Herbs and Supplements for High Blood Pressure: Effect Sizes from the Trials
The herbs and supplements with the best evidence for lowering blood pressure are aged garlic extract, hibiscus tea and beetroot juice, followed by omega-3, potassium and magnesium. In meta-analyses of randomised trials, garlic lowered systolic pressure by about 8 mmHg and diastolic by 5 to 6 mmHg in people with hypertension; hibiscus by about 7.6/3.5 mmHg; and beetroot juice by 4 to 8 mmHg systolic. For comparison, a single standard-dose blood-pressure drug lowers systolic pressure by around 9 mmHg, so the best of these are in the range of a low-dose medication, and the rest are worth 2 to 4 mmHg at most.
This guide is for adults with elevated or stage 1 blood pressure (120–139 systolic, 80–89 diastolic) who have been told to try lifestyle changes first, and for people on medication who want evidence-based add-ons rather than a replacement. If your reading is 140/90 or higher on repeated measurements, 180/120 or above at any time, or you have chest pain, breathlessness, severe headache or vision changes, you need a clinician, not a supplement. Blood pressure medication has decades of evidence for preventing strokes and heart attacks; nothing on this page does.
Measure before you start. Use a validated upper-arm cuff, take two readings morning and evening for 7 days, and average them. The effects here are small enough that without a baseline you will not know whether anything worked, and your clinician will need the numbers to adjust medication if you respond.
Quick answer
- Aged garlic extract — systolic down ~8 mmHg and diastolic ~5.5 mmHg in hypertensives across 12 trials
- Hibiscus tea — ~7.6/3.5 mmHg reduction in a meta-analysis of 5 RCTs; 3 cups a day for 6 weeks
- Beetroot juice — dietary nitrate lowered systolic pressure 4–8 mmHg; 250 mL/day for 4 weeks in hypertensives
- Omega-3 (EPA+DHA) — 2–3 g/day lowers pressure ~2/1.5 mmHg, around 4.5 mmHg in untreated hypertension
- Potassium — 4.5/2.6 mmHg lower in a 32-trial meta-analysis, biggest effect in people eating a lot of salt
- Magnesium — ~2/1.8 mmHg over 3 months at 368 mg/day; more in people who start deficient
The 10 best herbs and supplements for blood pressure
Ranked by the strength of human evidence. Strong = multiple trials or a meta-analysis. Moderate = a few small trials. Preliminary = early or animal data.
Garlic has the largest and most consistent effect on this list. A 2020 meta-analysis of 12 trials (553 hypertensive participants) found systolic pressure fell by 8.3 mmHg and diastolic by 5.5 mmHg versus placebo, an effect the authors compared to standard first-line medication. In the AGE at Heart trial, 1.2 g/day of aged garlic extract (1.2 mg S-allylcysteine) for 12 weeks lowered systolic pressure by 5 mmHg on average and by 11.5 mmHg in responders, with no interaction with existing drugs. People with normal pressure see little or no change.
- Key evidence
- 2020 meta-analysis of 12 RCTs in hypertension (Ried, Exp Ther Med); AGE at Heart RCT 2016
- Studied dose
- 1,200 mg/day of aged garlic extract (about 1.2 mg S-allylcysteine), or 600–900 mg/day of garlic powder, 8–12 weeks
- Best for
- Stage 1 hypertension, especially with raised cholesterol too
- Cautions
- Increases bleeding tendency with warfarin, aspirin, clopidogrel and NSAIDs; stop 7–10 days before surgery. May lower the effectiveness of some HIV protease inhibitors.
Hibiscus calyx tea acts like a mild ACE inhibitor and diuretic. In a 6-week Tufts trial, 3 cups a day lowered systolic pressure by 7.2 mmHg versus 1.3 mmHg for placebo tea in 65 pre- and mildly hypertensive adults, with the biggest drops (13.2 mmHg) in those starting above 129 systolic. A 2015 meta-analysis of 5 RCTs found an average reduction of 7.6 mmHg systolic and 3.5 mmHg diastolic. In small head-to-head trials it performed similarly to captopril 50 mg and lisinopril 10 mg, which should be read as encouraging rather than proof of equivalence.
- Key evidence
- 2015 meta-analysis of 5 RCTs (Serban et al., J Hypertens); McKay 2010 RCT, n=65
- Studied dose
- 3 cups/day of tea from 1.25 g dried calyx each (about 3.75 g/day), or 250 mg/day anthocyanin extract, 4–6 weeks
- Best for
- Elevated or stage 1 pressure in someone who would rather drink a tea than swallow a capsule
- Cautions
- Additive with ACE inhibitors, diuretics and other blood-pressure drugs, so monitor for dizziness. May lower the absorption of hydrochlorothiazide and reduce levels of some drugs cleared by the liver; avoid in pregnancy.
Beetroot is one of the richest sources of inorganic nitrate, which oral bacteria and the stomach convert into nitric oxide to relax arteries. A 2013 meta-analysis of 16 trials found systolic pressure fell by 4.4 mmHg with nitrate-rich juice. The best single trial gave 250 mL/day for 4 weeks to 64 patients with hypertension: clinic pressure fell 7.7/2.4 mmHg, 24-hour ambulatory pressure 7.7/5.2 mmHg, and arterial stiffness improved, all reversing within 2 weeks of stopping. The effect disappears if you use antibacterial mouthwash, which kills the bacteria needed to make nitrite.
- Key evidence
- 4-week double-blind RCT in 64 hypertensives (Kapil et al., Hypertension 2015); 2013 meta-analysis of 16 trials
- Studied dose
- 250–500 mL/day of beetroot juice (6–8 mmol nitrate), or one 70 mL concentrated shot, taken daily
- Best for
- People who want a food-based option and will stick to a daily juice; athletes with mildly raised pressure
- Cautions
- Can turn urine and stool pink (harmless). High in oxalate, so caution with a history of kidney stones; additive with nitrate drugs (GTN, isosorbide) and PDE5 inhibitors such as sildenafil.
Omega-3 (EPA and DHA)
Strong evidenceThis is one of the best-studied supplements for blood pressure, with a small effect. A 2022 dose-response meta-analysis of 71 trials (4,973 participants) found the sweet spot is 2 to 3 g/day of combined EPA and DHA, lowering systolic pressure by about 2 mmHg and diastolic by 1.5 mmHg overall, rising to around 4.5/3 mmHg in people with untreated hypertension and more in those with high triglycerides. Below 1 g/day there is essentially no effect, which is why ordinary 1-capsule fish-oil regimens disappoint.
- Key evidence
- 2022 dose-response meta-analysis of 71 RCTs (Zhang et al., J Am Heart Assoc)
- Studied dose
- 2–3 g/day of combined EPA+DHA from fish oil or algal oil, with a meal containing fat, 8–12 weeks
- Best for
- Hypertension with high triglycerides or an existing heart condition
- Cautions
- At 3 g/day or more it increases bleeding time; check with your prescriber if on warfarin, DOACs or antiplatelets, and stop a week before surgery. High-dose EPA has been linked to a small increase in atrial fibrillation in large trials.
Potassium
Strong evidencePotassium pushes the kidneys to excrete sodium and relaxes blood-vessel walls. A 2020 dose-response meta-analysis of 32 trials found supplementing to a total intake of about 90 mmol (3,500 mg) a day lowered systolic pressure by 4.5 mmHg and diastolic by 2.6 mmHg, with the largest effect in people eating a lot of salt and little potassium; above that intake the benefit flattened and then reversed. The WHO recommends at least 3,510 mg/day, and most people in the UK and US get under 2,500 mg, so food (potatoes, beans, bananas, spinach, yoghurt) should come first.
- Key evidence
- 2020 dose-response meta-analysis of 32 RCTs (Filippini et al., J Am Heart Assoc); WHO guideline 2012
- Studied dose
- Aim for 3,500 mg/day total from food; supplements are limited to 99 mg per tablet in the US, so use potassium-enriched salt substitutes instead if your kidneys are healthy
- Best for
- People with a high-salt diet and normal kidney function who are not on potassium-sparing drugs
- Cautions
- Dangerous with kidney disease, ACE inhibitors, ARBs, spironolactone, eplerenone or amiloride, where it can cause life-threatening hyperkalaemia; check a blood potassium before using a salt substitute if you take any of these.
Magnesium
Moderate evidenceMagnesium is a natural calcium-channel blocker, and low intake is common. A 2016 meta-analysis of 34 double-blind trials (2,028 participants) found a median dose of 368 mg/day for 3 months lowered systolic pressure by 2.0 mmHg and diastolic by 1.8 mmHg, with larger drops in people who started with low magnesium or insulin resistance. It is not a stand-alone treatment, but it is cheap and safe, and it improves the sleep problems and cramps that often sit alongside hypertension.
- Key evidence
- 2016 meta-analysis of 34 RCTs (Zhang et al., Hypertension)
- Studied dose
- 300–400 mg/day of elemental magnesium as glycinate, citrate or taurate, with food, for at least 12 weeks
- Best for
- Hypertension with insulin resistance, migraines, cramps or poor sleep
- Cautions
- Reduce the dose with kidney disease. Separate from levothyroxine, quinolone and tetracycline antibiotics and bisphosphonates by 2 hours; combined with other blood-pressure drugs it can cause light-headedness.
Oleuropein, the main polyphenol in olive leaf, relaxes arteries and inhibits ACE in the lab. In an 8-week double-blind trial of 232 patients with stage 1 hypertension, 500 mg of extract twice daily (standardised to 16–24% oleuropein) lowered systolic pressure by 11.5 mmHg and diastolic by 4.8 mmHg, not significantly different from captopril 12.5–25 mg twice daily. A 6-week UK crossover trial in 60 prehypertensive men found a more modest 3.95/3.0 mmHg reduction at 136 mg oleuropein daily. Two decent trials, both positive, but not yet a meta-analysis.
- Key evidence
- 8-week RCT vs captopril, n=232 (Susalit et al., Phytomedicine 2011); Lockyer 2017 crossover RCT, n=60
- Studied dose
- 500 mg of leaf extract standardised to 16–24% oleuropein twice daily, 6–8 weeks
- Best for
- Stage 1 hypertension with raised LDL or glucose, as it modestly improves both
- Cautions
- Additive with blood-pressure and diabetes medication; may increase bleeding tendency. No data in pregnancy or breastfeeding.
Hawthorn is better established for mild heart failure than for blood pressure. The best pressure trial gave 1,200 mg/day of a leaf-and-flower extract to 79 patients with type 2 diabetes already on medication for 16 weeks: diastolic pressure fell 2.6 mmHg more than placebo, with no significant change in systolic. An earlier 10-week pilot at 500 mg/day showed a trend toward lower diastolic pressure. It is gentle, well tolerated and works slowly, which makes it an add-on rather than a lead.
- Key evidence
- 16-week RCT in 79 diabetic patients (Walker et al., Br J Gen Pract 2006)
- Studied dose
- 500–1,200 mg/day of a leaf-and-flower extract standardised to 2–3% flavonoids or 18–20% OPCs, 12–16 weeks
- Best for
- Mild hypertension in someone with early heart failure, angina or palpitations, under medical supervision
- Cautions
- May potentiate digoxin, nitrates, beta-blockers and PDE5 inhibitors; can cause dizziness. Do not self-treat heart failure or chest pain with it, and tell your cardiologist you are taking it.
Green tea's catechins improve endothelial function, and regular drinkers have lower rates of stroke in cohort studies. The randomised evidence is modest: a 2014 meta-analysis of 13 trials found green tea or its extract lowered systolic pressure by 2.0 mmHg and diastolic by 1.9 mmHg, with slightly larger effects in trials longer than 12 weeks and in people with higher starting pressure. The caffeine in whole tea can raise pressure acutely, which partly cancels the catechin benefit in some people.
- Key evidence
- 2014 meta-analysis of 13 RCTs (Khalesi et al., Eur J Nutr)
- Studied dose
- 3–4 cups/day of brewed green tea, or 300–500 mg/day of a decaffeinated extract providing 200–300 mg EGCG, 12 weeks
- Best for
- People who already drink tea and want to swap black for green; those with raised LDL as well
- Cautions
- Extracts taken on an empty stomach above about 800 mg EGCG/day have caused liver injury; take with food and keep the dose moderate. Reduces absorption of iron and the beta-blocker nadolol, and the caffeine interacts with stimulants and some anxiety medications.
Nattokinase
Preliminary evidenceNattokinase is an enzyme from fermented soybeans with blood-thinning and mild ACE-inhibiting activity. In an 8-week double-blind trial of 86 Korean adults with pre- or stage 1 hypertension, 2,000 fibrinolytic units a day lowered systolic pressure by 5.5 mmHg and diastolic by 2.8 mmHg more than placebo. A 2016 North American trial at a higher dose found a diastolic reduction of about 3 mmHg but no systolic change overall, with a larger effect in men. Two small trials with mixed results is why it sits at the bottom.
- Key evidence
- 8-week RCT, n=86 (Kim et al., Hypertens Res 2008); 2016 RCT in North American adults
- Studied dose
- 2,000 FU (about 100 mg) once daily on an empty stomach, 8 weeks
- Best for
- People with mildly raised pressure who also have a reason to want gentler clotting, under medical advice
- Cautions
- Significant bleeding risk with warfarin, DOACs, aspirin and clopidogrel; stop 2 weeks before surgery or dental work. Natto itself is high in vitamin K, but the purified enzyme is not; avoid in pregnancy.
How to choose
- If you want the single biggest effect, start with aged garlic extract 1.2 g/day, measure for 8 weeks, and keep it only if your average falls.
- If you prefer food to capsules, hibiscus tea (3 cups) plus a daily beetroot shot is the most evidence-backed food combination and together may be worth 8–12 mmHg systolic.
- If you eat a lot of salt and little fruit and vegetables, fixing potassium intake and cutting sodium will beat any herb here; use a potassium-enriched salt substitute if your kidneys and medications allow it.
- If you also have high triglycerides or heart disease, choose omega-3 at 2–3 g/day, which addresses both.
- If you have insulin resistance, poor sleep or cramps alongside hypertension, add magnesium; if you have early heart failure, hawthorn under supervision.
- L-arginine (4–24 g/day) lowered pressure about 5/2.7 mmHg in a 2011 meta-analysis of 11 trials, and citrulline shows similar hints, but doses are large, trials are short and we rank both below the picks above; ask AskMN if you want the trial-by-trial detail.
What to skip
Coenzyme Q10 for blood pressure
The 2016 Cochrane review found that once poor-quality trials were excluded, CoQ10 did not significantly lower systolic or diastolic pressure (two trials, 50 participants, about 3.7 mmHg systolic with wide uncertainty). It has better evidence for statin muscle symptoms and heart failure than for hypertension.
'Nitric oxide booster' pre-workout blends
They borrow the beetroot and arginine story but typically contain 1–3 g of arginine or citrulline, a fraction of the 6 g or more used in trials, alongside 200–300 mg of caffeine, which raises blood pressure acutely. Net effect for a hypertensive person is often upward.
Apple cider vinegar
The evidence is a handful of rat studies and no randomised trial showing a blood-pressure reduction in humans. It can also erode tooth enamel and lower potassium at high intakes.
Liquorice-containing 'adrenal' or 'energy' herbal blends
Glycyrrhizin raises blood pressure by mimicking aldosterone; as little as 50–100 g of liquorice a day for 2 weeks has caused hypertension and dangerously low potassium. If you have high blood pressure, check herbal tea and supplement labels for liquorice root.
Safety and when to see a clinician
- Do not stop or reduce blood-pressure medication because a supplement lowered your readings. Take your 7-day averages to your prescriber; adding a supplement and lowering a drug dose is their call.
- Bleeding: garlic, omega-3 at 3 g/day or more, nattokinase, hawthorn and olive leaf all increase bleeding tendency. Talk to your clinician before combining them with warfarin, apixaban, rivaroxaban, aspirin or clopidogrel, and stop them 1–2 weeks before surgery.
- Potassium can be fatal in the wrong person. Do not use potassium supplements or salt substitutes if you have kidney disease or take ACE inhibitors, ARBs, spironolactone, eplerenone, amiloride or trimethoprim without a blood test first.
- Stacking several of these with existing medication can drop pressure too far, causing dizziness, falls and fainting, especially in older adults. Introduce one thing at a time and stand up slowly.
- Pregnancy: hibiscus, nattokinase, olive leaf and high-dose garlic lack safety data or have signals of harm. High blood pressure in pregnancy (pre-eclampsia) is an emergency and needs obstetric care, not herbs.
- See a clinician urgently with a reading of 180/120 or above, or any reading with chest pain, breathlessness, sudden severe headache, confusion, weakness on one side or vision loss.
What matters as much as any herb
- The DASH diet lowers systolic pressure by about 11 mmHg in people with hypertension, more than any supplement on this page; it is high in vegetables, fruit, beans, nuts and low-fat dairy and low in salt and processed meat.
- Cutting sodium to under 2,300 mg/day (1 teaspoon of salt in total) lowers systolic pressure by 5–6 mmHg in hypertensives; most of the salt in a typical diet comes from bread, processed meat, sauces and restaurant food rather than the salt shaker.
- Losing weight lowers pressure by roughly 1 mmHg per kilogram; a 5 kg loss is worth a low-dose drug.
- Aerobic exercise 90–150 minutes a week lowers systolic pressure by 5–8 mmHg; isometric handgrip training for 12 minutes, 3 days a week, achieved around 7 mmHg in a 2023 meta-analysis.
- Alcohol above 1 drink a day raises blood pressure; cutting from 3–4 drinks to 1 lowers systolic pressure by about 5 mmHg.
Frequently asked questions
What is the best herb to lower blood pressure fast?
Nothing here is fast or for emergencies. Beetroot juice acts within 3 to 6 hours of a single serving and is the closest thing to a quick effect, lowering systolic pressure by around 4–5 mmHg for the rest of the day. Garlic and hibiscus take 4 to 8 weeks to show their full effect.
Can hibiscus tea replace blood pressure medication?
No. Two small trials found hibiscus comparable to low doses of captopril or lisinopril over 4 weeks, but those drugs were chosen for their proven ability to prevent strokes and heart attacks over years, which hibiscus has never been tested for. It is a reasonable add-on for stage 1 hypertension and a reasonable first step while you fix diet and weight.
How much does garlic lower blood pressure?
In people with hypertension, about 8 mmHg systolic and 5–6 mmHg diastolic on average over 8 to 12 weeks, with about 30–40% of people responding strongly and the rest barely at all. Aged garlic extract at 1.2 g/day is the best-studied form; raw cloves and cooked garlic are far less predictable.
Does magnesium lower blood pressure?
Slightly: about 2 mmHg systolic and diastolic over 3 months at around 370 mg/day in the pooled trials. People who start deficient, or who have insulin resistance, tend to get more. It is worth taking for its other benefits if you fit that picture, but it will not control hypertension on its own.
Which supplements should I avoid with blood pressure medication?
Liquorice (raises pressure), potassium supplements and salt substitutes with ACE inhibitors, ARBs or spironolactone (dangerous hyperkalaemia), high-dose caffeine and stimulant 'fat burners', and decongestants containing pseudoephedrine. Garlic, omega-3 and nattokinase need caution with blood thinners rather than pressure drugs.
Does beetroot juice really work for blood pressure?
Yes, with two conditions: you need a nitrate dose of at least 6 mmol (about 250 mL of juice or one 70 mL concentrated shot) and you must not use antibacterial mouthwash, which kills the oral bacteria that convert nitrate to nitrite. Under those conditions the 4-week trial in hypertensives showed a 7.7 mmHg systolic reduction.
Is omega-3 or fish oil good for high blood pressure?
At 2–3 g/day of EPA plus DHA it lowers pressure by about 2/1.5 mmHg, and about 4.5/3 mmHg if you have untreated hypertension. The typical one-capsule dose of 300 mg does nothing measurable. It is most worth taking if your triglycerides are also high.
References
- Ried K. Garlic lowers blood pressure in hypertensive subjects, improves arterial stiffness and gut microbiota: a review and meta-analysis. Experimental and Therapeutic Medicine (2020)
- McKay DL, Chen CY, Saltzman E, Blumberg JB. Hibiscus sabdariffa L. tea (tisane) lowers blood pressure in prehypertensive and mildly hypertensive adults. Journal of Nutrition (2010)
- Serban C, Sahebkar A, Ursoniu S, et al.. Effect of sour tea (Hibiscus sabdariffa L.) on arterial hypertension: a systematic review and meta-analysis of randomized controlled trials. Journal of Hypertension (2015)
- Kapil V, Khambata RS, Robertson A, et al.. Dietary nitrate provides sustained blood pressure lowering in hypertensive patients: a randomized, phase 2, double-blind, placebo-controlled study. Hypertension (2015)
- Siervo M, Lara J, Ogbonmwan I, Mathers JC. Inorganic nitrate and beetroot juice supplementation reduces blood pressure in adults: a systematic review and meta-analysis. Journal of Nutrition (2013)
- Zhang X, Ritonja JA, Zhou N, et al.. Omega-3 polyunsaturated fatty acids intake and blood pressure: a dose-response meta-analysis of randomized controlled trials. Journal of the American Heart Association (2022)
- Zhang X, Li Y, Del Gobbo LC, et al.. Effects of magnesium supplementation on blood pressure: a meta-analysis of randomized double-blind placebo-controlled trials. Hypertension (2016)
- Filippini T, Naska A, Kasdagli MI, et al.. Potassium intake and blood pressure: a dose-response meta-analysis of randomized controlled trials. Journal of the American Heart Association (2020)
- Susalit E, Agus N, Effendi I, et al.. Olive (Olea europaea) leaf extract effective in patients with stage-1 hypertension: comparison with Captopril. Phytomedicine (2011)
- Walker AF, Marakis G, Simpson E, et al.. Hypotensive effects of hawthorn for patients with diabetes taking prescription drugs: a randomised controlled trial. British Journal of General Practice (2006)
- Ho MJ, Li EC, Wright JM. Blood pressure lowering efficacy of coenzyme Q10 for primary hypertension. Cochrane Database of Systematic Reviews (2016)
- Kim JY, Gum SN, Paik JK, et al.. Effects of nattokinase on blood pressure: a randomized, controlled trial. Hypertension Research (2008)
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Ask about blood pressureThis guide is educational and is not medical advice. Herbs and supplements can interact with prescription medicines and are not regulated like drugs. Talk with a clinician or pharmacist before starting anything new, especially if you are pregnant, breastfeeding, have a chronic condition, or take medication.