Several herbs have measurable effects on blood pressure, with garlic, hibiscus, celery seed, and ginger holding the strongest evidence from clinical trials. Garlic supplements stand out with the most consistent data: a meta-analysis of 12 trials found they lower systolic blood pressure by an average of 8.3 mmHg and diastolic by 5.5 mmHg in people with hypertension. That’s a meaningful drop, comparable to some first-line medications. But the details matter, including how much to take, which form works, and whether these herbs play well with prescription drugs.
Garlic
Garlic is the most studied herb for blood pressure, and the results are genuinely impressive. Across 553 hypertensive participants in 12 clinical trials, garlic supplements lowered the top number (systolic) by about 8 mmHg and the bottom number (diastolic) by about 5.5 mmHg on average. One dose-response trial found that aged garlic extract achieved a 10 mmHg systolic reduction within two to three months.
Raw garlic cloves aren’t the form tested in most research. The trials used aged garlic extract in capsule form, which concentrates the active compounds while reducing the harshness on your stomach. If you’re buying a supplement, look for aged garlic extract specifically. The effective dose in the strongest trial was two capsules daily, though products vary in concentration. Fresh garlic in cooking contributes some benefit, but the amounts used in meals are far smaller than what the trials tested.
Hibiscus Tea
Hibiscus tea is one of the simplest options to try. A USDA-backed trial had participants drink three cups of hibiscus tea daily for six weeks and saw significant blood pressure reductions compared to a placebo group. The tea is made from dried hibiscus flowers (the deep red, tart variety sometimes called “sour tea” or “agua de jamaica”), steeped in hot water for several minutes.
Three cups a day is the amount supported by research. You can drink it hot or iced. Hibiscus has a tangy, cranberry-like flavor that most people find pleasant without added sugar, though a small amount of honey won’t undermine the effect. Commercially available hibiscus tea bags work fine, as long as hibiscus is the primary ingredient and not buried behind other herbs.
Celery Seed
Celery seed extract has shown significant reductions in both systolic and diastolic blood pressure across a meta-analysis of ten trials involving 511 participants. Most of the successful trials used celery seed extract capsules at around 1,340 mg daily for about four weeks, though study durations ranged from 12 to 84 days.
The active compound in celery seed relaxes the smooth muscle lining your blood vessels, which allows them to widen. Eating celery stalks provides some of the same compounds but in much lower concentrations. If you’re looking for a measurable effect, the extract in capsule form is more reliable than adding extra celery to your salads.
Ginger
Ginger lowers blood pressure through two distinct pathways. It stimulates receptors in your nervous system that signal blood vessels to relax, and it also blocks calcium from entering the muscle cells of artery walls. That second mechanism is the same basic approach used by a major class of prescription blood pressure drugs (calcium channel blockers). When calcium can’t flow into those cells as easily, the vessels stay more relaxed and pressure drops.
Most of the research has used ginger extract rather than the fresh root you’d grate into a stir-fry. Fresh ginger in cooking and ginger tea likely contribute some benefit, but the concentrations tested in studies are higher than what you’d get from food alone. Ginger supplements are widely available, though standardized dosing across products varies quite a bit.
Holy Basil (Tulsi)
Holy basil, known as tulsi in traditional Indian medicine, contains a compound called eugenol that relaxes blood vessels in a dose-dependent way, meaning more of it produces a stronger effect. Research has shown reductions in both systolic and diastolic pressure, though most of the evidence comes from animal studies rather than large human trials. Tulsi tea is the most common way people consume it, and it’s widely available in health food stores. It has a peppery, slightly sweet flavor distinct from the Italian basil you’d put on pizza.
Hawthorn
Hawthorn berry extract has a long history in European herbal medicine for heart health. It widens blood vessels and may strengthen the heart’s pumping efficiency. However, hawthorn carries notable interaction risks with prescription heart medications, including beta blockers, calcium channel blockers, and nitrates. If you’re already on blood pressure medication, hawthorn is one of the riskier herbs to add without medical guidance.
Herbs That Can Backfire
Not every “natural” option is safe or helpful for blood pressure. A few popular herbs and supplements actually raise blood pressure or interfere with medications designed to lower it.
- Licorice root can reduce the effectiveness of blood pressure drugs and diuretics. Even licorice candy made with real licorice extract (not the artificially flavored kind) can push blood pressure up with regular consumption.
- St. John’s wort weakens the effect of calcium channel blockers, one of the most commonly prescribed classes of blood pressure medication. It also interferes with statins and blood thinners.
- Ginseng has unclear interactions with calcium channel blockers and other blood pressure drugs. The research has produced mixed results, making it unpredictable when combined with prescriptions.
Combining Herbs With Medication
The biggest practical risk with blood pressure herbs isn’t that they don’t work. It’s that they work through the same mechanisms as prescription drugs, and stacking them can drop your pressure too low. Danshen, for example, combined with a calcium channel blocker can cause dangerously low blood pressure. Hawthorn layered on top of a beta blocker amplifies the drug’s effect in ways that aren’t predictable from the supplement label alone.
If you’re on any prescription blood pressure medication, keep a written list of every supplement you take and share it at medical appointments. Herbs that are perfectly safe on their own can become problematic when paired with the wrong drug. This is especially true for garlic and ginger, which both affect how blood vessels respond to calcium, the same pathway targeted by a common class of prescriptions.
What Realistic Results Look Like
The herbs with the best evidence, garlic, hibiscus, and celery seed, typically produce drops in the range of 5 to 10 mmHg systolic. For someone with mildly elevated blood pressure (say, 135/85), that could be enough to bring readings back into a normal range. For someone at 160/100, herbs alone won’t close the gap.
Timing matters too. Most trials show results appearing after two to six weeks of consistent daily use. A single cup of hibiscus tea or one garlic capsule won’t produce a noticeable change. The effect builds with regular use and fades when you stop. These herbs work best as one layer in a broader approach that includes reducing sodium, staying physically active, managing stress, and maintaining a healthy weight. Each of those changes contributes its own 5 to 10 mmHg reduction, and the effects stack.