• Essential Oils
• Inhaled: Reducing
Aromatherapy is actually a form of herbal medicine. However, instead of using the entire herb, it employs the fragrant "essential oil" that is released when a fresh herb is compressed or subjected to chemical extraction. Essential oils are also often used as fragrances in cosmetics and bath products.
When employed medicinally, essential oils are often evaporated into the air through the use of a humidifier. The famous Vicks VapoRub® is a gel form of the essential oils of peppermint, eucalyptus, and camphor. Essential oils may also be applied directly to the skin or clothes so they will release their odor near the patient.
Essential oils may be inhaled, taken by mouth, or applied to the skin.
What Is Aromatherapy Used For?
Inhaled aromatherapy has become a popular, gentle treatment to reduce mild anxiety. It has also been tried for a variety of other conditions, including respiratory problems, postsurgical nausea, menstrual pain, and tension headaches.
Topical treatment with essential oils has shown possible value for fungal infections and hair loss. Oral use of essential oils has shown promise for various digestive and respiratory problems.
What Is the Scientific Evidence for Aromatherapy?
There is a major difficulty in studying aromatherapy by inhalation: how to conduct a double-blind, placebo-controlled trial. For the results of a study to be truly reliable, both participants and researchers must be kept in the dark regarding participants who received real treatment and who received placebo. (For more information on why this is so crucial, see
Why Does This Database Depend on Double-blind Studies?
.) Although it may be possible to keep researchers in the dark regarding which group is which, participants will certainly be aware of whether they smell something or not! This is a problem because it has been shown that when researchers create expectations about the effects of certain aromas, those effects may occur simply because of those expectations.
In other studies, researchers tricked participants in the control group and told them that they might be receiving an active but odorless treatment, when in fact they were simply given an inactive treatment without much in it. Still other studies managed to find ethical ways of keeping their study participants in the dark regarding whether they were enrolled in a study at all, and then introduced the odors surreptitiously. Partially effective compromises such as these are necessary. Unfortunately, most published studies on aromatherapy fail even to achieve this level of rigor, falling far below minimal scientific standards of reliability.
Thus, everything written below about true aromatherapy—that is, inhalation of an aroma—must be taken with a grain of salt.
These problems do not arise to the same extent in studies of essential oils taken by mouth or applied directly to the skin.
Inhalation of Essential Oils
Preliminary controlled trials suggest that various forms of aromatherapy might be helpful for calming people with
Several relatively poorly designed studies hint that aromatherapy combined with
One study evaluated the effects of
A controlled study suggests that inhalation of black pepper vapor may reduce the craving for cigarettes.
A topical ointment known as Tiger Balm has also shown promise for headaches. Tiger Balm contains camphor, menthol, cajaput, and clove oil. A double-blind study enrolling 57 people with acute tension headache compared the application of Tiger Balm to the forehead against placebo ointment as well as the drug acetaminophen (Tylenol).
Inhaled peppermint oil may also be helpful for relieving mucus congestion of the lungs and sinuses; however, there is only weak supporting evidence for this use.
In one study, abdominal massage with lavender, rose, and clary sage reduced
Controlled studies have evaluated proprietary-inhaled aromatherapy preparations for treating the
Oral Use of Essential Oils
Most, though not all, double-blind studies, some of which were quite large, indicate that oral use of essential oil monoterpenes can help
A double-blind, placebo-controlled study of 39 people found that an enteric-coated peppermint-
A preparation of peppermint, caraway, fennel, and
Other Oral Uses for Essential Oils
One study found preliminary evidence that a complicated mixture of essential oils (taken by gargle or mouth spray) might be helpful for reducing snoring symptoms.
A thorough review of 11 randomized, controlled trials found that the use of mouth rinses containing essential oils is effective against
Topical Use of Essential Oils
Topical essential oils might be helpful for
One study in rats indicates that under some circumstances essential oils instilled into the ear may be able to penetrate the eardrum.
Finally, for literally hundreds of essential oils,
How Might Aromatherapy Work?
It’s not clear how inhaled aromatherapy works (assuming that it does). Possibly, enough is inhaled through the lungs to produce meaningful concentrations of herbal chemicals in the body. It is also possible that aromatherapy might work through the olfactory centers of the brain. In other words, a pleasant fragrance may be soothing, refreshing, calming, and stimulating—hardly a revolutionary concept!
How to Choose an Aromatherapy Practitioner
For all intents and purposes, licensure in aromatherapy does not exist. For this reason, the best way to find a qualified practitioner is to seek a referral from a healthcare professional.
Essential oils can be toxic when taken internally, producing unpleasant and even fatal effects. Toxicity studies have not been performed for many essential oil products, and maximum safe dosages remain unknown. 36 Infants, children, seniors, and people with severe illnesses should not use essential oils internally except under the supervision of a physician; healthy adults should only use well established products (such as peppermint oil) for which safe dosages have been determined.
Inhaled or topical use of essential oils is much safer than oral use. However, allergic reactions to inhaled or topical plant fragrances are not uncommon.
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Last reviewed April 2009 by EBSCO CAM Review Board
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