US National Library of Medicine. Cozaar (losartan potassium) tablets: prescribing information. DailyMed, revised 01/2026. DailyMed
  6. US National Library of Medicine. Zestril (lisinopril) tablets: prescribing information. DailyMed, revised 01/2025. DailyMed
  7. National Institutes of Health, Office of Dietary Supplements. Magnesium: Fact Sheet for Health Professionals. Updated 6 January 2026. ODS