Clove

The medicinal part is the dried, unopened flower bud, used whole, powdered, or as the distilled essential oil.

Clove’s best-known use is for toothache. A whole clove held against the tooth, or a drop of the oil on cotton wool, numbs the area. Dentistry still uses eugenol in zinc oxide–eugenol dressings for dry socket ^{4Reference 4Daly BJ et al. · 2022Systematic reviewLocal interventions for the management of alveolar osteitis (dry socket) — [systematic review]View study →}.

Clove is also a warming aromatic: a carminative for sluggish digestion, wind and nausea, an antiseptic for minor wounds, and a warming remedy during colds ^{30,34Reference 30Batiha GE et al. · 2020ReviewSyzygium aromaticum L. (Myrtaceae): Traditional Uses, Bioactive Chemical Constituents, Pharmacological and Toxicological Activities — [review]View study →Reference 34Orwa C et al. · 2009Syzygium aromaticum — [species database]View study →}.

Clove is Ding Xiang (丁香), the “nail fragrance”, a shape metaphor like the English name.

It is classified as acrid and warm, entering the Spleen, Stomach and Kidney channels, and it belongs to the herbs that warm the interior. Its function is to warm the middle burner and direct rebellious Qi downward, the Chinese framing of nausea, hiccup and vomiting.

It is used for vomiting and hiccup from cold in the stomach, for poor appetite and cold abdominal pain, and, through its Kidney-warming action, for impotence and cold in the lower body.

In Ayurveda clove is lavanga, a pungent, heating spice used for cough, colds, poor digestion and toothache.

In a randomized, subject-blinded trial in 73 adults, a homemade clove gel lowered pain scores from needle sticks into the gum compared with placebo, and did not differ from benzocaine 20% gel ^{1Reference 1Alqareer A et al. · 2006RCTThe effect of clove and benzocaine versus placebo as topical anesthetics — [randomised controlled trial]View study →}.

Eugenol inhibits voltage-gated sodium channels in excitable tissue, the same target class as conventional local anaesthetics ^{2,3Reference 2Teixeira-Fonseca JL et al. · 2021In vitroEugenol interacts with cardiac sodium channel and reduces heart excitability and arrhythmias — [animal in vivo / in vitro]View study →Reference 3Tsuchiya H · 2017ReviewAnesthetic Agents of Plant Origin: A Review of Phytochemicals with Anesthetic Activity — [review]View study →}.

It is the active ingredient of zinc oxide–eugenol dental dressings. Clove preparations appear in reviews of local treatments for dry socket and for pain in the mouth and face ^{4,5Reference 4Daly BJ et al. · 2022Systematic reviewLocal interventions for the management of alveolar osteitis (dry socket) — [systematic review]View study →Reference 5Barrera SD et al. · 2024Meta-analysisHerbal extracts in orofacial pain: a systematic review and direct and indirect meta-analysis — [systematic review and meta-analysis]View study →}.

Clove is also one of nine herbs in SS-cream, a topical formula studied for premature ejaculation. Its own contribution cannot be separated from the blend ^{28,29Reference 28Choi HK et al. · 2000RCTClinical study of SS-cream in patients with lifelong premature ejaculation — [randomised controlled trial]View study →Reference 29Shah MDA et al. · 2023Meta-analysisTopical Anesthetics and Premature Ejaculation: A Systematic Review and Meta-Analysis — [systematic review and meta-analysis]View study →}.

All of this is topical and local. None of it supports pain relief taken by mouth.

Gap: the trial used a non-standardised homemade gel, so no effective eugenol concentration has been defined, and nothing compares how long the effect lasts against lidocaine. Clove relieves a toothache for a while; it does not treat the cause, and the tooth still needs a dentist ^{33Reference 33European Medicines Agency · 2011ReviewCommunity herbal monograph on Syzygium aromaticum (L.) Merill et LView study →}.

Clove oil and eugenol show broad antibacterial activity in the laboratory against Gram-positive and Gram-negative bacteria and oral pathogens. Mechanistic work attributes this to damage to the bacterial cell membrane, leakage of cell contents, and interference with efflux pumps and biofilm formation ^{6Reference 6Marchese A et al. · 2017ReviewAntimicrobial activity of eugenol and essential oils containing eugenol: A mechanistic viewpoint — [review]View study →}.

Against antibiotic-resistant Vibrio parahaemolyticus, eugenol at 0.1–0.6% reduced biofilm formation, metabolic activity and extracellular polysaccharide. At 0.4% it removed established biofilms from crab shell surfaces ^{7Reference 7Ashrafudoulla M et al. · 2020In vitroAntibacterial and antibiofilm mechanism of eugenol against antibiotic resistant Vibrio parahaemolyticus — [in vitro]View study →}.

Encapsulated clove essential oil keeps its antibacterial and antioxidant activity, which has drawn interest for food preservation ^{8,9Reference 8Radünz M et al. · 2019In vitroAntimicrobial and antioxidant activity of unencapsulated and encapsulated clove (Syzygium aromaticum, L.) essential oil — [in vitro]View study →Reference 9Valarezo E et al. · 2025Systematic reviewAntioxidant Application of Clove (Syzygium aromaticum) Essential Oil in Meat and Meat Products: A Systematic Review — [review]View study →}.

All of this is laboratory work on the oil or the purified compound at concentrations well above dietary exposure. There is no clinical antibacterial data.

Clove is among the most phenolic-rich spices. Both the essential oil and the bud’s non-volatile fraction (gallic acid, hydrolysable tannins, caffeic acid, kaempferol) show strong radical-scavenging capacity in standard laboratory assays ^{9,10Reference 9Valarezo E et al. · 2025Systematic reviewAntioxidant Application of Clove (Syzygium aromaticum) Essential Oil in Meat and Meat Products: A Systematic Review — [review]View study →Reference 10Abdelmuhsin AA et al. · 2025In vitroClove (Syzygium aromaticum) Pods: Revealing Their Antioxidant Potential via GC-MS Analysis and Computational Insights — [in vitro]View study →}.

Eugenol itself is a potent antioxidant, and its redox activity has been proposed as the source of much of clove’s anti-inflammatory and tissue-protective activity ^{11Reference 11Barboza JN et al. · 2018ReviewAn Overview on the Anti-inflammatory Potential and Antioxidant Profile of Eugenol — [review]View study →}.

The signal is well replicated but confined to chemical and cell-based assays. No human study has measured oxidative-stress markers after clove intake.

In mouse macrophages, clove extract inhibited IL-1β, IL-6 and IL-10 production, and eugenol inhibited IL-6 and IL-10 but not IL-1β. The authors attributed the effect to suppression of the NF-κB pathway by eugenol ^{12Reference 12Bachiega TF et al. · 2012In vitroClove and eugenol in noncytotoxic concentrations exert immunomodulatory/anti-inflammatory action on cytokine production by murine macrophages — [in vitro]View study →}.

A structural relative, ortho-eugenol, showed pain-relieving and anti-inflammatory activity in rodents ^{13Reference 13Fonsêca DV et al. · 2016AnimalOrtho-eugenol exhibits anti-nociceptive and anti-inflammatory activities — [animal in vivo]View study →}. Reviews map eugenol’s action onto NF-κB, COX-2/PGE2 and cytokine pathways ^{11Reference 11Barboza JN et al. · 2018ReviewAn Overview on the Anti-inflammatory Potential and Antioxidant Profile of Eugenol — [review]View study →}.

All of this is preclinical. No human inflammatory-disease trial has been done, and the doses used in cells and rodents do not translate into a defined human regimen.

Clove essential oil and eugenol were active against all the Candida strains tested from the mouths of patients with blood cancers, with MICs of 0.25–2 mg/mL. Both bind ergosterol in the yeast cell membrane. Combined with the oral antiseptics chlorhexidine, cetylpyridinium chloride, silver nitrate and triclosan, they had synergistic or additive effects; with nystatin they did not ^{14Reference 14Biernasiuk A et al. · 2022In vitroClove Essential Oil and Its Main Constituent, Eugenol, as Potential Natural Antifungals against Candida sppView study →}.

Clove oil was one of seven essential oils tested against C. albicans, C. glabrata and C. tropicalis in liquid and vapour-phase assays. Thyme and pine oils were the most active ^{15Reference 15Mandras N et al. · 2016In vitroLiquid and vapour-phase antifungal activities of essential oils against Candida albicans and non-albicans Candida — [in vitro]View study →}.

This supports interest in clove as a topical antifungal, but it remains at the laboratory stage. There is no clinical antifungal data.

Eugenol protects the rat stomach in several ulcer models. In an ethanol-ulcer model, low single doses reduced the ulcer index, raised prostaglandin E2 and lowered TNF-α and IL-6 ^{16Reference 16Hobani YH et al. · 2022AnimalGastroprotective effect of low dose Eugenol in experimental rats against ethanol induced toxicity — [animal in vivo (rat model)]View study →}.

Against indomethacin-induced ulcers, a single 100 mg/kg dose given an hour beforehand reduced the lesions. The protection involved opening ATP-sensitive potassium channels, free-radical scavenging, lower acid-pepsin secretion and more mucin ^{17Reference 17Morsy MA et al. · 2008AnimalMechanisms of gastroprotective effect of eugenol in indomethacin-induced ulcer in rats — [animal in vivo (rat model)]View study →}.

The effect depends on the dose. In rats with chronic acetic-acid ulcers treated twice a day, eugenol at 1 mg/kg sped healing by 33% at 7 days and 52% at 14 days. At 10 mg/kg it had no effect, and at 100 mg/kg for 7 days it enlarged the ulcerated area by 49% ^{18Reference 18Longo B et al. · 2021AnimalDual role of eugenol on chronic gastric ulcer in rats: Low-dose healing efficacy and the worsening gastric lesion in high doses — [animal in vivo (rat model)]View study →}.

Gap: eugenol protects the rat stomach at low doses and worsened chronic ulcers at a high repeated dose. No human gastric study exists either way.

At 2 µM, eugenol inhibited collagen- and arachidonic-acid-induced aggregation of human platelets in the laboratory, without affecting thrombin- or U46619-induced aggregation. In mice it reduced lung vessels blocked by platelet clots without prolonging bleeding time ^{19Reference 19Huang WC et al. · 2024AnimalEugenol Suppresses Platelet Activation and Mitigates Pulmonary Thromboembolism in Humans and Murine Models — [human ex vivo and mouse model]View study →}.

Separately, eugenol blocked the main heart sodium channel (Nav1.5) in cells. In guinea-pig atria it reduced the force and rate of contraction and lessened ouabain-induced rhythm disturbance ^{2Reference 2Teixeira-Fonseca JL et al. · 2021In vitroEugenol interacts with cardiac sodium channel and reduces heart excitability and arrhythmias — [animal in vivo / in vitro]View study →}.

Reviews add anti-atherosclerotic, lipid-lowering and blood-pressure-lowering actions from preclinical data ^{20Reference 20Liu XY et al. · 2025ReviewCardiovascular protective properties of the natural product eugenol — [review]View study →}.

Gap: the antiplatelet effect is the basis of the cardiovascular interest, and it is also a possible interaction with anticoagulant and antiplatelet drugs. No human outcome or dosing trial exists.

A meta-analysis of studies in hyperglycaemic rodents found that eugenol lowered blood glucose and the activity of carbohydrate-digesting enzymes, improved blood lipids, and reduced oxidative, kidney and liver damage. Insulin levels did not change ^{21Reference 21Carvalho RPR et al. · 2021Meta-analysisEffect of eugenol treatment in hyperglycemic murine models: A meta-analysis — [meta-analysis (animal)]View study →}.

In diabetic mice, eugenol increased GLUT4 transport and AMPK activation in skeletal muscle, raising glucose uptake ^{22Reference 22Jiang Y et al. · 2022AnimalEugenol improves high-fat diet/streptomycin-induced type 2 diabetes mellitus (T2DM) mice muscle dysfunction by alleviating inflammation and increasing muscle glucose uptake — [animal in vivo (mouse model)]View study →}.

A systematic review of Mediterranean-diet spices in people with type 2 diabetes looked for clove trials, but found too few to include clove in its meta-analysis. Cinnamon, turmeric, ginger, black cumin and saffron did improve fasting glucose ^{23Reference 23Garza MC et al. · 2024Meta-analysisEffect of Aromatic Herbs and Spices Present in the Mediterranean Diet on the Glycemic Profile in Type 2 Diabetes Subjects: A Systematic Review and Meta-Analysis — [systematic review and meta-analysis]View study →}.

Gap: the positive data are from animals only, and clove’s effect on blood sugar in people has not been measured.

Inhaled eugenol reduced fatty liver in mice fed a high-fat diet, acting through a liver olfactory receptor (Olfr544) and changes in gut bacteria ^{24Reference 24Wang XR et al. · 2025AnimalInhaling Eugenol Inhibits NAFLD by Activating the Hepatic Ectopic Olfactory Receptor Olfr544 and Modulating the Gut Microbiota — [animal in vivo (mouse model)]View study →}. In a rat liver-cancer model it improved liver enzymes ^{25Reference 25Zaky MY et al. · 2025In vitroAnticancer potential of eugenol in hepatocellular carcinoma through modulation of oxidative stress, inflammation, apoptosis, and proliferation mechanisms — [animal in vivo (rat model) and in vitro]View study →}.

In healthy rats given eugenol for 60 days, 10 mg/kg caused no harm, but 20 and 40 mg/kg damaged the structure and function of the liver ^{26Reference 26Carvalho RPR et al. · 2022AnimalHigh doses of eugenol cause structural and functional damage to the rat liver — [animal in vivo (rat model)]View study →}. A computer-modelling study links eugenol-type phenols to liver injury through EGFR, SRC and TNF targets ^{27Reference 27Wang W · 2025In vitroUnveiling the toxicity secrets of eugenol-like compounds: from interaction mechanisms to treatment strategies — [in silico / in vitro]View study →}.

Gap: swallowing concentrated clove oil has caused serious liver injury, especially in young children ^{33Reference 33European Medicines Agency · 2011ReviewCommunity herbal monograph on Syzygium aromaticum (L.) Merill et LView study →}. Protection and damage are both dose-dependent and both rodent-only, and no human liver benefit has been shown.

In one study, eugenol reduced the viability of HepG2 liver-cancer cells (IC50 about 189 µg/mL) and slowed their migration. In rats with chemically induced liver cancer, 20 mg/kg every other day for 17 weeks improved liver histology and lowered ALT, AST, AFP and NF-κB-linked markers ^{25Reference 25Zaky MY et al. · 2025In vitroAnticancer potential of eugenol in hepatocellular carcinoma through modulation of oxidative stress, inflammation, apoptosis, and proliferation mechanisms — [animal in vivo (rat model) and in vitro]View study →}.

This is single-compound work in one model system, with no independent replication in the clove literature and no human data.

Swallowed oil. Concentrated clove oil is the main hazard. After 5–10 mL of oil by mouth, children under 2 have developed life-threatening poisoning. Overdose can cause central nervous system depression, acidosis, liver damage, low blood sugar, seizures and coma. Treatment is supportive, and N-acetylcysteine has been used successfully as an antidote ^{33Reference 33European Medicines Agency · 2011ReviewCommunity herbal monograph on Syzygium aromaticum (L.) Merill et LView study →}.

Dose and the liver. In rats, eugenol at 20 and 40 mg/kg a day for 60 days damaged the liver, while 10 mg/kg did not ^{26Reference 26Carvalho RPR et al. · 2022AnimalHigh doses of eugenol cause structural and functional damage to the rat liver — [animal in vivo (rat model)]View study →}.

Use in the mouth. The oil can irritate the gums and the lining of the mouth, and allergic reactions have been reported. When treating a tooth, the oil should be kept off the gums. People allergic to Peru balsam should not use it ^{33Reference 33European Medicines Agency · 2011ReviewCommunity herbal monograph on Syzygium aromaticum (L.) Merill et LView study →}.

Children. The EMA monograph does not recommend clove oil products for children and adolescents under 18, because there is not enough data ^{33Reference 33European Medicines Agency · 2011ReviewCommunity herbal monograph on Syzygium aromaticum (L.) Merill et LView study →}.

Bleeding. Eugenol inhibits human platelet aggregation in the laboratory ^{19Reference 19Huang WC et al. · 2024AnimalEugenol Suppresses Platelet Activation and Mitigates Pulmonary Thromboembolism in Humans and Murine Models — [human ex vivo and mouse model]View study →}, which suggests care alongside anticoagulant and antiplatelet drugs and before surgery. In mice it did not prolong bleeding time ^{19Reference 19Huang WC et al. · 2024AnimalEugenol Suppresses Platelet Activation and Mitigates Pulmonary Thromboembolism in Humans and Murine Models — [human ex vivo and mouse model]View study →}, and the EMA lists no reported interactions ^{33Reference 33European Medicines Agency · 2011ReviewCommunity herbal monograph on Syzygium aromaticum (L.) Merill et LView study →}.