Does magnesium lower blood pressure?

A little. In a 2025 meta-analysis of 38 randomized trials with 2709 adults, magnesium supplements lowered systolic pressure by 2.81 mm Hg (95% CI 1.29 to 4.32) and diastolic by 2.05 mm Hg (0.88 to 3.23) against placebo. The median dose was 365 mg a day for a median 12 weeks. In subgroup analyses the drop was larger in people with high blood pressure already on medication and in people with low blood magnesium. In people with normal blood pressure the drop was not significant.

Unsettled. The pooled effect is real on paper and shaky underneath. Only 9 of those 38 trials were at low risk of bias, and results varied widely between them (I2 78 percent for systolic pressure). A 2006 Cochrane review of 12 trials in 545 people with high blood pressure judged the evidence for a causal effect weak and probably due to bias. Larger reviews since then keep finding a small effect, and the same worries about trial quality.

What the trials found

The overall number is small

Three pooled analyses land in the same narrow range. The 2025 review found 2.81 mm Hg systolic. A 2016 meta-analysis of 34 double-blind placebo-controlled trials with 2028 adults found that a median 368 mg a day for 3 months lowered systolic pressure by 2.00 mm Hg (0.43 to 3.58) and diastolic by 1.78 mm Hg (0.73 to 2.82). A 2026 dose-response analysis of 78 trials also reported a lower blood pressure among several heart and metabolic markers, and its authors call the effects modest with uncertain clinical relevance.

The Cochrane review, limited to people with high blood pressure and trials of 8 to 26 weeks, found diastolic pressure fell by 2.2 mm Hg (0.9 to 3.4). Systolic pressure fell by 1.3 mm Hg, and that did not reach significance.

Where the effect is larger

In the 2025 review, people with high blood pressure who were already on blood pressure drugs saw systolic pressure fall by 7.68 mm Hg (2.69 to 12.67), in a subgroup of 6 trials. Those who were untreated saw a change of 0.90 mm Hg, which was not significant (P 0.56). Diuretic-treated patients often lose magnesium, so part of that larger effect may be topping up a shortfall.

People with low serum magnesium, 0.74 mmol/L or lower, saw systolic pressure fall by 5.97 mm Hg (3.41 to 8.52) across 8 trials. People with normal serum magnesium saw no significant change. Serum magnesium is a weak marker of what the body holds, and this is a subgroup analysis.

In people with insulin resistance, prediabetes or other chronic disease, 11 trials with 543 people at 365 to 450 mg a day for 1 to 6 months found a mean fall of 4.18 mm Hg systolic and 2.27 mm Hg diastolic. In type 2 diabetes, seven trials found 5.78 mm Hg systolic (0.19 to 11.37), and the lower end of that interval sits close to zero.

One 6-month double-blind trial in women aged 40 to 65 with high blood pressure on hydrochlorothiazide gave 600 mg a day of magnesium chelate. In the magnesium group office pressure went from 144/88 to 134/81 mm Hg. Those are changes within the group, the abstract does not state how many women took part, and the trial was small and single-center.

People with normal blood pressure

Unsettled. The 2025 review found no significant fall in systolic or diastolic pressure among people with normal blood pressure, from few trials. A 2023 meta-analysis of normotensive trials found a drop of 2.79/1.56 mm Hg. Two reviews pointing in different directions on few trials is why this part of the answer is open.

Blood magnesium and hypertension in observational data

The data here come from 3 cohort and 19 cross-sectional studies with 58,432 people. Those with the highest circulating magnesium had 35 percent lower odds of hypertension than those with the lowest (OR 0.65, 0.56 to 0.76), with large differences between studies. These are odds from mostly cross-sectional data, there is no absolute risk to set beside them, and they cannot show that magnesium causes the difference.

Who should be careful

Not for everyone. Kidney disease changes the picture. NIH warns that the risk of magnesium toxicity rises with impaired kidney function or kidney failure, because the excess can no longer be cleared. Kidney disease and high blood pressure often come together, so this applies to many of the people most likely to try it.

NIH sets the upper limit for magnesium from supplements at 350 mg a day for adults, and 65 to 350 mg for children and teens depending on age. Magnesium in food does not count toward it. The blood pressure reviews used a median of 365 to 368 mg a day, around that limit, and the hydrochlorothiazide trial used 600 mg.

Magnesium can interact with oral bisphosphonates and with tetracycline and quinolone antibiotics. Diuretics and proton pump inhibitors can change magnesium status. Diuretics are among the first drugs used for high blood pressure, which ties this caution to the group where the effect looked largest.

In a double-blind trial of 200 healthy first-time pregnant women, daily magnesium did not prevent the rise in blood pressure, and the authors concluded it is not to be recommended for that purpose. The abstract gives no dose.

What expert bodies say

The US National Institutes of Health says that studies to date show magnesium supplements only marginally lower blood pressure. In 2022 the FDA approved a qualified health claim that adequate magnesium may reduce the risk of high blood pressure, for foods and supplements with at least 84 mg per serving and supplements of no more than 350 mg. A qualified claim is the kind allowed while the evidence is limited, and it is not an endorsement. We did not read the 2025 American hypertension guideline itself, and the summaries of its lifestyle advice we found do not name magnesium.

How we searched

What would change this answer

• A well-run trial in people with raised blood pressure who take no medication, the group where the 2025 review found no systolic effect. One is under way: a 12-week trial of magnesium glycinate against placebo in 120 adults with elevated systolic pressure, due to finish in December 2026.
• Trials that recruit people who are low in magnesium on purpose. Everything above points to the effect living there, and most trials did not select for it.
• Better trials overall. With most trials raising some concern for bias and wide differences between them, a few large, well-reported trials would count for more than another pooling of the same ones.

The rest of what magnesium does, including sleep, is on the magnesium and sleep page.

Sources

1. ev-mgbp-01 · Meta-analysis or systematic review · systematic review and meta-analysis of randomized controlled trials · n = 2709
   Magnesium intake resulted in a reduction in systolic BP of -2.81 mm Hg (95% CI, -4.32 to -1.29) and diastolic BP by -2.05 mm Hg (95% CI, -3.23 to -0.88) compared with placebo.
   
   Who: adults in randomized controlled trials of magnesium supplementation lasting 4 weeks or more, hypertensive and normotensive
   Effect: SBP -2.81 mm Hg (95% CI -4.32 to -1.29); DBP -2.05 mm Hg (95% CI -3.23 to -0.88); median dose 365 mg elemental, median 12 weeks; no dose-response
   Certainty: High heterogeneity (I2 78% SBP, 88% DBP); 9 of 38 trials at low risk of bias.
   Hypertension, 2025 · checked 2026-10-06 · we read the abstract
2. ev-mgbp-02 · Meta-analysis or systematic review · systematic review and meta-analysis of randomized controlled trials, subgroup analysis · n = 15 trials
   In participants with hypertension, magnesium intervention lowered SBP for those on BP-lowering medication by −7.68 mm Hg (95% CI, −12.67 to −2.69; P=0.003) but no changes were observed among those untreated, −0.90 mm Hg (95% CI, −3.94 to 2.14; P=0.56).
   
   Who: participants with hypertension, on BP-lowering medication (6 trials) or untreated (9 trials)
   Effect: SBP on medication -7.68 mm Hg (95% CI -12.67 to -2.69); untreated -0.90 mm Hg (95% CI -3.94 to 2.14, P=0.56)
   Certainty: Subgroup of 6 trials; diuretic-treated patients often lose magnesium, so part of the effect may be repletion.
   Hypertension, 2025 · checked 2026-10-06 · we read the fulltext
3. ev-mgbp-03 · Meta-analysis or systematic review · systematic review and meta-analysis of randomized controlled trials, subgroup analysis · n = 8 trials
   Magnesium intervention did not produce significant reductions in SBP and DBP among participants with normotension.
   
   Who: participants with normotension (8 trials)
   Effect: no significant SBP or DBP reduction in normotension; hypertension SBP -2.96 mm Hg (95% CI -5.53 to -0.38)
   Certainty: Few normotensive trials; a 2023 meta-analysis of normotensive trials (37836507) did find -2.79/-1.56 mm Hg, so the normotensive answer is unsettled.
   Hypertension, 2025 · checked 2026-10-06 · we read the fulltext
4. ev-mgbp-04 · Meta-analysis or systematic review · systematic review and meta-analysis of randomized controlled trials, subgroup analysis · n = 8 trials with hypomagnesemia
   Among participants with hypomagnesemia, magnesium intervention reduced SBP by −5.97 mm Hg (95% CI, −8.52 to −3.41; P<0.001).
   
   Who: trial participants with hypomagnesemia (serum magnesium 0.74 mmol/L or lower) versus normomagnesemia
   Effect: SBP -5.97 mm Hg (95% CI -8.52 to -3.41); DBP -4.75 mm Hg (95% CI -6.59 to -2.92); no significant change with normal serum magnesium
   Certainty: Subgroup analysis; serum magnesium is a weak marker of body stores.
   Hypertension, 2025 · checked 2026-10-06 · we read the fulltext
5. ev-mgbp-05 · Meta-analysis or systematic review · systematic review and meta-analysis of randomized controlled trials, risk of bias assessment · n = 38 trials
   Of all studies included in the meta-analysis, 9 were evaluated as low risk, 25 as some concern, and 4 as high risk.
   
   Who: 38 randomized controlled trials of magnesium and blood pressure
   Effect: risk of bias: 9 low, 25 some concerns, 4 high; I2 78% (SBP), 88% (DBP); no funnel asymmetry (Egger P=0.52 SBP)
   Certainty: Most concerns came from unreported randomization and allocation concealment.
   Hypertension, 2025 · checked 2026-10-06 · we read the fulltext
6. ev-mgbp-06 · Meta-analysis or systematic review · meta-analysis of randomized double-blind placebo-controlled trials · n = 2028
   Mg supplementation at a median dose of 368 mg/d for a median duration of 3 months significantly reduced systolic BP by 2.00 mm Hg (95% confidence interval, 0.43-3.58) and diastolic BP by 1.78 mm Hg (95% confidence interval, 0.73-2.82); these reductions were accompanied by 0.05 mmol/L (95% confidence interval, 0.03, 0.07) elevation of serum Mg compared with placebo.
   
   Who: normotensive and hypertensive adults in randomized double-blind placebo-controlled trials
   Effect: SBP -2.00 mm Hg (95% CI 0.43 to 3.58 reduction); DBP -1.78 mm Hg (95% CI 0.73 to 2.82 reduction); serum Mg +0.05 mmol/L
   Certainty: Residual heterogeneity acknowledged by the authors.
   Hypertension, 2016 · checked 2026-10-06 · we read the abstract
7. ev-mgbp-07 · Meta-analysis or systematic review · Cochrane systematic review and meta-analysis of randomized controlled trials · n = 545
   Combining all trials, participants receiving magnesium supplements as compared to control did not significantly reduce SBP (mean difference: -1.3 mmHg, 95% CI: -4.0 to 1.5, I(2)=67%), but did statistically significantly reduce DBP (mean difference: -2.2 mmHg, 95% CI: -3.4 to -0.9, I(2)=47%).
   
   Who: adults with systolic BP 140 mm Hg or higher or diastolic BP 85 mm Hg or higher, trials of 8 to 26 weeks
   Effect: SBP -1.3 mm Hg (95% CI -4.0 to 1.5), I2 67%; DBP -2.2 mm Hg (95% CI -3.4 to -0.9), I2 47%
   Certainty: 2006 review; authors judged the evidence weak and probably due to bias from poor-quality trials.
   Cochrane Database Syst Rev, 2006 · checked 2026-10-06 · we read the abstract
8. ev-mgbp-08 · Meta-analysis or systematic review · Cochrane systematic review and meta-analysis of randomized controlled trials · n = 545
   In view of the poor quality of included trials and the heterogeneity between trials, the evidence in favour of a causal association between magnesium supplementation and blood pressure reduction is weak and is probably due to bias.
   
   Who: 12 randomized controlled trials in adults with hypertension
   Effect: evidence for causal BP reduction judged weak, probably due to bias
   Certainty: Later, larger meta-analyses (2016, 2025) found small effects, but heterogeneity and bias concerns persist.
   Cochrane Database Syst Rev, 2006 · checked 2026-10-06 · we read the abstract
9. ev-mgbp-09 · Meta-analysis or systematic review · systematic review and dose-response meta-analysis of randomized controlled trials · n = 78 trials
   Mg supplementation was associated with significant improvements in several CMRFs, including body weight, lipid and glycemic profiles, blood pressure, and interleukin-6 levels.
   
   Who: adults in randomized controlled trials of magnesium supplementation, searched up to May 2026
   Effect: SBP WMD -2.50 mm Hg (95% CI -4.08 to -0.91); DBP WMD -1.58 mm Hg (95% CI -2.50 to -0.65)
   Certainty: Authors call the effects modest and clinical relevance uncertain; most trials used 300 mg/day or more.
   Nutrients, 2026 · checked 2026-10-06 · we read the abstract
10. ev-mgbp-10 · Meta-analysis or systematic review · meta-analysis of randomized controlled trials · n = 543
    Magnesium supplementation resulted in a mean reduction of 4.18 mm Hg in SBP and 2.27 mm Hg in DBP.
    
    Who: individuals with insulin resistance, prediabetes or noncommunicable chronic diseases; 365 to 450 mg/day elemental magnesium for 1 to 6 months
    Effect: SBP SMD -0.20 (95% CI -0.37 to -0.03), mean -4.18 mm Hg; DBP SMD -0.27 (95% CI -0.52 to -0.03), mean -2.27 mm Hg
    Certainty: Small trials; standardized effects are small.
    Am J Clin Nutr, 2017 · checked 2026-10-06 · we read the abstract
11. ev-mgbp-11 · Meta-analysis or systematic review · systematic review and meta-analysis of randomized controlled trials · n = 7 trials
    However, pooling seven RCTs together showed significant reduction of systolic blood pressure (WMD: - 5.78 mmHg, 95% CI: - 11.37 to - 0.19) and diastolic blood pressure (WMD: - 2.50 mmHg, 95% CI: - 4.58 to - 0.41) in T2DM patients.
    
    Who: patients with type 2 diabetes in randomized controlled trials
    Effect: SBP WMD -5.78 mm Hg (95% CI -11.37 to -0.19); DBP WMD -2.50 mm Hg (95% CI -4.58 to -0.41)
    Certainty: Only seven trials; lower CI bound near zero.
    Biol Trace Elem Res, 2021 · checked 2026-10-06 · we read the abstract
12. ev-mgbp-12 · Randomized controlled trial(s) · randomized double-blind placebo-controlled trial · n = not stated in abstract
    The magnesium group had a significant reduction in SBP (144 ± 17 vs. 134 ± 14 mmHg, P = 0.036) and DBP (88 ± 9 vs. 81 ± 8 mmHg, P = 0.005) at 6 months, without effect on plasma glucose, lipids, or arterial stiffness parameters.
    
    Who: hypertensive women aged 40 to 65 on hydrochlorothiazide with mean 24-h BP at least 130/80 mm Hg
    Effect: magnesium group SBP 144 to 134 mm Hg (P=0.036), DBP 88 to 81 mm Hg (P=0.005) at 6 months; within-group changes
    Certainty: Small single-center trial; reported within-group changes; 600 mg/day exceeds the 350 mg supplemental UL.
    J Hypertens, 2017 · checked 2026-10-06 · we read the abstract
13. ev-mgbp-13 · Randomized controlled trial(s) · multicentre double-blind randomized placebo-controlled trial · n = 200
    Magnesium supplementation in healthy first-time pregnant women is not to be recommended for prevention of blood pressure increase.
    
    Who: nulliparous healthy pregnant women
    Effect: no difference in blood pressure increase versus placebo
    Certainty: Dose not given in abstract; healthy low-risk pregnancies only.
    J Pregnancy, 2018 · checked 2026-10-06 · we read the abstract
14. ev-mgbp-14 · Observational data · systematic review and meta-analysis of observational studies · n = 58432
    The combination of 25 effect sizes from 22 studies showed an inverse relationship between circulating magnesium concentration and hypertension (OR = 0.65; 95% CI: 0.56-0.76) by comparing highest versus lowest levels of circulating magnesium concentration.
    
    Who: 3 cohort studies (15,730 subjects) and 19 cross-sectional studies (42,702 subjects)
    Effect: highest vs lowest circulating magnesium OR 0.65 (95% CI 0.56 to 0.76), I2 81.1%; per 0.5 mg/dL OR 0.93 (0.91 to 0.95)
    Certainty: Mostly cross-sectional; odds, not risk; cannot show cause.
    Nutr Rev, 2025 · checked 2026-10-06 · we read the abstract
15. ev-mgbp-15 · Position of an expert body · agency fact sheet · n = —
    Studies to date, however, have found that magnesium supplementation only marginally lowers blood pressure.
    
    Who: general population
    Effect: agency summary: marginal BP lowering
    Certainty: ODS cites the 2006 Cochrane review and the 2012 meta-analysis.
    NIH Office of Dietary Supplements, Magnesium fact sheet for health professionals · checked 2026-10-06 · we read the section
16. ev-mgbp-16 · Position of an expert body · agency fact sheet citing FDA qualified health claim · n = —
    In 2022, the U.S. Food and Drug Administration (FDA) approved a qualified health claim for conventional foods and dietary supplements that contain magnesium
    
    Who: foods and supplements with at least 84 mg magnesium per serving (supplements no more than 350 mg)
    Effect: qualified health claim (2022)
    Certainty: Qualified claims signal limited evidence, not an endorsement.
    NIH Office of Dietary Supplements, Magnesium fact sheet for health professionals · checked 2026-10-06 · we read the section
17. ev-mgbp-17 · Position of an expert body · agency fact sheet · n = —
    The Tolerable Upper Intake Level for supplemental magnesium is 350 mg for adults, and it ranges from 65 to 350 mg for children and adolescents, depending on age.
    
    Who: Adults; children and adolescents 65 to 350 mg depending on age
    Effect: UL for supplemental magnesium 350 mg/day (adults); food magnesium not counted
    Certainty: The blood pressure meta-analyses used a median of 365 to 368 mg, around the UL; some trials used 600 mg or more.
    NIH Office of Dietary Supplements, Magnesium fact sheet for health professionals · checked 2026-10-06 · we read the section
18. ev-mgbp-18 · Position of an expert body · agency fact sheet · n = —
    The risk of magnesium toxicity increases with impaired renal function or kidney failure because the ability to remove excess magnesium is reduced or lost
    
    Who: People with impaired renal function or kidney failure
    Effect: higher risk of magnesium toxicity
    Certainty: Relevant because chronic kidney disease and hypertension often coexist.
    NIH Office of Dietary Supplements, Magnesium fact sheet for health professionals · checked 2026-10-06 · we read the section
19. ev-mgbp-19 · Position of an expert body · agency fact sheet · n = —
    Magnesium may interact with certain medications, such as oral bisphosphonates, tetracyclines, and quinolone antibiotics.
    
    Who: people taking oral bisphosphonates, tetracyclines, quinolones, diuretics or proton pump inhibitors
    Effect: drug interactions; diuretics affect magnesium status
    Certainty: Diuretics are first-line blood pressure drugs, which links to the larger effect in medicated patients.
    NIH Office of Dietary Supplements, Magnesium fact sheet for health professionals · checked 2026-10-06 · we read the section