Other common name(s): clove oil, oil of cloves (Eugenol)
Scientific/medical name(s): Syzygium aromaticum, Caryophyllus aromaticum, Eugenia caryophyllata, Eugenia aromatica
The clove is a flower bud from an aromatic evergreen tree that grows in the tropics of Asia and South America. The bud and stem of the dried clove is widely as a spice and food flavoring. The oil extracted from the plant, leaves, flower buds, and fruit itself is used in herbal remedies and some dental practices.
Available scientific evidence does not support claims that cloves or clove oil is effective in treating or preventing cancer or any other disease. Some dentists and patients report that clove oil may relieve gum and tooth pain and may be useful as a topical antiseptic in mouthwash; however, there is limited scientific evidence for this.
How is it promoted for use?
Some proponents also claim that cloves and clove oil, when taken internally, relieve nausea and vomiting, improve digestion, fight intestinal parasites, stimulate uterine contractions, ease arthritis inflammation, stop migraine headaches, and ease symptoms of colds and allergies. It’s supposed to help cramping, gas, colic, malaria, tuberculosis, scabies, and improve the memory. Some practitioners claim that a mixture of cloves, black walnut hulls, and wormwood can cure cancer (see our documents Black Walnut and Wormwood).
Practitioners of traditional Chinese medicine sometimes treat hiccups and impotence with cloves (see our document Chinese Herbal Medicine). Clove oil is also used in aromatherapy (see our document Aromatherapy).
What does it involve?
Dried cloves are available in capsules, powder, or as whole flower buds. You can also buy clove oil, either pure or diluted.
What is the history behind it?
Cloves and clove oil were reportedly used in Chinese medicine as early as 600 AD. Cloves have long been a part of various folk medicine traditions around the world. Clove oil has been used by dentists, who swabbed it inside patients’ mouths to lessen the pain of anesthetic injections. Some people still apply it inside the mouth to help toothaches. Today, cloves are also used as an ingredient in baking and cooking and in perfumes, small cigars, mouthwash, and toothpaste.
What is the evidence?
Clove oil has been approved for use in dentistry as a topical anesthetic by Commission E, Germany's regulatory agency for herbs. However, no well-controlled clinical studies have been done to evaluate the potential germ-killing and anticancer properties of cloves or clove oil in humans.
A small controlled study published in 2006 compared clove gel to a numbing gel to lessen the pain of injections in the mouth. The researchers found that people who were given a placebo gel had more pain than those who received clove gel or numbing gel. The pain levels of those who received the numbing medicine and those who were given clove gel were about the same. Further studies are needed to be sure this is a reliable effect.
A few laboratory studies do suggest that clove and clove extracts may be antioxidants. Antioxidants are compounds found in many fruits and vegetables that block the action of free radicals, activated oxygen molecules that can damage cells.
Very limited laboratory studies conducted in other countries suggest that clove oil may fight bacteria, fungi, and even skin mites (scabies). One study compared the oils from several herbs to find out how well they stopped the growth of certain germs in the lab. Clove oil was very effective at stopping the growth of the bacteria, yeasts, and molds that were tested. Along these lines, a Japanese study in mice suggested that a clove preparation taken by mouth might help reduce the severity of yeast infections in the mouth. More recently, a lab study showed that direct exposure to clove oil killed skin mites.
Extracts of cloves: A 2006 study suggested that cloves contain chemicals that might reduce development of lung cancer in mice treated with cancer-causing chemicals. Another laboratory study suggested that compounds taken from cloves show promise as potential anticancer agents. However, study results of clove extracts will not necessarily be the same as studies using the raw plant. And, while laboratory studies may show promise, further studies are needed to find out whether the results apply to humans.
Are there any possible problems or complications?
Cloves are generally considered safe, but a fairly small number of people may be allergic to them. A study of patients from German, Austrian, and Swiss dermatology departments reported in 2010 that 1.5% of those who had skin allergy testing with clove oil had positive results (were allergic to it). Severe reactions may occur in these people. Those known to be allergic to clove or balsam of Peru should avoid using cloves in any form, including use on the skin or inhaling the smoke from clove cigarettes.
Taking in large amounts of cloves or clove oil may cause nausea, vomiting, abdominal pain, diarrhea, burns in the mouth and throat, sore throat, seizures, difficulty breathing, rapid heartbeat, sleepiness, intestinal bleeding, and liver or kidney failure. More serious effects have been reported in young children, even with small doses. Clove supplements may cause bleeding in those taking medicine to stop blood clots (blood thinners). Use of clove supplements during pregnancy is not recommended, although the amounts found in foods are thought to be OK.
Excessive application of undiluted clove oil on or near the teeth may cause irritation or damage to the gums or mouth and may damage the dental pulp, the soft core of the tooth, made up of living soft tissue and cells. It should be used for tooth and gum conditions only under the supervision of a dentist. Undiluted clove oil may cause skin irritation, rashes, or even burns. Clove oil can cause blindness in laboratory animals, so keep clove preparations away from the eyes.
Clove cigarettes, also known as kreteks, are no longer legally sold in the US. Made from tobacco and cloves, kreteks deliver more nicotine, carbon monoxide, and tar than regular cigarettes. In addition to having the same health risks as regular cigarettes, clove cigarettes may also increase the risk of suddenly developing life-threatening fluid buildup in the lungs, as well as serious pneumonia. Rarely, deaths have been reported after smoking kreteks.
Relying on this type of treatment alone and avoiding or delaying conventional medical care for cancer may have serious health consequences.
To learn more
More information from your American Cancer Society
The following information on complementary and alternative therapies may also be helpful to you. These materials may be found on our Web site (www.cancer.org) or ordered from our toll-free number (1-800-227-2345).
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Note: This information may not cover all possible claims, uses, actions, precautions, side effects or interactions. It is not intended as medical advice, and should not be relied upon as a substitute for consultation with your doctor, who is familiar with your medical situation.
Last Revised: 07/22/2011