Cloves contain eugenol, a compound that relaxes blood vessels and lowers blood pressure in animal studies. While the spice shows genuine promise for heart health, the evidence in humans is still limited, and cloves alone are not a replacement for blood pressure medication. That said, adding them to your diet in moderate amounts is safe for most people and may offer a small benefit as part of a broader approach to managing blood pressure.
How Cloves Affect Blood Pressure
Eugenol, the main active compound in cloves (making up roughly 60 to 90 percent of clove oil), works by relaxing the smooth muscle in your blood vessel walls. It does this primarily by blocking calcium channels, the tiny gateways that allow calcium to flow into muscle cells and trigger contraction. When those channels are blocked, blood vessels widen, resistance drops, and blood pressure falls. This is actually the same basic mechanism used by a common class of prescription blood pressure drugs called calcium channel blockers.
In rats, injections of eugenol produced immediate, dose-dependent drops in both blood pressure and heart rate. The blood pressure reduction came from active relaxation of blood vessels rather than changes in nervous system signaling. Eugenol also activates a specific receptor (called TRPV4) on the cells lining blood vessel walls, which triggers dilation in arteries supplying the gut and brain. These effects have been consistently reproduced across multiple animal studies, which gives researchers confidence that the mechanism is real.
What the Human Evidence Shows
Direct human trials on clove (Syzygium aromaticum) and blood pressure are scarce. Most of the clinical research has focused on eugenol’s effects in lab settings or animal models. The human studies that do exist tend to be small or use eugenol as part of a broader herbal intervention, making it hard to isolate clove’s specific contribution.
No large, well-designed clinical trial has tested clove supplementation alone for hypertension in humans. This is an important gap. Animal results don’t always translate to people, especially because the doses used in rat studies (1 to 10 mg/kg of eugenol injected intravenously) deliver the compound directly into the bloodstream, bypassing digestion entirely. When you eat cloves or drink clove tea, your body absorbs eugenol less efficiently, and the dose reaching your blood vessels is much lower.
That doesn’t mean cloves are useless for blood pressure. It means the effect in real-world use is likely modest, not dramatic. Think of cloves as one small, supportive piece of a heart-healthy lifestyle rather than a stand-alone treatment.
How to Use Cloves Safely
The simplest way to incorporate cloves is as a cooking spice. One teaspoon of ground cloves provides about 0.63 mg of manganese (a mineral involved in bone health and metabolism) along with small amounts of vitamin K and fiber. Used this way, in meals, teas, or smoothies, the amounts are well within safe limits.
Clove tea is a popular preparation: steep 3 to 5 whole cloves in hot water for 10 to 15 minutes. This extracts some eugenol into the water, though less than you’d get from clove oil. The tea is mild, warm, and slightly sweet, and drinking one or two cups a day is generally considered safe.
Clove oil is far more concentrated. Research in rats found that doses above 20 mg per kilogram of body weight caused structural and functional liver damage, while 10 mg per kilogram appeared safe for long-term use. For a 70 kg (154-pound) person, that safe threshold would translate to roughly 700 mg of eugenol per day, but human metabolism differs from rats, and a conservative approach makes sense. Swallowing undiluted clove oil is not recommended. If you use clove oil supplements, stick to the dosage on the label and choose products from reputable brands that list eugenol content.
Risks and Drug Interactions
Eugenol inhibits platelet activity, meaning it can slow blood clotting. If you take blood thinners like warfarin, aspirin, or other anticoagulant medications, regular use of clove supplements or clove oil could increase your risk of bleeding. This interaction is well documented enough that pharmacology references flag it specifically. Signs to watch for include unusual bruising, prolonged bleeding from minor cuts, blood in urine or stool, and heavier than normal menstrual bleeding.
If you’re already on blood pressure medication, adding concentrated clove supplements could theoretically amplify the blood-pressure-lowering effect, potentially dropping your pressure too low. This is less of a concern with culinary amounts of ground cloves or the occasional cup of clove tea, but it matters if you’re considering high-dose capsules or oils.
People with liver conditions should be cautious with concentrated clove products, given the animal evidence of liver damage at higher doses.
Cloves Compared to Proven Approaches
To put cloves in perspective, the lifestyle changes with the strongest evidence for lowering blood pressure include reducing sodium intake (which can drop systolic pressure by 5 to 6 mmHg), regular aerobic exercise (5 to 8 mmHg reduction), losing excess weight (roughly 1 mmHg per kilogram lost), and following a diet rich in fruits, vegetables, and whole grains. These interventions have been tested in large human trials and produce reliable, measurable results.
Cloves, by contrast, have solid biological plausibility but lack that same level of human proof. They fit best as a flavorful addition to an already heart-healthy diet. Replacing salt with cloves and other spices when seasoning food, for example, gives you two potential benefits at once: less sodium and a small dose of eugenol.
If your blood pressure is consistently above 130/80 mmHg, dietary spices alone are unlikely to bring it into a healthy range. But as part of a package that includes exercise, weight management, stress reduction, and a good diet, cloves are a reasonable and enjoyable inclusion.