7. Clove
The "fragrant rivet" — eugenol, antimicrobial power, and the science of the toothache tradition.
Clove in 1 minute
What does it provide? Eugenol (70–90% of the essential oil) and β-caryophyllene — antimicrobial, local anesthetic, anti-inflammatory, and antioxidant.
How much? In the kitchen, 1–4 whole clove buds (≈ 0.1–0.3 g) per meal. Traditional topical use: 1 drop of clove oil for toothache (short-term).
When to avoid? Alongside anticoagulants in high-dose extract, in pregnancy the essential oil internally, in infants topically, eugenol sensitivity, in liver disease as a high-dose supplement.
Clove originally is native to the Maluku Islands (today's Indonesia), and around 200 BCE already appears in Chinese imperial sources — during the Han dynasty, officials chewed clove in their mouths before imperial audiences so that their breath would be fragrant. It reached the Greco-Roman world in Pliny's time as part of "Indian pepper" blends. Medieval Arab physicians (Avicenna) recommended it for digestive complaints, and it was one of the most expensive spices on the Silk Road — at the end of the 13th century, Marco Polo separately mentions it in his Venetian travelogue.
The 16th–17th century is clove's "golden age": the Portuguese, then Dutch, colonial empires warred over a monopoly on the Maluku Islands. The Dutch East India Company in 1652 staged bloody destruction to monopolize clove cultivation — all clove trees outside the island of Ambon were destroyed. The monopoly was broken in 1770, when a French colonial official, Pierre Poivre, smuggled seedlings out to Mauritius and Zanzibar. Research on chemical activity began in 1858 with the isolation of eugenol, and in 20th-century dentistry, clove oil (the classic "zinc-oxide-eugenol" filling) became a standard local anesthetic.[2275][2276]
Scientific Background
Clove's main bioactive is eugenol (4-allyl-2-methoxyphenol), which makes up 70–90% of the bud's essential oil — this is one of the most concentrated natural eugenol sources. Eugenol acts through several parallel mechanisms: TRPV1 and TRPA1 receptor modulation (local anesthesia), NF-κB inhibition (anti-inflammation), and very strong antimicrobial activity against Gram-positive and Gram-negative bacteria, as well as Candida albicans.[2279]
The dental local anesthetic effect is clinically confirmed — in a randomized double-blind trial (Alqareer 2006), clove gel reduced injection needle-prick pain equivalently to benzocaine.[2274] "Zinc-oxide-eugenol" paste is still used today for dental fillings and root canal treatments.
Its antimicrobial spectrum in vitro is impressive: effective against food pathogens (Listeria, Salmonella, E. coli), H. pylori[2280], and oral microbiome pathogens (Streptococcus mutans).[2278] Clinically, however, it is not an antibiotic substitute.
Anticoagulant effect: eugenol inhibits platelet aggregation and prostaglandin synthesis — high-dose supplementation alongside anticoagulant therapy adds bleeding risk.
At the microbiome level, eugenol's selective antimicrobial effect in mouse models in vivo showed relative growth of Lactobacillus and support of commensal balance.
- + Cinnamon, cardamom, clove, pepper (chai/garam masala): classic Indian synergy.
- + Hot drink (mulled wine, tea, chocolate): essential oil dissolves well.
- + Meat marinade: antimicrobial preservation + flavor depth.
- + Honey (for toothache): 1 drop of clove oil + 1 tsp of honey, short-term topical relief.
- + Baked goods (lebkuchen, gingerbread): classic Christmas pattern.
- + Polyphenol-rich matrix (red wine, red berries): flavor harmony + antioxidant synergy.
- Anticoagulants (warfarin, DOAC, aspirin, clopidogrel) + high-dose clove extract: additive bleeding risk.
- Eugenol oil held in larger amounts under the tongue: severe oral mucosa irritation, burn injury.
- Applied in the mouth of an infant: severe hepatotoxicity cases documented (USA, FDA warning).[2277]
- Heated eugenol oil + open wound: tissue irritation, possible necrosis.
- Long simmer (30+ min at high heat): essential oil evaporates.
- Concentrated extract on empty stomach: GI irritation.
- Coagulation disorder, anticoagulant therapy: high-dose supplement to be avoided.
- Infant (< 2 years): topical clove oil for toothache to be avoided — hepatotoxicity cases.
- Pregnancy, breastfeeding: essential oil internally to be avoided, culinary dose safe.
- Active gastric ulcer: concentrated extract irritates.
- Eugenol allergy (contact cheilitis): topical avoidance.
- Severe liver disease: high-dose supplement to be avoided.
- Planned surgery within 2 weeks: stop high-dose supplement.
- G6PD deficiency: theoretical hemolysis trigger at high-dose eugenol.
Daily serving
1–4 whole clove buds (≈ 0.1–0.3 g) per meal; in ground form ¼–½ tsp for baking recipes.
Preparation pattern
- Whole bud: in mulled drink, in sauce, 5–10 min — essential oil dissolves well.
- Studding an onion with clove: bay leaf + clove + onion → classic "bouquet garni" for meat stock.
- In baking, can be added directly into the dough (lebkuchen, gingerbread).
- Remove the whole buds before serving — so they don't accidentally crack under a guest's tooth.
Classic patterns
Mulled wine: red wine + clove + cinnamon + nutmeg + orange peel + sugar.
Garam masala: clove + cinnamon + cardamom + cumin + pepper.
Ham glaze: roast ham + studded clove + brown sugar + Dijon mustard.
Pho (Vietnamese soup): clove + anise + cinnamon + ginger + beef bone broth.
Storage and what to avoid
Storage: whole bud 2 years, airtight, in a dark place; ground powder 6 months.
What not to do: don't give clove oil to an infant, don't arbitrarily combine clinical-dose supplements with warfarin, don't swallow the whole bud (not dangerous, but can be tooth-damaging).
References
[2274] Alqareer A et al. The effect of clove and benzocaine versus placebo as topical anesthetics2006;34(10):747–750. J Dent. Link
OBJECTIVES: The purpose of this study was to examine whether the natural herb clove can replace benzocaine as a topical anesthetic. METHODS: Topical agents were applied to the maxillary canine buccal mucosa of 73 adult volunteers. Four substances were tested in the study: (1) homemade clove gel, (2) benzocaine 20\% gel, (3) placebo that resembles clove and (4) a placebo that resembled benzocaine. After 5 min of material application in a randomized, subject-blinded manner, each participant received two needle sticks. Pain response was registered using a 100 mm visual analogue pain scale. RESULTS: Both clove and benzocaine gels had significantly lower mean pain scores than placebos (p=0.005).
[2275] Cortés-Rojas DF et al. Clove (Syzygium aromaticum): a precious spice2014;4(2):90–96. Asian Pac J Trop Biomed. Link
Clove (Syzygium aromaticum) is one of the most valuable spices that has been used for centuries as food preservative and for many medicinal purposes. Clove is native of Indonesia but nowadays is cultured in several parts of the world including Brazil in the state of Bahia. This plant represents one of the richest source of phenolic compounds such as eugenol, eugenol acetate and gallic acid and posses great potential for pharmaceutical, cosmetic, food and agricultural applications. This review includes the main studies reporting the biological activities of clove and eugenol. The antioxidant and antimicrobial activity of clove is higher than many fruits, vegetables and other spices and should deserve special attention. A new application of clove as larvicidal agent is an interesting strategy to combat dengue which is a serious health problem in Brazil and other tropical countries.
[2276] Pulikottil SJ, Nath S. Potential of clove of Syzygium aromaticum in development of a therapeutic agent for periodontal disease: a review 2015;70(3):108–115. South Afr Dent J. 2015.
Review (South Afr Dent J, 2015) on the potential of clove (Syzygium aromaticum) in developing a therapeutic agent for periodontal disease.
[2277] FDA. Clove oil — pediatric warning notice.
FDA pediatric warning notice on clove oil.
[2278] Chaieb K et al. The chemical composition and biological activity of clove essential oil, Eugenia caryophyllata 2007;21(6):501–506. Phytother Res. 2007. Link
Short review of the chemical composition and biological activity of clove essential oil (Eugenia caryophyllata / Syzygium aromaticum). The main constituents are phenylpropanoids, chiefly eugenol. The authors summarize its antimicrobial, antioxidant, antifungal and antiviral activity (tested pathogens include bacteria, Herpes simplex and hepatitis C virus), as well as anti-inflammatory, cytotoxic, insect-repellent and anaesthetic properties, including new findings against multi-resistant Staphylococcus epidermidis.
[2279] Pramod K et al. Eugenol: a natural compound with versatile pharmacological actions 2010;5(12):1999–2006. Nat Prod Commun. 2010.
Review (Nat Prod Commun, 2010) on eugenol as a natural compound with versatile pharmacological actions.
[2280] Xu JG et al. Clove oil — Helicobacter pylori in vitro 2015. Helicobacter. 2015.
In vitro study (Helicobacter, 2015) on clove oil against Helicobacter pylori.