Clove

Cloves (Syzygium aromaticum, also known as Eugenia caryophyllata) are the aromatic flower buds of a tree in the Myrtaceae family native to Indonesia. The essential oil of clove is known to exhibit antioxidant, anti-inflammatory, antimicrobial, antifungal, antiviral, anticancer, cytotoxic, insect repellent, and anesthetic activities.^1,2 It is used topically in herbal medicine to alleviate pain and facilitate healing,³ and has been used in traditional medicine to confer analgesic, anti-inflammatory, antimicrobial, antiviral, and antiseptic activity.⁴ Cloves also are used in fragrances and for food flavoring.²

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The two main constituents of clove oil are eugenol (78%) and beta-caryophyllene (13%). Although clove oil and its primary components are generally recognized as safe, a 2006 in vitro study by Prashar et al. found that clove oil and eugenol displayed cytotoxicity toward human fibroblasts and endothelial cells. Clove oil, in concentrations as low as 0.03%, was noted for being exceedingly cytotoxic, with up to 73% of this effect ascribed to eugenol, with beta-caryophyllene displaying no toxicity.³ In addition to beta-caryophyllene and the phenylpropanoid eugenol, other important constituents of clove essential oil are the phenylpropanoids carvacrol, thymol, and cinnamaldehyde.²

Topical applications and human studies

Clove oil has been used topically to treat several dermatologic conditions, with its nerve-blocking activity attributed to its primary active constituent, eugenol.⁵ It also has been used as a penetration enhancer in various forms of topical products, including creams, ointments, gels, and patches.⁶

Palmar hyperhidrosis

In 2017, Ibrahim et al. treated 45 patients with palmar hyperhidrosis with clove oil 45% in liposome, with 20 patients in a control group treated with 0.9% saline solution. Subjects were assessed by gravimetry testing and hyperhidrosis disease severity scale to determine the impact of clove oil on decreasing the sweating rate in patients with idiopathic palmar hyperhidrosis. Gravimetry testing revealed that the sweating rate decreased significantly in the clove oil group but that there was no significant improvement in the placebo group. The investigators concluded that twice-daily topical application of 45% clove oil in liposome for 2 weeks showed promise in significantly reducing palmar sweating.⁵

Pruritus

That same year Ibrahim et al. evaluated the effects of topically applied clove oil in treating 50 patients with chronic pruritus due to hepatic, renal, or diabetic origin. The investigators divided the subjects into two groups of 25, with the first directed to hydrate their skin before applying topical clove oil twice daily for 2 weeks. The second group was instructed to apply topical petrolatum by hand on the same schedule. Using the 5-D itch scale, researchers noted a significant improvement in all parameters in the patients using clove oil and no such improvements in the petrolatum group. They concluded that topical clove oil is an effective, safe, inexpensive, and easy-to-use therapy for chronic pruritus, particularly for patients whose topical or systemic treatments are not well tolerated or are contraindicated.⁷

Anal fissure

In 2007, Elwakeel et al. evaluated the use of a clove oil 1% cream for the treatment of chronic anal fissure as opposed to the traditional treatment of stool softeners and lignocaine cream 5% in a single-blind randomized comparative trial over 6 weeks. Healing was observed in 60% of the 30 patients in the clove oil group and in 12% of the 25 patients in the control group at the 3-month follow-up visit. The researchers concluded that topically applied clove oil cream yielded significant benefits in the treatment of chronic anal fissures.⁸