Does magnesium lower blood pressure?

What the reviews found

A 2025 review of magnesium and blood pressure pooled 38 randomized trials with 2,709 people. Each trial lasted at least 4 weeks, with a median of 12 weeks. Doses ranged from 82 to 637 mg of magnesium a day, with a median of 365 mg.^[1] Compared with placebo:

• All trials. Systolic pressure fell by 2.81 mmHg and diastolic by 2.05 mmHg.^[1]
• High blood pressure, on medicines. Systolic fell by 7.68 mmHg and diastolic by 2.96 mmHg.^[1]
• Low blood magnesium. Systolic fell by 5.97 mmHg and diastolic by 4.75 mmHg.^[1]
• Normal blood pressure. The change was not statistically significant.^[1]

The results varied a lot between trials, and higher doses did not give larger drops. The authors ask for larger trials that test higher doses.^[1]

A 2026 review of 78 trials found similar numbers: 2.50 mmHg lower systolic and 1.58 mmHg lower diastolic pressure. Its authors called the effects modest. Most trials in that review gave 300 mg a day or more, and two thirds lasted 12 weeks or longer.^[2] A 2016 review of 34 double-blind trials found 2.00 and 1.78 mmHg, with a median dose of 368 mg a day for a median of 3 months.^[3]

Older evidence was weaker

A 2006 Cochrane review of 12 trials in 545 people with high blood pressure found no clear change in systolic pressure and 2.2 mmHg lower diastolic pressure.^[4] Its authors judged the trials to be of poor quality, and the evidence weak and probably due to bias.^[4]

In 2022, the US Food and Drug Administration allowed a qualified health claim: diets with enough magnesium may lower the risk of high blood pressure. The claim also says that the FDA found the evidence inconsistent and inconclusive.^[5]

How big is the effect

For comparison, the DASH diet, with more fruit, vegetables and low-fat dairy and less fat, lowered blood pressure by 5.5 mmHg systolic and 3.0 mmHg diastolic.^[5] That diet also adds potassium and calcium, so the share due to magnesium is unknown.^[5]

Why it may work

Magnesium is a cofactor of enzyme systems that take part in blood pressure regulation.^[5]

How the trials gave it

In the 2016 review, 300 mg a day, or 1 month of use, was enough to raise blood magnesium and lower blood pressure.^[3] On average, the trials raised blood magnesium by 0.05 mmol/L.^[3]

Who should be careful

The 2025 review saw the largest drop in people who already took blood pressure medicines.^[1] Diuretics also change the body's magnesium level.^[5] People who take a medicine every day, or have kidney disease, should ask a doctor or pharmacist before taking magnesium.^[5]