The short answer
Yes, slightly. A meta-analysis of 34 double-blind trials found about 368 mg of magnesium a day for three months lowered blood pressure by around 2 mmHg. The fall was about twice as large in people with insulin resistance, prediabetes or other long-term conditions. It is not a substitute for blood pressure medicine.
Moderate evidence
More than one placebo-controlled trial points the same way, but the trials are small, short or mixed in quality. How we grade
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What did the blood pressure trials find?
The most thorough analysis, published in Hypertension in 2016, pooled 34 randomised, double-blind, placebo-controlled trials with 2,028 participants. A median of 368 mg of magnesium a day for a median of three months:
- lowered systolic blood pressure (the top number) by 2.0 mmHg
- lowered diastolic blood pressure (the bottom number) by 1.8 mmHg
- raised blood magnesium slightly, by 0.05 mmol/L
A dose of 300 mg a day, or a duration of one month, was enough to see the effect. Better-quality trials tended to find bigger falls.
Who benefits most from magnesium for blood pressure?
A second meta-analysis in 2017 looked only at 11 trials in 543 people with insulin resistance, prediabetes or other long-term conditions such as type 2 diabetes. Here, 365 to 450 mg a day lowered systolic pressure by 4.2 mmHg and diastolic by 2.3 mmHg. These are people who are more likely to be short of magnesium, which fits the pattern seen across the research (see signs of low magnesium).
Is 2 mmHg worth having?
For one person, it is a small change, and you probably wouldn’t notice it on a home monitor. Across a population, small falls add up: lowering blood pressure by a few points reduces the risk of strokes and heart attacks. But for anyone with high blood pressure, medicines and lifestyle changes such as cutting salt, losing weight, drinking less alcohol and being more active have much larger effects.
How would you take magnesium for blood pressure?
If you want to add magnesium:
- Aim for 300 to 400 mg of elemental magnesium a day, ideally from a mix of food and supplement. Food sources such as seeds, nuts, beans and wholegrains also bring potassium and fibre, which help blood pressure too.
- Tell your GP or pharmacist, particularly if you take diuretics, which change how much magnesium you lose. See medicines and magnesium.
- Don’t take magnesium supplements if you have kidney disease unless your doctor advises it.
Which form is best for blood pressure?
No form has been shown to work better than another. The trials used citrate, oxide, chloride, lactate, aspartate and others. A well-absorbed form taken every day is a sensible choice: see types of magnesium compared and dosage and timing.
What doesn’t the evidence show?
That magnesium can replace blood pressure medicine, or that it reduces heart attacks and strokes. The trials measured blood pressure, not those outcomes, and they lasted months, not years.
Keep reading
- Magnesium for constipation: how it works and how to take it
Magnesium salts are proven osmotic laxatives. How magnesium oxide and other forms relieve constipation, how much to take, and when to avoid them.
Strong - Magnesium for restless legs: does it help?
Magnesium is a popular remedy for restless legs syndrome. One small trial suggests it may help; a systematic review could not say. The evidence, graded.
Weak - Magnesium for blood sugar and type 2 diabetes: the evidence
Can magnesium lower blood sugar? What the trials found in type 2 diabetes and prediabetes, who gains most, and how to take it safely alongside treatment.
Moderate
Common questions
Can I stop my blood pressure tablets if I take magnesium?
No. A 2 to 4 mmHg fall is far smaller than most blood pressure medicines achieve. Never stop or change prescribed treatment without talking to your GP or pharmacist.
Is magnesium safe with blood pressure tablets?
Usually, but check with your pharmacist. Some diuretics change how your body handles magnesium: loop and thiazide diuretics increase losses, while potassium-sparing diuretics such as amiloride and spironolactone reduce them.
How much magnesium lowers blood pressure?
The meta-analysis found 300 mg a day for a month was enough to see an effect. The median dose in the trials was 368 mg a day.
How long does magnesium take to lower blood pressure?
In the trials, about a month at 300 mg a day was enough to see an effect, with most lasting around three months. The fall is small, about 2 mmHg on average.
References
- Zhang X et al. Effects of magnesium supplementation on blood pressure: a meta-analysis of randomized double-blind placebo-controlled trials. Hypertension, 2016.pubmed.ncbi.nlm.nih.gov
- Dibaba DT et al. The effect of magnesium supplementation on blood pressure in individuals with insulin resistance, prediabetes, or noncommunicable chronic diseases: a meta-analysis of randomized controlled trials. American Journal of Clinical Nutrition, 2017.pubmed.ncbi.nlm.nih.gov
- Kass L et al. Effect of magnesium supplementation on blood pressure: a meta-analysis. European Journal of Clinical Nutrition, 2012.pubmed.ncbi.nlm.nih.gov
- National Institutes of Health Office of Dietary Supplements. Magnesium: fact sheet for health professionals.ods.od.nih.gov
First published 4 November 2026. Spotted an error? Tell us and we'll correct it. Read our editorial policy.