Several supplements have credible evidence for modestly lowering blood pressure, though none replace medication for people with clinical hypertension. The strongest data supports magnesium, omega-3 fatty acids, potassium, and aged garlic extract, with typical reductions ranging from 2 to 10 mmHg on the systolic (top number) side depending on your starting blood pressure and whether you’re already on medication. Here’s what the research actually shows for each one.
Magnesium
Magnesium is one of the most studied supplements for blood pressure, and a large meta-analysis of randomized controlled trials published in the AHA journal Hypertension found that supplementation lowered systolic blood pressure by about 2.8 mmHg and diastolic by about 2 mmHg compared to placebo. The median dose across studies was 365 mg of elemental magnesium daily, taken for a median of 12 weeks.
The more interesting finding is who benefits most. People already taking blood pressure medication who added magnesium saw systolic drops of nearly 7.7 mmHg, a clinically meaningful improvement. And people who were low in magnesium at the start saw reductions of about 6 mmHg systolic and nearly 5 mmHg diastolic. If your magnesium levels are normal and you’re not on medication, the effect was much smaller and not always statistically significant.
This makes magnesium a reasonable add-on for people already managing hypertension, especially if blood work shows low magnesium levels. Common supplemental forms include magnesium glycinate, citrate, and oxide, which differ mainly in how well your gut absorbs them and whether they cause digestive side effects.
Omega-3 Fatty Acids
Fish oil supplements containing EPA and DHA lower blood pressure in a dose-dependent way, but you need more than most people take. A dose-response meta-analysis in the Journal of the American Heart Association found the optimal daily intake is about 3 grams of combined omega-3s. At that dose, systolic blood pressure dropped by roughly 2.6 mmHg and diastolic by about 1.8 mmHg. The relationship between dose and benefit is nonlinear: going from 1 gram to 3 grams makes a real difference, but going higher than 3 grams doesn’t add much.
Most standard fish oil capsules contain around 300 mg of combined EPA and DHA per capsule, meaning you’d need about 10 capsules a day to hit the effective dose. Concentrated fish oil products contain 1,000 mg or more per capsule, making the math more realistic. If you eat fatty fish like salmon or mackerel several times a week, you’re already covering some of that intake through food.
Potassium
The 2025 AHA/ACC blood pressure guidelines strongly recommend increasing potassium intake to 3,500 to 5,000 mg per day to help prevent and treat elevated blood pressure. The guidelines suggest getting potassium from food first, with moderate-dose supplementation as an alternative. Potassium works by helping your kidneys excrete sodium and by relaxing blood vessel walls.
Most Americans get only about 2,500 mg of potassium daily, well below the recommended range. Foods like bananas, potatoes, spinach, beans, and avocados are rich sources. Supplemental potassium is available over the counter, but doses are typically capped at 99 mg per tablet because high-dose potassium supplements can be dangerous for people with kidney problems or those taking certain blood pressure medications that already raise potassium levels.
Aged Garlic Extract
Aged garlic extract has some of the most impressive numbers among herbal supplements. In a randomized, double-blind trial, patients with uncontrolled hypertension (systolic blood pressure at or above 140 mmHg despite medication) who took 960 mg of aged garlic extract daily for 12 weeks saw their systolic pressure drop by an average of 10.2 mmHg compared to controls. That’s a substantial reduction, comparable to adding a second medication.
The key distinction is “aged” garlic extract, which contains a stable compound called S-allylcysteine that fresh garlic and standard garlic supplements don’t provide in meaningful amounts. Raw garlic cloves or basic garlic capsules haven’t shown the same consistency in trials. If you’re exploring this option, look for products standardized to their S-allylcysteine content.
Hibiscus Tea
Hibiscus isn’t a capsule supplement in the traditional sense, but drinking hibiscus tea three times daily has shown real effects. In a randomized, placebo-controlled trial of adults with mildly elevated blood pressure, three cups a day for six weeks lowered systolic blood pressure by 7.2 mmHg compared to just 1.3 mmHg for the placebo beverage. Participants were not taking blood pressure medication, so this reflects the effect in people with early-stage or borderline hypertension.
Hibiscus tea is widely available, inexpensive, and generally well tolerated. It has a tart, cranberry-like flavor. If you dislike the taste, hibiscus extract capsules exist, though the clinical data is strongest for the brewed tea itself.
Supplements With Weak or No Evidence
CoQ10
Coenzyme Q10 is frequently marketed for heart health, but the evidence for blood pressure is thin. A Cochrane review found that CoQ10 did not significantly change either systolic or diastolic blood pressure in the available randomized trials. The pooled data showed a nonsignificant drop of about 3.7 mmHg systolic, but with wide confidence intervals that crossed zero, meaning the effect could easily be due to chance.
Vitamin D
Despite the logical appeal of linking vitamin D deficiency to cardiovascular risk, supplementation doesn’t lower blood pressure. A CDC-published meta-analysis found essentially zero effect on systolic blood pressure (a change of 0.00 mmHg) and no meaningful change in diastolic pressure. This held true even in people who started with low vitamin D levels. Vitamin D has legitimate uses, but blood pressure control isn’t one of them.
L-Arginine
L-arginine is the raw material your body uses to produce nitric oxide, a molecule that relaxes blood vessels. In theory, more L-arginine should mean more nitric oxide and lower blood pressure. In practice, your cells already have far more L-arginine than the enzyme that converts it can use, so adding more through supplements doesn’t reliably boost nitric oxide production in healthy people. Some small studies show modest effects, but no large meta-analysis supports L-arginine as a reliable blood pressure supplement.
Supplements That Can Raise Blood Pressure
Some supplements marketed for energy, weight loss, or general wellness can actually increase blood pressure or interfere with blood pressure medications. The Mayo Clinic flags several to be cautious with: ephedra (also called ma-huang), licorice root, ginseng, guarana, and arnica. Ephedra and guarana are stimulants that directly constrict blood vessels. Licorice root causes your body to retain sodium and lose potassium, both of which push blood pressure up. If you’re managing hypertension, check the ingredient labels of any supplement you take for these ingredients.
How Long Before You See Results
Most blood pressure supplement trials run for 6 to 12 weeks before measuring outcomes, and that’s a reasonable expectation for how long consistent daily use takes to produce measurable changes. Dietary changes like reducing sodium can show up within a couple of weeks, while supplements generally take longer because the effects are more gradual. If you’re tracking your blood pressure at home, give any new supplement at least 8 weeks of consistent use before judging whether it’s working. Take readings at the same time of day, seated, after five minutes of rest, to get reliable comparisons.
The supplements with the best evidence, magnesium, omega-3s, potassium, and aged garlic extract, produce modest reductions on their own. Their real value often comes from stacking them alongside dietary changes like reducing sodium, increasing fruit and vegetable intake, and regular physical activity. These lifestyle shifts collectively add up to blood pressure reductions that rival a single medication for people with mild to moderate hypertension.