Medically reviewed on February 15, 2018
Scientific Name(s): Syzygium aromaticum (L.) Merr. and L.M. Perry. Family: Myrtaceae (Myrtle).
Common Name(s): Clove , caryophyllus
Clove has historically been used for its antiseptic and analgesic effects. Clove and clove oils are used safely in foods, beverages, and toothpastes. Clove oil cream has been used in the treatment of anal fissures and an extract has exhibited aphrodisiac action in rats; however, there are limited studies supporting clinical applications for clove oil.
There are limited studies to support therapeutic dosing for clove oil.
Contraindications have not been identified.
Information regarding safety and efficacy in pregnancy and lactation is lacking.
None well documented.
Contact dermatitis has been noted.
Toxicity has been observed following ingestion of the oil, but is rare and poorly documented.
The clove plant grows in warm climates and is cultivated commercially in Tanzania, Sumatra, the Maluku (Molucca) Islands, and South America. The tall evergreen plant grows up to 20 m and has leathery leaves. The strongly aromatic clove spice is the dried flower bud; essential oils are obtained from the buds, stems, and leaves. The dark brown buds are 12 to 22 mm in length and have 4 projecting calyx lobes. The 4 petals above the lobes fold over to form a hood, which hides numerous stamens. 1 , 2 Synonyms are Eugenia caryophyllata , Eugenia caryophyllus , and Caryophyllus aromaticus .
Clove has a long history of culinary and medicinal use. The oil has been used as an expectorant and antiemetic with inconsistent clinical results. Clove tea was used to relieve nausea. Use of the oil in dentistry as an analgesic and local antiseptic continues today. It also has been used topically as a counterirritant. 3
Clove buds yield approximately 15% to 20% of a volatile oil that is responsible for the characteristic aroma and flavor. The stems yield approximately 5% of the oil, and the leaves yield approximately 2%. In addition, the bud contains a tannin complex, gum and resin, and a number of glucosides of sterols.
The principal constituents of distilled clove bud oil (60% to 90%) are the phenylpropanoids, including primarily eugenol (4-allyl-2-methoxyphenol) and carvacrol, thymol, and cinnamaldehyde. The oil also contains approximately 10% acetyleugenol and small quantities of gallic acid, sesquiterpenes, furfural, vanillin, and methyl-n-amyl ketone. Other constituents include flavonoids, carbohydrates, lipids, oleanolic acid, rhamnetin, and vitamins. 3 , 4 , 5 , 6 , 7 Essential oil of the leaf has also been described, similarly containing eugenol, caryophyllene, humulene, and eugenyl acetate. 8 Flavonoid triglycosides have been identified in the seeds, and rapid high-performance chromatographic techniques have been developed for determining phenolic acid content. 9 , 10
Uses and PharmacologyAnesthetic
Eugenol has been used extensively in dentistry for its anesthetic and antianaerobic bacteria activity. 3 , 11 The short duration of effect has been used in anesthesia of fish, such as the rainbow trout, channel catfish, and zebra fish. 3 , 12Clinical data
Clove oil gel (2:3 vol/vol with glycerin) performed as well as benzocaine gel in an experiment evaluating effect on induced pain in the buccal mucosa. 13Antimicrobial
In vitro studies demonstrate activity of clove oil against gram-positive and gram-negative bacteria pathogenic to humans, including multiresistant strains. 3 , 14 , 15 , 16 Activity against listeria in pasteurized milk has been demonstrated, 17 as well as antifungal action in vitro against Candida , Aspergillus , and Trichophyton species. 15 , 16 , 18 , 19 Antiviral activity against herpes simplex and hepatitis C virus has also occurred. 3Animal data
Mice with induced pneumonia showed a decrease in bacterial colonization when fed clove oil for 15 days. 20 Clove oil has been proposed for use in cat and dog ear infections based on in vitro studies. 21Clinical data
In vitro studies have shown antibacterial action against gram-negative anaerobes responsible for acne. 22Cancer
Whole cloves were chemoprotective against liver and bone marrow toxicity in mice. 25 In mice with induced lung cancer, an oral aqueous preparation of whole clove decreased cell proliferation and increased apoptosis. 26Clinical data
There are no clinical evaluations of clove; however, activity against human cancer cell lines has been demonstrated. 3Other uses
The use of 1% clove oil cream resulted in significantly greater healing rates than 5% lignocaine in a small study of anal fissures. 27Antioxidant
Clove oil possesses mosquito repellant and other insecticidal activity. 3 , 32 Eugenol possesses marked antipyretic activity in animals, similar to that of acetaminophen. Enhanced transdermal delivery of ibuprofen by clove oil has been demonstrated in rabbits. 33 Anti-inflammatory activity has been demonstrated in macrophages of mice fed aqueous clove extract. 34 , 35
There are limited studies supporting clinical applications for clove oil.
Information regarding safety and efficacy in pregnancy and lactation is lacking. In a toxicological experiment, clove added to the diet of pregnant mice for 2 weeks resulted in increases in cell death. No effects on pregnant adult mice were noted. 36
Clove oil can be a skin and mucous membrane irritant and sensitizer; contact dermatitis has been noted. 7 , 40 A woman 24 years of age reported permanent local anesthesia and anhidrosis following clove oil spillage onto the facial area. 41
Clove and clove oils are used safely in foods, beverages, and toothpastes. In general, the level of clove used in foods does not exceed 0.24%; the oil is not used in amounts greater than 0.06%. Toxicity has been observed following ingestion of the oil but is rare and poorly documented. 42 , 43 There is no documentation of toxicity in the bud, leaf, or stem of the plant. 7
In rats, the oral median lethal dose (LD 50 ) of eugenol is 2,680 mg/kg; however, the toxicity of the compound increases almost 200-fold when administered intratracheally (LD 50 11 mg/kg). 44
Increased toxicity by the pulmonary route has been reported among people who have smoked clove cigarettes. Clove cigarettes, called “kreteks,” generally contain about 60% tobacco and 40% ground cloves. 45 , 46
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