Cloves (Syzygium aromaticum): Uses, Evidence and Safety
Cloves (Syzygium aromaticum) as a spice and a traditional toothache remedy: what the EU assessment found, how thin the trial evidence is, and why clove oil can poison young children.
Content last updated . This page has not been medically reviewed.
Safety first. Supplements can cause side effects and interact with medicines. Read mushroom safety and interactions before you use any mushroom product.
Safety first: clove oil is far stronger than whole cloves, and swallowing it has caused severe poisoning in young children. The European Medicines Agency (EMA) assessment describes a 3-month-old girl and a 15-month-old boy who developed fulminant liver failure after swallowing clove oil, and a 2-year-old boy who drank 5 to 10 ml and went into a deep coma with severely impaired liver function. [1] If a child may have swallowed clove oil or any essential oil, call 911 or Poison Help at 1-800-222-1222 (US) right away, and see what to do if a child swallowed a natural product. Oil is covered on its own page: clove oil.
Overview
Cloves are the dried flower buds of Syzygium aromaticum (L.) Merr. & L.M.Perry, family Myrtaceae. [2] An older name, Eugenia caryophyllus, is still listed by the EMA as a synonym. [3] The most important chemicals in clove oil are eugenol, eugenyl acetate and beta-caryophyllene. [4] This page is about the spice (whole or ground cloves). It gives no instructions for making oils, gels or other preparations at home, and no amounts for readers. For cooking, see saffron, cloves and other whole spices as food.Traditional use (not proof of benefit)
The EMA's herbal committee (HMPC) found consistent data on a traditional use of cloves for the short-term suppression of toothache. [1] Cloves were also traditionally used for indigestion, flatulence and diarrhea. [1] The assessor noted that clove for toothache "will be taken from food and not from medicinal products." [1] Traditional use tells us what people did, not whether it works.What research shows
| Use | What the source found | Strength of evidence | Form and population |
|---|---|---|---|
| Toothache | The EMA found a lack of controlled clinical studies using clove preparations. [1] | Traditional use only | Whole cloves and oil, adults |
| Surface numbing before a needle in the mouth | In a randomized, subject-blinded trial, a clove gel and a benzocaine gel both gave lower pain scores than placebo, with no difference between clove and benzocaine. [5] | Promising but limited (one small trial; not a toothache study) | Gel on gum tissue, 73 adult volunteers |
| Infections, inflammation, cancer, diabetes and other uses | Reviews describe activity in cells and animals. [4] Proper evidence not found for human trials in the sources we read (we searched PubMed for clove and Syzygium aromaticum reviews and trials, and the EMA herbal pages). | Preclinical (cells or animals) | Extracts, oil and eugenol |
A result for one form does not carry to another. A gel tested in volunteers says nothing about swallowing the oil, and a lab result for eugenol says nothing about the spice in food.
Forms and why the form matters
Whole or ground cloves are a spice. Clove oil is concentrated and is the form linked to the severe poisonings above. [1] See culinary amounts vs supplement amounts.Safety
- Medicines and bleeding. Laboratory work found clove oil inhibited platelet clumping in vitro, and a reference cited by the EMA says its antiplatelet effect may increase bleeding risk with blood-thinning medicines. [1] The EMA assessor called these interactions theoretical for short-term dental use. [1] Treat this as laboratory and theoretical, not proven in people. The same source says clove may cause a falsely raised phenytoin test result. [1] See herbs and blood thinners and how interactions work.
- Surgery. No surgery-specific study was found. Because of the theoretical bleeding effect, tell the surgical team about clove products: herbs before and after surgery.
- Pregnancy and breastfeeding. The EMA found no data and does not recommend medicinal use in pregnancy or lactation. [1] Food amounts are not addressed in the sources we read. See pregnancy and breastfeeding.
- Children. Oil poisoning is documented, as above. [1]
- Liver. Besides the infant liver failure above, rats given a clove decoction for 90 days had altered liver enzymes, and the authors advised avoiding prolonged use of decoctions. [1] That is animal data. Liver warning signs: liver injury warning signs.
- Allergy and irritation. In one patch-test study, 8 of 30 patients reacted to a clove extract. [1] Clove oil in high strength is a local irritant, and allergic reactions are possible. [1] The EMA says medicinal clove oil should not be used by people hypersensitive to it. [1]
- Kidney. Not described in the sources we read.
- Clove cigarettes. These are tobacco products, and the American Medical Association's 1988 review linked their smoke to severe lung injury in a few susceptible people. [6]
Quality
Quality of clove products is not described in the sources we read. For products in general see quality testing and certifications.Official statements
- European Medicines Agency, HMPC (EU), 2011: no European herbal monograph was set for clove flower buds, partly because no single-ingredient clove products were found on the EU market. [7] The assessment found toothache use traditional and plausible, noted safety concerns about eugenol in the oil, and advised dental attention as soon as possible when oil is used for toothache. [1]
Frequently asked questions
Do cloves cure a toothache?
No source we read shows that. The EMA found traditional use for short-term relief but no controlled clinical studies, and it says relief with the oil is only provisional and dental attention should be sought as soon as possible. [1]
Is clove oil safe for children?
No. Reports collected by the EMA describe liver failure and coma in infants and toddlers who swallowed clove oil. [1] Call Poison Help at 1-800-222-1222 (US) or 911 if a child has swallowed any.
Are cloves a blood thinner?
Clove oil reduced platelet clumping in laboratory tests, and a theoretical bleeding risk with blood thinners is noted. [1] It has not been shown in people in the sources we read. Ask a pharmacist if you take anticoagulants.
Are cloves safe in pregnancy?
For medicinal use the EMA found no data and does not recommend it. [1] Ask your clinician about amounts beyond cooking.
Are clove cigarettes safer than regular cigarettes?
No. They are tobacco products with the hazards of smoking, and their smoke has been linked to severe lung injury in some people. [6]
References
- European Medicines Agency, HMPC, Final assessment report on Syzygium aromaticum, flos and floris aetheroleum (EMA/HMPC/534946/2010), adopted 2011. Read 2026-10-23.
- GBIF Backbone Taxonomy, Syzygium aromaticum (L.) Merr. & L.M.Perry. Read 2026-10-23.
- European Medicines Agency, Caryophylli flos - herbal medicinal product (clove), EMA herbal medicines page. Read 2026-10-23.
- Batiha et al., Biomolecules 2020, Syzygium aromaticum: traditional uses, constituents, pharmacological and toxicological activities. PubMed 32019140. Read 2026-10-23.
- Alqareer et al., J Dent 2006, clove and benzocaine versus placebo as topical anesthetics. PubMed 16530911. Read 2026-10-23.
- Council on Scientific Affairs, JAMA 1988, Evaluation of the health hazard of clove cigarettes. PubMed 3057254. Read 2026-10-23.
- European Medicines Agency, HMPC, Public statement on Syzygium aromaticum, flos (EMA/HMPC/112102/2011), 22 November 2011. Read 2026-10-23.