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Aromatherapy and Essential Oils (PDQ®)
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- Summary of the Evidence for Aromatherapy and Essential Oils
- Changes to This Summary (10/16/2012)
- About This PDQ Summary
This complementary and alternative medicine (CAM) information summary provides an overview of the use of aromatherapy and essential oils primarily to improve the quality of life of cancer patients. This summary includes a brief history of aromatherapy, a review of laboratory studies and clinical trials, and possible adverse effects associated with aromatherapy use.
This summary contains the following key information:
- Aromatherapy is the therapeutic use of essential oils (also known as volatile oils) from plants (flowers, herbs, or trees) for the improvement of physical, emotional, and spiritual well-being.
- Aromatherapy is used by patients with cancer primarily as supportive care for general well-being.
- Aromatherapy is used with other complementary treatments (e.g., massage and acupuncture) as well as with standard treatment.
- Essential oils are volatile liquid substances extracted from aromatic plant material by steam distillation or mechanical expression; oils produced with the aid of chemical solvents are not considered true essential oils.
- Essential oils are available in the United States for inhalation and topical treatment. Topical treatments are generally used in diluted forms.
- Aromatherapy is not widely administered via ingestion.
- The effects of aromatherapy are theorized to result from the binding of chemical components in the essential oil to receptors in the olfactory bulb, impacting the brain’s emotional center, the limbic system. Topical application of aromatic oils may exert antibacterial, anti-inflammatory, and analgesic effects.
- Studies in animals show sedative and stimulant effects of specific essential oils as well as positive effects on behavior and the immune system. Functional imaging studies in humans support the influence of odors on the limbic system and its emotional pathways.
- Human clinical trials have investigated aromatherapy primarily in the treatment of stress and anxiety in patients with critical illnesses or in other hospitalized patients. Several clinical trials involving patients with cancer have been published.
- Aromatherapy has a relatively low toxicity profile when administered by inhalation or diluted topical application.
- Aromatherapy products are not subject to approval by the U.S. Food and Drug Administration unless there is a claim for treatment of specific diseases.
Many of the medical and scientific terms used in the summary are hypertext linked (at first use in each section) to the NCI Dictionary of Cancer Terms, which is oriented toward nonexperts. When a linked term is clicked, a definition will appear in a separate window.
Reference citations in some PDQ CAM information summaries may include links to external Web sites that are operated by individuals or organizations for the purpose of marketing or advocating the use of specific treatments or products. These reference citations are included for informational purposes only. Their inclusion should not be viewed as an endorsement of the content of the Web sites, or of any treatment or product, by the PDQ Cancer CAM Editorial Board or the National Cancer Institute.
Aromatherapy is a derivative of herbal medicine, which is itself a subset of the biological or nature-based complementary and alternative medicine (CAM) therapies. Aromatherapy has been defined as the therapeutic use of essential oils from plants for the improvement of physical, emotional, and spiritual well-being.
Essential oils are volatile liquid substances extracted from aromatic plant material by steam distillation or mechanical expression. Oils produced with the aid of chemical solvents are not considered true essential oils, because the solvent residues can alter the purity of the oils themselves and lead to adulteration of the fragrance or to skin irritation.
Essential oils are made up of a large array of chemical components that consist of the secondary metabolites found in various plant materials. The major chemical components of essential oils include terpenes, esters, aldehydes, ketones, alcohols, phenols, and oxides, which are volatile and may produce characteristic odors. Different types of oils contain varying amounts of each of these compounds, which are said to give each oil its particular fragrance and therapeutic characteristics. Different varieties of the same species may have different chemotypes (different chemical composition of the same plant species as a result of different harvesting methods or locations) and thus different types of effects.
Synthetic odors are often made up of many of the same compounds, which are synthesized and combined with other novel odor-producing chemicals. Most aromatherapists believe that synthetic fragrances are inferior to essential oils because they lack natural or vital energy; however, this has been contested by odor psychologists and biochemists.
Aromatherapy is used or claimed to be useful for a vast array of symptoms and conditions. A book on aromatherapy in children suggests aromatherapy remedies for everything from acne to whooping cough. Published studies regarding the uses of aromatherapy have generally focused on its psychological effects (used as a stress reliever or anxiolytic agent) or its use as a topical treatment for skin-related conditions.
A large body of literature has been published on the effects of odors on the human brain and emotions. Some studies have tested the effects of essential oils on mood, alertness, and mental stress in healthy subjects. Other studies investigated the effects of various (usually synthetic) odors on task performance, reaction time, and autonomic parameters or evaluated the direct effects of odors on the brain via electroencephalogram patterns and functional imaging studies. Such studies have consistently shown that odors can produce specific effects on human neuropsychological and autonomic function and that odors can influence mood, perceived health, and arousal. These studies suggest that odors may have therapeutic applications in the context of stressful and adverse psychological conditions.
Practitioners of aromatherapy apply essential oils using several different methods, including (1) indirect inhalation via a room diffuser or drops of oil placed near the patient (e.g., on a tissue), (2) direct inhalation used in an individual inhaler (e.g., a few drops of essential oil floated on top of hot water to aid a sinus headache), or (3) aromatherapy massage, which is the application to the body of essential oils diluted in a carrier oil. Other direct and indirect applications include mixing essential oils in bath salts and lotions or applying them to dressings. Different aromatherapy practitioners may have different recipes for treating specific conditions, involving various combinations of oils and methods of application. Differences seem to be practitioner-dependent, with some common uses more accepted throughout the aromatherapy community. Training and certification in aromatherapy for lay practitioners is available at several schools throughout the United States and United Kingdom, but there is no professional standardization in the United States, and no license is required to practice in either country. Thus, there is little consistency in the specific treatments used for specific illnesses among practitioners. This lack of standardization has led to poor consistency in research on the effects of aromatherapy, because anecdotal evidence alone or previous experience has driven the choice of oils, and different researchers often choose different oils when studying the same applications. However, there are now specific courses for licensed health professionals that give nursing or continuing medical education contact hours, including a small research component and information on evaluating/measuring outcomes.
The National Association for Holistic Aromatherapy (NAHA) (www.naha.org/) and the Alliance of International Aromatherapists (www.alliance-aromatherapists.org) are the two governing bodies for national educational standards for aromatherapists. NAHA is taking steps toward standardizing aromatherapy certification in the United States. Many schools offer certificate programs approved by NAHA. A list of these schools can be found on the NAHA Web site (www.naha.org/schools_level_one_two.htm). National examinations in aromatherapy are held twice per year.
The Canadian Federation of Aromatherapists has established standards for aromatherapy certification in Canada (www.cfacanada.com/). They also have standards for safety and professional conduct and a public directory of certified aromatherapists. Other countries may have similar organizations.
Although essential oils are given orally or internally by aromatherapists in France and Germany, use is generally limited to inhalation or topical application in the United Kingdom and United States. Nonmedical use of essential oils is common in the flavoring and fragrance industries. Most essential oils have been classified as GRAS (generally recognized as safe), at specified concentration limits, by the U.S. Food and Drug Administration (FDA). (See the International Federation of Aromatherapists [www.ifaroma.org/] for a list of international aromatherapy programs.)
Aromatherapy products do not need approval by the FDA.1Wildwood C: The Encyclopedia of Aromatherapy. Rochester, Vt: Healing Arts Press, 1996.2Dodd GH: The molecular dimension in perfumery. In: Van Toller S, Dodd GH, eds.: Perfumery: The Psychology and Biology of Fragrance. New York, NY: Chapman and Hall, 1988, pp 19-46.3Worwood VA: Aromatherapy for the Healthy Child: More Than 300 Natural, Non-Toxic, and Fragrant Essential Oil Blends. Novato, Calif: New World Library, 2000.4Buchbauer G, Jirovetz L, Jäger W, et al.: Fragrance compounds and essential oils with sedative effects upon inhalation. J Pharm Sci 82 (6): 660-4, 1993.
Proponents of aromatherapy report that aromatic or essential oils have been used for thousands of years as stimulants or sedatives of the nervous system and as treatments for a wide range of other disorders. They link it historically to the use of infused oils and unguents in the Bible and ancient Egypt, remedies used throughout the Middle Ages and the Renaissance, and the burning of aromatic plants in various religious rites. The current applications of aromatherapy did not come about until the early 20th century when the French chemist and perfumer Rene Gattefosse coined the term “aromatherapy” and published a book of that name in 1937. Gattefosse proposed the use of aromatherapy to treat diseases in virtually every organ system, citing mostly anecdotal and case-based evidence.
Although Gattefosse and his colleagues in France, Italy, and Germany studied the effects of aromatherapy for some 30 years, its use went out of fashion midcentury and was rediscovered by another Frenchman, a physician, Jean Valnet, in the latter part of the century. Valnet published his book The Practice of Aromatherapy in 1982, at which time the practice became more well-known in Britain and the United States. Through the 1980s and 1990s, as patients in Western countries became increasingly interested in complementary and alternative medicine (CAM) treatments, aromatherapy developed a following that continues to this day. In addition to the growing use of essential oils by nurses and aromatherapy practitioners for specific medical issues, the popularity of aromatherapy has also been exploited by cosmetics companies that have created lines of essential oil-based (though often with a synthetic component) cosmetics and toiletries, claiming to improve mood and well-being in their users.
Despite the growing popularity of aromatherapy in the latter part of the 20th century (especially in the United Kingdom), little research on aromatherapy was available in the English-language medical literature until the early or mid-1990s. The research that began to appear in the 1990s was most often conducted by nurses, who tended to be the primary practitioners of aromatherapy in the United States and United Kingdom (although it is dispensed by medical doctors in France and Germany). Aromatherapists now publish their own journal, the International Journal of Essential Oil Therapeutics. Also, many studies regarding the effects of odor on the brain and other systems in animals and healthy humans have been published in the context of odor psychology and neurobiology (and in the absence of the specific term aromatherapy).
In addition to topical antimicrobial uses, aromatherapy has also been proposed for use in wound care  and to treat a variety of localized symptoms and illnesses such as alopecia, eczema, and pruritus. Aromatherapy has also been studied via inhalation for airway reactivity.
Studies on aromatherapy have examined a variety of other conditions: sedation and arousal; startle reflex and reaction time; psychological states such as mood, anxiety, and general sense of well-being; psychiatric disorders; neurologic impairment; chronic renal failure; agitation in patients with dementia; smoking withdrawal symptoms; motion sickness; postoperative nausea; nausea and emesis in combination with fatigue, pain, and anxiety in patients in labor; pain alone; and pain in combination with other symptoms.
Published articles have described the use of aromatherapy in specific hospital settings such as cancer wards, hospices, and other areas where patients are critically ill and require palliative care for pain, nausea, lymphedema, generalized stress, anxiety, and depression. These observational studies provide examples of the clinical uses of aromatherapy (and other CAM modalities), though they are generally not evidence-based. Subjects have included hospitalized children with HIV, homebound patients with terminal disease, and hospitalized patients with leukemia. Aromatherapy has also been used to reduce malodor of necrotic ulcers in cancer patients.
Studies of aromatherapy use with mental health patients have also been conducted. Most of the resulting articles describe successful incorporation of aromatherapy into the treatment of these patients, though outcomes are clearly subjective.
Theories about the mechanism of action of aromatherapy and essential oils differ, depending on the community studying them. Proponents of aromatherapy often cite the connection between olfaction and the limbic system in the brain as the basis for the effects of aromatherapy on mood and emotions; less is said about proposed mechanisms for its effects on other parts of the body. Most of the aromatherapy literature, however, lacks in-depth neurophysiological studies on the nature of olfaction and its link to the limbic system, and it generally does not cite research that shows these links. Proponents of aromatherapy also believe that the effects of the treatments are based on the special nature of the essential oils used and that essential oils produce effects on the body that are greater than the sum of the individual chemical components of the scents.
These assertions have been contested by the biochemistry and psychology communities, which take a different view of the possible mechanism of action of odors on the human brain (most do not differentiate the odors produced by essential oils from those of synthetic fragrances). This neurobiological view, which focuses mostly on the emotional and psychological effects of fragrances (as opposed to the other symptomatic effects claimed by aromatherapists), takes into account what is known about olfactory transduction and the connection of the olfactory system to other central nervous system functions, including memory; however, it is primarily theoretical because of the lack of significant research addressing this topic.1Tisserand R: Essential oils as psychotherapeutic agents. In: Van Toller S, Dodd GH, eds.: Perfumery: The Psychology and Biology of Fragrance. New York, NY: Chapman and Hall, 1988, pp 167-80.2Gattefosse RM: Gattefosse's Aromatherapy. Essex, England:CW Daniel, 1993.3Valnet J: The Practice of Aromatherapy: A Classic Compendium of Plant Medicines & Their Healing Properties. Rochester, NY: Healing Arts Press, 1990.4Hartman D, Coetzee JC: Two US practitioners' experience of using essential oils for wound care. J Wound Care 11 (8): 317-20, 2002.5Asquith S: The use of aromatherapy in wound care. J Wound Care 8 (6): 318-20, 1999.6Edwards-Jones V, Buck R, Shawcross SG, et al.: The effect of essential oils on methicillin-resistant Staphylococcus aureus using a dressing model. Burns 30 (8): 772-7, 2004.7Hay IC, Jamieson M, Ormerod AD: Randomized trial of aromatherapy. Successful treatment for alopecia areata. Arch Dermatol 134 (11): 1349-52, 1998.8Anderson C, Lis-Balchin M, Kirk-Smith M: Evaluation of massage with essential oils on childhood atopic eczema. Phytother Res 14 (6): 452-6, 2000.9Ro YJ, Ha HC, Kim CG, et al.: The effects of aromatherapy on pruritus in patients undergoing hemodialysis. Dermatol Nurs 14 (4): 231-4, 237-8, 256; quiz 239, 2002.10Cohen BM, Dressler WE: Acute aromatics inhalation modifies the airways. Effects of the common cold. Respiration 43 (4): 285-93, 1982.11Diego MA, Jones NA, Field T, et al.: Aromatherapy positively affects mood, EEG patterns of alertness and math computations. Int J Neurosci 96 (3-4): 217-24, 1998.12Motomura N, Sakurai A, Yotsuya Y: Reduction of mental stress with lavender odorant. Percept Mot Skills 93 (3): 713-8, 2001.13Miltner W, Matjak M, Braun C, et al.: Emotional qualities of odors and their influence on the startle reflex in humans. Psychophysiology 31 (1): 107-10, 1994.14Millot JL, Brand G, Morand N: Effects of ambient odors on reaction time in humans. Neurosci Lett 322 (2): 79-82, 2002.15Stevenson C: Measuring the effects of aromatherapy. Nurs Times 88 (41): 62-3, 1992 Oct 7-13.16Dunn C, Sleep J, Collett D: Sensing an improvement: an experimental study to evaluate the use of aromatherapy, massage and periods of rest in an intensive care unit. J Adv Nurs 21 (1): 34-40, 1995.17Buckle J: Aromatherapy. Nurs Times 89 (20): 32-5, 1993 May 19-25.18Hadfield N: The role of aromatherapy massage in reducing anxiety in patients with malignant brain tumours. Int J Palliat Nurs 7 (6): 279-85, 2001.19Wilkinson S: Aromatherapy and massage in palliative care. Int J Palliat Nurs 1 (1): 21-30, 1995.20Wilkinson S, Aldridge J, Salmon I, et al.: An evaluation of aromatherapy massage in palliative care. Palliat Med 13 (5): 409-17, 1999.21Corner J, Cawler N, Hildebrand S: An evaluation of the use of massage and essential oils on the wellbeing of cancer patients. Int J Palliat Nurs 1 (2): 67-73, 1995.22Louis M, Kowalski SD: Use of aromatherapy with hospice patients to decrease pain, anxiety, and depression and to promote an increased sense of well-being. Am J Hosp Palliat Care 19 (6): 381-6, 2002 Nov-Dec.23Walsh E, Wilson C: Complementary therapies in long-stay neurology in-patient settings. Nurs Stand 13 (32): 32-5, 1999 Apr 28-May 4.24Itai T, Amayasu H, Kuribayashi M, et al.: Psychological effects of aromatherapy on chronic hemodialysis patients. Psychiatry Clin Neurosci 54 (4): 393-7, 2000.25Burns E, Blamey C: Complementary medicine. Using aromatherapy in childbirth. Nurs Times 90 (9): 54-60, 1994 Mar 2-8.26Burns EE, Blamey C, Ersser SJ, et al.: An investigation into the use of aromatherapy in intrapartum midwifery practice. J Altern Complement Med 6 (2): 141-7, 2000.27Kite SM, Maher EJ, Anderson K, et al.: Development of an aromatherapy service at a Cancer Centre. Palliat Med 12 (3): 171-80, 1998.28Komori T, Fujiwara R, Tanida M, et al.: Effects of citrus fragrance on immune function and depressive states. Neuroimmunomodulation 2 (3): 174-80, 1995 May-Jun.29Wiebe E: A randomized trial of aromatherapy to reduce anxiety before abortion. Eff Clin Pract 3 (4): 166-9, 2000 Jul-Aug.30Perry N, Perry E: Aromatherapy in the management of psychiatric disorders: clinical and neuropharmacological perspectives. CNS Drugs 20 (4): 257-80, 2006.31Ballard CG, O'Brien JT, Reichelt K, et al.: Aromatherapy as a safe and effective treatment for the management of agitation in severe dementia: the results of a double-blind, placebo-controlled trial with Melissa. J Clin Psychiatry 63 (7): 553-8, 2002.32Smallwood J, Brown R, Coulter F, et al.: Aromatherapy and behaviour disturbances in dementia: a randomized controlled trial. Int J Geriatr Psychiatry 16 (10): 1010-3, 2001.33Holmes C, Hopkins V, Hensford C, et al.: Lavender oil as a treatment for agitated behaviour in severe dementia: a placebo controlled study. Int J Geriatr Psychiatry 17 (4): 305-8, 2002.34Gray SG, Clair AA: Influence of aromatherapy on medication administration to residential-care residents with dementia and behavioral challenges. Am J Alzheimers Dis Other Demen 17 (3): 169-74, 2002 May-Jun.35Snow LA, Hovanec L, Brandt J: A controlled trial of aromatherapy for agitation in nursing home patients with dementia. J Altern Complement Med 10 (3): 431-7, 2004.36Rose JE, Behm FM: Inhalation of vapor from black pepper extract reduces smoking withdrawal symptoms. Drug Alcohol Depend 34 (3): 225-9, 1994.37Sayette MA, Parrott DJ: Effects of olfactory stimuli on urge reduction in smokers. Exp Clin Psychopharmacol 7 (2): 151-9, 1999.38Post-White N, Nichols W: Randomized trial testing of QueaseEase™ essential oil for motion sickness. International Journal of Essential Oil Therapeutics 1 (4): 158-66, 2007.39Tate S: Peppermint oil: a treatment for postoperative nausea. J Adv Nurs 26 (3): 543-9, 1997.40Hines S, Steels E, Chang A, et al.: Aromatherapy for treatment of postoperative nausea and vomiting. Cochrane Database Syst Rev 4: CD007598, 2012.41Oyama H, Kaneda M, Katsumata N, et al.: Using the bedside wellness system during chemotherapy decreases fatigue and emesis in cancer patients. J Med Syst 24 (3): 173-82, 2000.42Dale A, Cornwell S: The role of lavender oil in relieving perineal discomfort following childbirth: a blind randomized clinical trial. J Adv Nurs 19 (1): 89-96, 1994.43Göbel H, Schmidt G, Soyka D: Effect of peppermint and eucalyptus oil preparations on neurophysiological and experimental algesimetric headache parameters. Cephalalgia 14 (3): 228-34; discussion 182, 1994.44Marchand S, Arsenault P: Odors modulate pain perception: a gender-specific effect. Physiol Behav 76 (2): 251-6, 2002.45Kim JT, Wajda M, Cuff G, et al.: Evaluation of aromatherapy in treating postoperative pain: pilot study. Pain Pract 6 (4): 273-7, 2006.46Barclay J, Vestey J, Lambert A, et al.: Reducing the symptoms of lymphoedema: is there a role for aromatherapy? Eur J Oncol Nurs 10 (2): 140-9, 2006.47Kohara H, Miyauchi T, Suehiro Y, et al.: Combined modality treatment of aromatherapy, footsoak, and reflexology relieves fatigue in patients with cancer. J Palliat Med 7 (6): 791-6, 2004.48Buckle J: Clinical Aromatherapy: Essential Oils in Practice. 2nd ed. New York, NY: Churchill Livingston, 2003.49Wilkinson SM, Love SB, Westcombe AM, et al.: Effectiveness of aromatherapy massage in the management of anxiety and depression in patients with cancer: a multicenter randomized controlled trial. J Clin Oncol 25 (5): 532-9, 2007.50Styles JL: The use of aromatherapy in hospitalized children with HIV disease. Complement Ther Nurs Midwifery 3 (1): 16-20, 1997.51Rimmer L: The clinical use of aromatherapy in the reduction of stress. Home Healthc Nurse 16 (2): 123-6, 1998.52Stringer J: Massage and aromatherapy on a leukaemia unit. Complement Ther Nurs Midwifery 6 (2): 72-6, 2000.53Warnke PH, Sherry E, Russo PA, et al.: Antibacterial essential oils in malodorous cancer patients: clinical observations in 30 patients. Phytomedicine 13 (7): 463-7, 2006.54Hicks G: Aromatherapy as an adjunct to care in a mental health day hospital. J Psychiatr Ment Health Nurs 5 (4): 317, 1998.
Numerous studies on the topical antibacterial effects of essential oils have been published; most have found the oils to have significant antimicrobial activity. Some essential oils are antiviral and inhibit replication of the herpes simplex virus. Other essential oils are fungistatic and fungicidal against both vaginal and oropharyngeal Candida albicans.
Studies on rats in Europe and Japan have shown that exposure to various odors can result in stimulation or sedation, as well as changes in behavioral responses to stress and pain. A study  on the sedative effects of essential oils and other fragrance compounds (mostly individual chemical components of the oils) on rat motility showed that lavender oil (Lavandula angustifolia Miller [synonyms: Lavandula spicata L.; Lavandula vera DC.]) in particular had a significant sedative effect, and several single-oil constituents (as opposed to whole essential oils) had similarly strong effects. The authors do not comment on the presumed mechanism for this effect, though they suggest that the difference in results between the different oils (some of which were found to be stimulating, some sedative) is related to the “different chemical structures of the compounds…and functional groups…indicating the essential role of the volatility of the fragrance compounds and its bioavailability." The differences in bioavailability are ascribed to different levels of lipophilia, with the more lipophilic oils producing the most sedative effects. The researchers also found significant plasma levels of the fragrance compounds after inhalation, suggesting that the effects of aromatherapy result from a direct pharmacological interaction rather than an indirect central nervous system relay.
Other studies have investigated the effects of aromatherapy on rats’ behavioral and immunological responses to painful, stressful, or startling stimuli. In two European studies, rats exposed to pleasant odors during painful stimuli exhibited decreased pain-related behaviors, with some variation in response between the sexes. Two studies from Japan showed an improvement in immunological and behavioral markers in rats exposed to fragrances while under stressful conditions.1Aridoğan BC, Baydar H, Kaya S, et al.: Antimicrobial activity and chemical composition of some essential oils. Arch Pharm Res 25 (6): 860-4, 2002.2Minami M, Kita M, Nakaya T, et al.: The inhibitory effect of essential oils on herpes simplex virus type-1 replication in vitro. Microbiol Immunol 47 (9): 681-4, 2003.3D'Auria FD, Tecca M, Strippoli V, et al.: Antifungal activity of Lavandula angustifolia essential oil against Candida albicans yeast and mycelial form. Med Mycol 43 (5): 391-6, 2005.4Buchbauer G, Jirovetz L, Jäger W, et al.: Fragrance compounds and essential oils with sedative effects upon inhalation. J Pharm Sci 82 (6): 660-4, 1993.5Aloisi AM, Ceccarelli I, Masi F, et al.: Effects of the essential oil from citrus lemon in male and female rats exposed to a persistent painful stimulation. Behav Brain Res 136 (1): 127-35, 2002.6Jahangeer AC, Mellier D, Caston J: Influence of olfactory stimulation on nociceptive behavior in mice. Physiol Behav 62 (2): 359-66, 1997.7Shibata H, Fujiwara R, Iwamoto M, et al.: Immunological and behavioral effects of fragrance in mice. Int J Neurosci 57 (1-2): 151-9, 1991.8Fujiwara R, Komori T, Noda Y, et al.: Effects of a long-term inhalation of fragrances on the stress-induced immunosuppression in mice. Neuroimmunomodulation 5 (6): 318-22, 1998 Nov-Dec.
No studies in the published peer-reviewed literature discuss aromatherapy as a treatment for people with cancer. The studies discussed below, most of which were conducted in patients with cancer, primarily focus on other health-related conditions and on quality of life measures such as stress and anxiety levels.
A major review published in 2000  focused on six studies investigating treatment or prevention of anxiety with aromatherapy massage. Although the studies suggested that aromatherapy massage had a mild transient anxiolytic effect, the authors concluded that the research done at that time was not sufficiently rigorous or consistent to prove the effectiveness of aromatherapy in treating anxiety. This review excluded trials related to other effects of aromatherapy (such as pain control) and did not include any studies looking at the effects of odors that were not specifically labeled as aromatherapy.
Several of the studies included in the Cochrane Database of Systematic Reviews are discussed in more detail. A randomized controlled pilot study examined the effects of adjunctive aromatherapy massage on mood, quality of life, and physical symptoms in patients with cancer. Forty-six patients were randomly assigned to conventional day care alone or day care plus weekly aromatherapy massage using a standardized blend of oils (1% lavender and chamomile in sweet almond carrier oil) for 4 weeks. Patients self-rated their mood, quality of life, and the intensity of the two symptoms that were the most concerning to them at the beginning of the study and at weekly intervals thereafter. Of the 46 patients, only 11 of 23 (48%) in the aromatherapy group and 18 of 23 (78%) in the control group completed all of the 4 weeks. Patient-reported mood, symptoms, and quality of life improved in both groups, and there was no statistically significant difference between the two groups in any of these measures.
Another randomized controlled trial examined the effects of aromatherapy massage and massage alone on 42 patients with advanced cancer over a 4-week period. Patients were randomly assigned to receive weekly massages with or without aromatherapy; the treatment group (aromatherapy group) received massages with lavender essential oil (Lavandula angustifolia Miller [synonyms: Lavandula spicata L.; Lavandula vera DC.]) and an inert carrier oil, and the control group (massage group) received either an inert carrier oil alone or no intervention. The authors reported no significant long-term benefits of aromatherapy or massage in pain control, quality of life, or anxiety, but sleep scores (as measured by the Verran and Snyder-Halpern sleep scale) improved significantly in both groups. The authors also reported statistically significant reductions in depression scores (as measured by the Hospital Anxiety and Depression Scale [HADS]) in the massage-only group.
A placebo-controlled, double-blind, randomized trial conducted in Australia investigated the effects of inhalation aromatherapy on anxiety during radiation therapy. A total of 313 patients receiving radiation therapy were randomly assigned to one of three groups: carrier oil with fractionated oils, carrier oil only, or pure essential oils of lavender, bergamot (Citrus aurantium L. ssp. bergamia [Risso] Wright & Arn. [Rutaceae]; [synonym: Citrus bergamia Risso]), and cedarwood (Cedrus atlantica [Endl.] Manetti ex Carriere [Pinaceae]). All three groups received the oils by inhalation during their radiation therapy. The authors reported no significant differences in depression (as measured by HADS) or psychological effects (as measured by the Somatic and Psychological Health Report) between the groups. The group that received only the carrier oil showed a statistically significant decrease in anxiety (as measured by HADS) compared with the other two groups.
Another randomized controlled trial investigated the effects of massage or aromatherapy massage in 103 cancer patients who were randomly assigned to receive massage using a carrier oil (massage group) or massage using a carrier oil plus the Roman chamomile essential oil (Chamaemelum nobile [L.] All. [synonym: Anthemis nobilis L.]) (aromatherapy massage group). Two weeks after the massage, the authors found a statistically significant reduction in anxiety in the aromatherapy massage group (as measured by the State-Trait Anxiety Inventory) and an improvement in symptoms (as measured by the Rotterdam Symptom Checklist [RSCL]; the subscales with improved scores were psychological, quality of life, severe physical, and severe psychological). The authors reported that the massage-only group showed improvement on four RSCL subscales; however, these improvements did not reach statistical significance.
In a placebo-controlled, double-blind, randomized trial of bergamot inhalation aromatherapy compared with a pleasant smelling shampoo that did not contain essential oils, administered at the time of stem cell infusion in 37 children and adolescents undergoing stem cell transplant, aromatherapy was not found to be beneficial in reducing nausea, anxiety, or pain. As administered in this study, bergamot inhalation aromatherapy may have contributed to persistent anxiety following the infusion of stem cells. Although no more effective than placebo, parents receiving aromatherapy showed a significant decrease in their transitory anxiety during the period between the completion of their child’s infusion and 1 hour following infusion. Nausea and pain subsided over the course of the intervention for all children, though nausea remained significantly greater in patients receiving aromatherapy. These findings suggest that the diffusion of bergamot essential oil may not provide suitable anxiolytic and antiemetic effects among children and adolescents undergoing stem cell transplantation. The double blinding of the trial may explain the results, as single-blinded or nonblinded trials in general supported the aromatherapy intervention.
A similar study evaluated the efficacy of an aromatherapy intervention for reduction of symptom intensity of nausea, retching, and/or coughing among adult patients receiving stem cells preserved in dimethyl sulfoxide. The study found that an intervention of tasting or sniffing sliced oranges was more effective at reducing symptom intensity than an orange essential oil inhalation aromatherapy.
A study whose primary objective was evaluating an aromatherapy service following changes made after an initial pilot at a U.K. cancer center also reported on the experiences of patients referred to the service. Of 89 patients originally referred, 58 completed six aromatherapy sessions. The authors reported significant improvements in anxiety and depression (as measured by HADS) at the completion of the six sessions, as compared with before the six sessions. A small study examined the physical and psychological effects of aromatherapy massage in eight patients with primary malignant brain tumors attending their first follow-up appointment after radiation therapy. The author reported no psychological benefit in these patients from aromatherapy massage (as measured by HADS) but reported a statistically significant reduction in blood pressure, pulse, and respiratory rate.
Antibiotic-resistant bacteria, such as methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococcus, are an increasing problem worldwide, causing intractable wound infections. Phytochemical mixtures, such as constituents of the volatile oils of lemongrass, eucalyptus, melaleuca, clove, and thyme with butylated hydroxytoluene, triclosan (0.3%), and 95% undenatured ethanol (69.7%), are being investigated against MRSA in vitro. No clinical trials have been performed.
Two topical MRSA eradication regimens were compared in hospital patients. A standard treatment, which included mupirocin 2% nasal ointment, chlorhexidine gluconate 4% soap, and silver sulfadiazine 1% cream was given versus a tea tree oil regimen (melaleuca), which included tea tree 10% cream and tea tree 5% body wash. Both were administered for 5 days. One hundred fourteen patients received the standard treatment, and 56 (49%) were cleared of MRSA carriage. One hundred ten patients received the tea tree oil regimen, and 46 (41%) were cleared of MRSA carriage. In a small group of patients, the tea tree oil regimen was associated with a higher clearance rate of MRSA carriage in the axilla, groin, and wound sites, but the difference versus standard treatment was not significant.
Current Clinical Trials
Check NCI’s list of cancer clinical trials for cancer CAM clinical trials on aromatherapy and essential oils that are actively enrolling patients.
General information about clinical trials is also available from the NCI Web site.1Cooke B, Ernst E: Aromatherapy: a systematic review. Br J Gen Pract 50 (455): 493-6, 2000.2Wilcock A, Manderson C, Weller R, et al.: Does aromatherapy massage benefit patients with cancer attending a specialist palliative care day centre? Palliat Med 18 (4): 287-90, 2004.3Soden K, Vincent K, Craske S, et al.: A randomized controlled trial of aromatherapy massage in a hospice setting. Palliat Med 18 (2): 87-92, 2004.4Graham PH, Browne L, Cox H, et al.: Inhalation aromatherapy during radiotherapy: results of a placebo-controlled double-blind randomized trial. J Clin Oncol 21 (12): 2372-6, 2003.5Wilkinson S, Aldridge J, Salmon I, et al.: An evaluation of aromatherapy massage in palliative care. Palliat Med 13 (5): 409-17, 1999.6Ndao DH, Ladas EJ, Cheng B, et al.: Inhalation aromatherapy in children and adolescents undergoing stem cell infusion: results of a placebo-controlled double-blind trial. Psychooncology 21 (3): 247-54, 2012.7Potter P, Eisenberg S, Cain KC, et al.: Orange interventions for symptoms associated with dimethyl sulfoxide during stem cell reinfusions: a feasibility study. Cancer Nurs 34 (5): 361-8, 2011 Sep-Oct.8Kite SM, Maher EJ, Anderson K, et al.: Development of an aromatherapy service at a Cancer Centre. Palliat Med 12 (3): 171-80, 1998.9Hadfield N: The role of aromatherapy massage in reducing anxiety in patients with malignant brain tumours. Int J Palliat Nurs 7 (6): 279-85, 2001.10Sherry E, Boeck H, Warnke PH: Percutaneous treatment of chronic MRSA osteomyelitis with a novel plant-derived antiseptic. BMC Surg 1: 1, 2001.11Dryden MS, Dailly S, Crouch M: A randomized, controlled trial of tea tree topical preparations versus a standard topical regimen for the clearance of MRSA colonization. J Hosp Infect 56 (4): 283-6, 2004.
Safety testing on essential oils has shown minimal adverse effects. Several oils have been approved for use as food additives and are classified as GRAS (generally recognized as safe) by the U.S. Food and Drug Administration; however, ingestion of large amounts of essential oils is not recommended. In addition, a few cases of contact dermatitis have been reported, mostly in aromatherapists who have had prolonged skin contact with oils in the context of aromatherapy massage. Some essential oils (e.g., camphor oil) can cause local irritation; therefore, care should be taken when applying them. Phototoxicity has occurred when essential oils (particularly citrus oils) are applied directly to the skin before sun exposure. One case report also showed airborne contact dermatitis in the context of inhaled aromatherapy without massage. Often, aromatherapy uses undefined mixtures of essential oils without specifying the plant sources. Allergic reactions are sometimes reported, especially following topical administration. As essential oils age, they are often oxidized so the chemical composition changes. Individual psychological associations with odors may result in adverse responses. Repeated exposure to lavender and tea tree oils by topical administration was shown in one study to be associated with reversible prepubertal gynecomastia. The effects appear to have been caused by the purported weak estrogenic and antiandrogenic activities of lavender and tea tree oils. Therefore, avoiding these two essential oils is recommended in patients with estrogen-dependant tumors. However, this is the first published report of this type of adverse effect when using products containing tea tree or lavender oils.1Bilsland D, Strong A: Allergic contact dermatitis from the essential oil of French marigold (Tagetes patula) in an aromatherapist. Contact Dermatitis 23 (1): 55-6, 1990.2Schaller M, Korting HC: Allergic airborne contact dermatitis from essential oils used in aromatherapy. Clin Exp Dermatol 20 (2): 143-5, 1995.3Henley DV, Lipson N, Korach KS, et al.: Prepubertal gynecomastia linked to lavender and tea tree oils. N Engl J Med 356 (5): 479-85, 2007.
Summary of the Evidence for Aromatherapy and Essential Oils
To assist readers in evaluating the results of human studies of complementary and alternative medicine (CAM) treatments for people with cancer, the strength of the evidence (i.e., the levels of evidence) associated with each type of treatment is provided whenever possible. To qualify for a level of evidence analysis, a study must:
- Be published in a peer-reviewed scientific journal.
- Report on a therapeutic outcome or outcomes, such as tumor response, improvement in survival, or measured improvement in quality of life.
- Describe clinical findings in enough detail that a meaningful evaluation can be made.
Separate levels of evidence scores are assigned to qualifying human studies on the basis of statistical strength of the study design and scientific strength of the treatment outcomes (i.e., endpoints) measured. The resulting two scores are then combined to produce an overall score. A table showing the levels of evidence scores for qualifying human studies cited in this summary is presented below. For an explanation of the scores and additional information about levels of evidence analysis of CAM treatments for people with cancer, refer to Levels of Evidence for Human Studies of Cancer Complementary and Alternative Medicine.Use of Aromatherapy as a Supportive Care Agent in Cancer and Palliative Care: Table of Clinical Studies Reference CitationsType of Study/Essential Oil/Mode of Administration No. of Patients Enrolled; Treated; ControlCondition InvestigatedPrimary OutcomeSecondary OutcomeLevel of Evidence ScoreNo. = number; QOL = quality of life.aPatients with cancer.bPatients with breast cancer undergoing bone marrow transplantation.cPatients with malignant brain tumors.dLavender (43%), rosewood (29%), rose (7%), and valerian (4%).Randomized nonblinded triala/lavender (Lavandula angustifolia Miller [synonyms: Lavandula spicata L.; Lavandula vera DC.]) and chamomile blend/massage46; 11; 18Mood, QOL, physical symptomsNo effect on mood, QOL, or physical symptomsNone1iiRandomized nonblinded triala/lavender/ massage42; 29; 13PainNo effect on painImproved sleep in both groups; reduced depression (in massage group); no effect on QOL1iiRandomized nonblinded triala/chamomile/massage103; 43; 44Physical and psychological symptoms, QOLReduction in anxiety and in physical and psychological symptoms; improved QOLNone1iiRandomized nonblinded triala/chamomile/massage52; 26; 25QOL, physical symptoms, anxietyImproved QOL, fewer physical symptoms, reduced anxietyNone1iiRandomized nonblinded triala/aromatherapy blendd/massage52; 34; 18Anxiety, mobilityDecreased anxiety, pain; improved mobilityNone1iiDouble-blind randomized control triala/lavender, bergamot (Citrus aurantium L. ssp. bergamia [Risso] Wright & Arn. [Rutaceae]; [synonym: Citrus bergamia Risso]), and cedarwood (Cedrus atlantica [Endl.] Manetti ex Carriere [Pinaceae])/indirect application313AnxietyNo effect on anxietyNo effect on depression or fatigue1iRandomized placebo-controlled double-blind trial/bergamot/ inhalation37; 17; 20Anxiety, nausea, pain in children undergoing stem cell transplantIncreased anxiety and nausea in children 1 hour after stem cell infusion in aromatherapy group; no effect on painParental anxiety declined in both groups1iCRandomized controlled single-blind trial/sweet orange/inhalation60; 23; 19; 18 (aromatherapy; orange tasting/sniffing; control)Symptom intensity (nausea, retching, cough)Greatest reduction in symptom intensity with orange tasting/sniffingNone1CRandomized single-blind trial/choice of 20 essential oils/massage39; 20; 19Feasibility; moodImprovements in mood in both groups (aromatherapy massage and cognitive behavioral therapy)Preference for aromatherapy over cognitive behavior therapy1CRandomized single-blind trial/choice of bitter orange, black pepper, rosemary, majoram, and patchouli/massage45; 15; 15; 15 (aromatherapy massage; plain massage; control)Constipation; QOLImprovement with aromatherapy massageImproved QOL1CNonrandomized controlled clinical trialb/lavender, eucalyptus (Eucalyptus globulus Labill. and Eucalyptus radiata Sieber ex DC. [Myrtaceae]), and tea tree/topical application16; 6; 10InfectionNo effect on incidence of infectionNone2Nonrandomized controlled clinical trialb/geranium (Pelargonium species), German chamomile (Matricaria recutita L. [synonyms: Matricaria chamomilla L., Chamomilla recutita (L.) Rausch.]), patchouli (Pogostemon cablin [Blanco] Benth. [Lamiaceae] [synonyms: Mentha cablin Blanco, Pogostemon patchouly Letettier]), and turmeric phytol/oral application48; 24; 24Gastrointestinal symptomsNo effect on gastrointestinal symptomsNone2Consecutive case seriesc/lavender or chamomile/massage18; 8Anxiety, depressionNo reduction in anxiety or depressionReduction in blood pressure, pulse, and respiration 3iiConsecutive casea/various oils/massage69General symptomsGeneral improvement in symptoms reported by patients; no statistical analysis completed None3ii 1Wilcock A, Manderson C, Weller R, et al.: Does aromatherapy massage benefit patients with cancer attending a specialist palliative care day centre? Palliat Med 18 (4): 287-90, 2004.2Soden K, Vincent K, Craske S, et al.: A randomized controlled trial of aromatherapy massage in a hospice setting. Palliat Med 18 (2): 87-92, 2004.3Wilkinson S, Aldridge J, Salmon I, et al.: An evaluation of aromatherapy massage in palliative care. Palliat Med 13 (5): 409-17, 1999.4Wilkinson S: Aromatherapy and massage in palliative care. Int J Palliat Nurs 1 (1): 21-30, 1995.5Corner J, Cawler N, Hildebrand S: An evaluation of the use of massage and essential oils on the wellbeing of cancer patients. Int J Palliat Nurs 1 (2): 67-73, 1995.6Graham PH, Browne L, Cox H, et al.: Inhalation aromatherapy during radiotherapy: results of a placebo-controlled double-blind randomized trial. J Clin Oncol 21 (12): 2372-6, 2003.7Ndao DH, Ladas EJ, Cheng B, et al.: Inhalation aromatherapy in children and adolescents undergoing stem cell infusion: results of a placebo-controlled double-blind trial. Psychooncology 21 (3): 247-54, 2012.8Potter P, Eisenberg S, Cain KC, et al.: Orange interventions for symptoms associated with dimethyl sulfoxide during stem cell reinfusions: a feasibility study. Cancer Nurs 34 (5): 361-8, 2011 Sep-Oct.9Serfaty M, Wilkinson S, Freeman C, et al.: The ToT study: helping with Touch or Talk (ToT): a pilot randomised controlled trial to examine the clinical effectiveness of aromatherapy massage versus cognitive behaviour therapy for emotional distress in patients in cancer/palliative care. Psychooncology 21 (5): 563-9, 2012.10Lai TK, Cheung MC, Lo CK, et al.: Effectiveness of aroma massage on advanced cancer patients with constipation: a pilot study. Complement Ther Clin Pract 17 (1): 37-43, 2011.11Gravett P: Aromatherapy treatment for patients with Hickman line infection following high-dose chemotherapy. International Journal of Aromatherapy 11 (1): 18-9, 2001.12Gravett P: Treatment of gastrointestinal upset following high-dose chemotherapy. International Journal of Aromatherapy 11 (2): 84-6, 2001.13Hadfield N: The role of aromatherapy massage in reducing anxiety in patients with malignant brain tumours. Int J Palliat Nurs 7 (6): 279-85, 2001.14Evans B: An audit into the effects of aromatherapy massage and the cancer patient in palliative and terminal care. Complement Ther Med 3 (4): 239-41, 1995.
Changes to This Summary (10/16/2012)
Revised text to state that the effects of aromatherapy are theorized to result from the binding of chemical components in the essential oil to receptors in the olfactory bulb, impacting the brain's emotional center, the limbic system.
Revised text to state that aromatherapy products are not subject to approval by the U.S. Food and Drug Administration unless there is a claim for treatment of specific diseases.
Revised text to state that there are now specific courses for licensed health professionals that give nursing or continuing medical education contact hours, including a small research component and information on evaluating/measuring outcomes.
Added Hines et al. as reference 40.
Revised text to state that the neurobiological view, which focuses mostly on the emotion and psychological effects of fragrances (as opposed to the other symptomatic effects claimed by aromatherapists), takes into account what is known about olfactory transduction and the connection of the olfactory system to other central nervous system functions, including memory; however, it is primarily theoretical because of the lack of significant research addressing this topic.
Revised text to state that 46 patients were randomly assigned to conventional day care alone or day care plus weekly aromatherapy massage using a standardized blend of oils (1% lavender and chamomile in sweet almond carrier oil) for 4 weeks.
Added Ndao et al. as reference 6.
Revised text to state that phytochemical mixtures, such as constituents of the volatile oils of lemongrass, eucalyptus, melaleuca, clove, and thyme with butylated hydroxytoluene, triclosan (0.3%), and 95% undenatured ethanol (69.7%), are being investigated against MRSA in vitro.
This summary is written and maintained by the PDQ Cancer Complementary and Alternative Medicine Editorial Board, which is editorially independent of NCI. The summary reflects an independent review of the literature and does not represent a policy statement of NCI or NIH. More information about summary policies and the role of the PDQ Editorial Boards in maintaining the PDQ summaries can be found on the About This PDQ Summary and PDQ NCI's Comprehensive Cancer Database pages.
About This PDQ Summary
Purpose of This Summary
This PDQ cancer information summary for health professionals provides comprehensive, peer-reviewed, evidence-based information about the use of aromatherapy and essential oils in the treatment of people with cancer. It is intended as a resource to inform and assist clinicians who care for cancer patients. It does not provide formal guidelines or recommendations for making health care decisions.
Reviewers and Updates
This summary is reviewed regularly and updated as necessary by the PDQ Cancer Complementary and Alternative Medicine Editorial Board, which is editorially independent of the National Cancer Institute (NCI). The summary reflects an independent review of the literature and does not represent a policy statement of NCI or the National Institutes of Health (NIH).
Board members review recently published articles each month to determine whether an article should:
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- be cited with text, or
- replace or update an existing article that is already cited.
Changes to the summaries are made through a consensus process in which Board members evaluate the strength of the evidence in the published articles and determine how the article should be included in the summary.
The lead reviewers for Aromatherapy and Essential Oils are:
- John A. Beutler, PhD (National Cancer Institute)
- Kara Kelly, MD (Columbia University)
- Elena Ladas, MS, RD (Columbia University)
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Levels of Evidence
Some of the reference citations in this summary are accompanied by a level-of-evidence designation. These designations are intended to help readers assess the strength of the evidence supporting the use of specific interventions or approaches. The PDQ Cancer Complementary and Alternative Medicine Editorial Board uses a formal evidence ranking system in developing its level-of-evidence designations.
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National Cancer Institute: PDQ® Aromatherapy and Essential Oils. Bethesda, MD: National Cancer Institute. Date last modified <MM/DD/YYYY>. Available at: http://www.cancer.gov/cancertopics/pdq/cam/aromatherapy/healthprofessional. Accessed <MM/DD/YYYY>.
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This information was last updated on 2012-10-16