Cloves are the dried, unopened flower buds of an evergreen tree, Syzygium aromaticum, native to the Maluku (Molucca) islands of Indonesia. In a 2010 ranking of 452 foods and drinks built from the Phenol-Explorer database, cloves came out on top for total polyphenols, at 15,000 mg per 100 g. A teaspoon weighs only 2.1 g, so it holds roughly 300 mg, and people eat cloves by the pinch.
Much of the flavor and most of the research come from one compound, eugenol, the main component of clove oil. In lab tests eugenol switches on a warmth-sensing channel in cells from the tongue, which fits the warm feel of cloves. It also numbs, which made clove oil a dentist’s tool, and the oil, unlike the spice, is dangerous for small children.
A teaspoon of ground cloves has only 6 calories and 0.7 g of fiber, yet it supplies 1.26 mg of manganese, 55% of the daily value. Among the 23 herbs and spices on this site, none has more manganese per teaspoon. The studies below mostly test extracts, oil, gels and mouthwashes, so they say little about what a pinch in a stew does.
Health benefits of cloves
The top findings from 12 studies, strongest evidence first
What the stars mean
- Strong. Several randomized trials, pooled in a meta-analysis, point the same way, or regulators (FDA or EFSA) have approved the claim.
- Moderate. Good randomized trials support it, but there are fewer of them, or their results vary.
- Limited. Small, short or single trials, or mixed results. Promising, but it needs confirmation.
Population and lab studies get no stars: they show a link or a mechanism, not proof.
How we rate evidence →- ★Lower triglycerides after a fatty mealA nine-spice blend that included cloves lowered triglycerides by 31% after a fatty meal in 20 overweight adults, but only when they rested afterward. It cannot show what cloves did on their own.
- ★Lower blood sugar after meals, as a capsuleIn 13 adults, a clove extract capsule for 30 days lowered blood sugar after meals by about 13 to 17 mg/dL. There was no placebo group, and it was an extract, not the kitchen spice.
- ★Less severe hangovers in 16 menA clove bud extract capsule taken with alcohol cut hangover severity by 55%, with lower markers of inflammation. The authors work for the company that makes the extract.
- ★Clove gel numbed needle pricks in the mouthIn 73 adults, a clove gel on the mouth lining numbed needle pricks about as well as 20% benzocaine gel. It was applied, not eaten, and tested pricks in healthy people, not toothache.
- ★Less pneumonia with a clove mouthwashIn 168 intensive care patients, a clove mouthwash twice a day for 5 days gave less ventilator-associated pneumonia: 20.2% against 41.7% with chlorhexidine. It was a rinse, not food, and one trial at one hospital.
All 12 studies, strongest evidence first
A nine-spice blend that included cloves, eaten in a fatty meal, lowered blood triglycerides by 31% after the meal, but only when people rested afterward
Randomized crossover trial in 20 overweight adults. The 1,000-calorie meal held 14.5 g of a blend of black pepper, cinnamon, cloves, garlic, ginger, oregano, paprika, rosemary and turmeric, or a placebo. Glucose and insulin did not change, and the triglyceride effect vanished when people faced a stress test. The study cannot say what cloves did on their own, and 14.5 g is a large dose of spice for one meal.
A review of spice trials in type 2 diabetes found too few clove studies to test whether cloves change blood sugar
Systematic review of 77 studies, with a meta-analysis of 45, on aromatic herbs and spices in people with type 2 diabetes. Cinnamon, turmeric, ginger, black cumin and saffron lowered fasting glucose. Cloves, along with parsley, thyme, black pepper, rosemary, basil and oregano, had too few trials to pool, so this review shows a gap, not a result.
A clove extract capsule for 30 days lowered blood sugar after meals by about 13 to 17 mg/dL in 13 adults
Open-label pilot with no placebo group, using 250 mg a day of a water-soluble clove polyphenol extract, not the kitchen spice. Seven volunteers had normal fasting glucose and six had slightly high levels, and fasting glucose fell only in the higher group, by about 14 mg/dL by day 30. Some authors work for the companies that make and sell the extract.
A clove bud extract capsule taken with alcohol cut hangover severity by 55% in 16 men, with lower markers of inflammation and oxidative stress
Randomized, double-blind crossover trial. Social drinkers took 250 mg of a standardized clove polyphenol extract or a placebo, then drank alcohol at 1 g per kilogram of body weight. Blood acetaldehyde fell faster, and C-reactive protein and interleukin-6 were lower. The authors work for the company that makes the extract.
A homemade clove gel on the lining of the mouth numbed needle pricks about as well as 20% benzocaine gel in 73 adults
Topical, not eaten. In a randomized, subject-blinded trial, volunteers had clove gel, 20% benzocaine gel or a matching placebo on the mouth lining for 5 minutes before two needle sticks. Pain scores on a 100 mm scale were lower with both gels than with placebo, and clove and benzocaine did not differ. It tested a needle prick in healthy volunteers, not a toothache.
A clove extract mouthwash twice a day for 5 days lowered ventilator-associated pneumonia to 20.2% against 41.7% with chlorhexidine in intensive care patients
Topical, a rinse, not food. Randomized, triple-blind trial in 168 intensive care patients at one hospital in Iran, comparing a 6.66% clove extract mouthwash with the standard 0.2% chlorhexidine rinse. The severity of pneumonia did not differ between the groups. One site and one trial, so it needs repeating.
A 1% clove oil cream on the skin for 6 weeks healed chronic anal fissures in 60% of people against 12% with stool softeners and lignocaine cream
Topical, not eaten. Single-blind randomized trial in 55 people, 30 using clove oil cream and 25 on standard care, checked after 3 months. Pressure in the anal canal also dropped more in the clove oil group. Single-blind and small, so a larger, fully blinded trial would be needed.
In infected mice, a clove preparation lowered Candida yeast counts in the mouth when placed there, and in the stomach and feces when given into the stomach
Mouse model of Candida albicans infection using clove as an herbal food. Placed in the mouth, the preparation improved oral symptoms. Given into the stomach, it did not improve oral symptoms but cut yeast in the stomach and feces. Animals only, with no human trial behind it.
Across rodent studies, eugenol, the main compound of cloves, lowered blood glucose in animals with high blood sugar
Meta-analysis of studies in hyperglycemic rodents. Eugenol also improved blood fats and reduced oxidative, kidney and liver damage, but insulin levels did not change, and the size of the effect depended on the dose and on whether the eugenol was purified. Animal data on one compound, not on cloves in food.
Eugenol and acetyl eugenol from cloves blocked platelet clumping in the lab, more strongly than aspirin
Lab study of platelets. The two compounds, isolated from clove oil, reduced clumping triggered by arachidonate, adrenaline and collagen, and the effect was reversible. Based on the doses tested, both were more potent than aspirin. It does not show that eating cloves thins the blood.
At a low concentration of 2 µM, eugenol blocked human platelets from clumping in the lab and reduced lung clots in mice without lengthening bleeding time
Lab and mouse study of pure eugenol, the main compound of clove oil. It stopped clumping triggered by collagen and arachidonic acid, but not by thrombin or U46619. There is no human trial of eating cloves behind it.
Eugenol, the main flavor compound of cloves, activated the warmth-sensing channel TRPV3 in cells from the tongue and skin
Cell study. Eugenol, carvacrol (oregano) and thymol (thyme) each switched on TRPV3, a channel found in the tongue, skin and nose. The authors link this to the warm feel these flavors give on the tongue, and note that all three can cause skin sensitization. It helps explain the heat of cloves, not a health effect.
Who should be careful with cloves
Most people can eat cloves freely. Take a little care if one of these applies:
- Clove oil and young children. The oil is mostly eugenol and far stronger than the spice: MedlinePlus says as little as 10 mL can seriously harm an adult and smaller amounts a child, and a 15-month-old developed liver failure after 10 mL. Keep it out of reach, skip it for teething in children under 2, and in the US call Poison Help at 1-800-222-1222 if anyone swallows it. Cooking amounts are not the worry, as NIH’s LiverTox says eugenol in therapeutic doses has not been implicated in liver injury.
- Clove cigarettes. They are tobacco products with all the risks of ordinary cigarettes. The American Medical Association’s council also noted lung injury in some smokers, and apparent aspiration pneumonitis in others whose gag reflex was dulled by the numbing action of eugenol in the smoke.
How to choose, store and eat cloves
- Ground: 1 tsp (2.1 g) has 6 calories, 0.7 g of fiber and 55% of the daily value for manganese, so a pinch adds flavor and little else.
- Whole buds: they keep longer in the pantry than ground cloves, 3 to 4 years against 2 to 3 years in one extension guide.
- Clove oil and extracts: not the same as the spice. The extract trials used 250 mg a day, and clove oil should never be swallowed.
Whole buds keep longer than ground cloves, so they suit cooks who use the spice only now and then. A little goes a long way, since a teaspoon is only 2.1 g.
Sources
- Eugenol oil overdose. MedlinePlus Medical Encyclopedia, U.S. National Library of Medicine.
- Eugenol (clove oil). LiverTox: Clinical and Research Information on Drug-Induced Liver Injury. National Institute of Diabetes and Digestive and Kidney Diseases. 2019.
- Janes SE, Price CS, Thomas D. Essential oil poisoning: N-acetylcysteine for eugenol-induced hepatic failure and analysis of a national database. Eur J Pediatr. 2005.
- What is the main toxic component of oil of cloves? Tennessee Poison Center, Vanderbilt University Medical Center. 2025.
- Council on Scientific Affairs. Evaluation of the health hazard of clove cigarettes. JAMA. 1988.
- Schonberger HL, Boyer R. Food storage guidelines for consumers. Virginia Cooperative Extension, Virginia Tech. Revised 2025.
- Spices, cloves, ground. USDA FoodData Central, FDC 171321.
History of cloves
Cloves began on a handful of tiny volcanic islands. Until the colonial era they grew on only a few of the Maluku islands, among them Bacan, Makian, Moti, Ternate and Tidore. For centuries almost every clove in the world came from there.
The oldest cloves found outside the islands turned up in a burned-down house at Terqa, in today’s Syria. They are dated to 1720 BC, and archaeologist Giorgio Buccellati reported them in 1978. Cloves were in Rome by the first century AD, and a record of church gifts under Pope Sylvester I lists 150 Roman pounds of them, about 50 kg.
In the 17th century the Dutch East India Company tried to control the clove trade, as it had done with nutmeg. It struggled because clove trees grew all over the Moluccas, which put the trade beyond the company’s limited policing powers. In 1770, men acting for the French official Pierre Poivre stole seedlings from Ternate and took them to Mauritius and the Seychelles. From there cloves spread to French Guiana, Martinique and Saint-Domingue.
Today Indonesia is still the largest producer, followed by Madagascar, Tanzania, Sri Lanka and the Comoros. Only about 10 to 15% of Indonesia’s harvest is exported, and the country also makes kretek cigarettes, which mix tobacco with cloves. In 2022 researchers published a chromosome-scale clove genome of 370 megabases and proposed that eugenol acetate helps the buds and leaves build up so much eugenol.
Sources
- Otunola GA. Culinary spices in food and medicine: an overview of Syzygium aromaticum (L.) Merr. and L. M. Perry [Myrtaceae]. Front Pharmacol. 2021.
- Ouadi S, Sierro N, Goepfert S, et al. The clove (Syzygium aromaticum) genome provides insights into the eugenol biosynthesis pathway. Commun Biol. 2022.
- Clove. Wikipedia.
- Pérez-Jiménez J, Neveu V, Vos F, Scalbert A. Identification of the 100 richest dietary sources of polyphenols: an application of the Phenol-Explorer database. Eur J Clin Nutr. 2010.
Frequently asked questions about cloves
Are cloves good for you?
In small amounts, yes as a seasoning, but proven health effects are thin. A teaspoon of ground cloves (2.1 g) has 6 calories and 1.26 mg of manganese, 55% of the daily value. All 12 studies here are limited or lab-based, and only one used cloves in a meal: a nine-spice blend that lowered triglycerides by 31% after a fatty meal at rest. The others used extracts, gels, a mouthwash or a cream.
Are cloves high in antioxidants?
Yes, gram for gram they top the lists. A 2010 analysis of 452 foods found 15,000 mg of polyphenols per 100 g in cloves, the highest value on its list of the 100 richest sources. A teaspoon holds roughly 300 mg, and no trial here shows that this amount turns into a health benefit.
Do cloves help with toothache?
A clove gel can numb the mouth lining, but no trial here tested toothache itself. A homemade clove gel eased needle pricks about as well as 20% benzocaine gel in 73 adults. See a dentist if pain lasts, and do not give clove oil to young children.
Do cloves lower blood sugar?
It is not proven. A review of spice trials in type 2 diabetes found too few clove trials to pool, while a 13-person pilot with no placebo group saw after-meal glucose fall by about 13 to 17 mg/dL on 250 mg a day of a clove extract. Rodent studies point the same way, but they used eugenol rather than cloves in food. If you take diabetes medicine, ask your care team before using supplements.
Is clove oil safe?
Not to swallow, and especially not for children. MedlinePlus says as little as 10 mL can seriously harm an adult, and smaller amounts can harm a child. Ground or whole cloves in food are a different matter, since LiverTox found eugenol in therapeutic doses has not been linked to liver injury. In the US, call Poison Help at 1-800-222-1222 if anyone swallows the oil.
Are cloves a good source of manganese?
Yes. A teaspoon of ground cloves has 1.26 mg of manganese, 55% of the daily value, and none of the other 22 herbs and spices on this site has more per teaspoon. Few people eat a full teaspoon in one dish, so a pinch gives far less.
Do cloves go bad?
They lose flavor with time rather than turning unsafe. One extension guide suggests keeping whole spices 3 to 4 years and ground spices 2 to 3 years in the pantry, so whole buds last longer.