Aromatherapy and Essential Oils (PDQ®): Complementary and alternative medicine - Health Professional Information [NCI]

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Aromatherapy and Essential Oils

Purpose of This PDQ Summary

This PDQcancer information summary for health professionals provides comprehensive, peer-reviewed, evidence-based information about the use of aromatherapy and essential oils as a treatment for cancer. The summary is reviewed regularly and updated as necessary by the PDQ Cancer Complementary and Alternative Medicine Editorial Board.

Information about the following is included in this summary:

  • A brief history of aromatherapy and essential oils research.
  • The results of clinical studies of aromatherapy and essential oils.
  • Possible side effects of aromatherapy and essential oils use.

This summary is intended as a resource to inform and assist clinicians and other health professionals who care for cancer patients. It does not provide formal guidelines or recommendations for making health care decisions.

Some of the reference citations in the summary are accompanied by a level of evidence designation. These designations are intended to help the readers assess the strength of the evidence supporting the use of specific interventions or treatment strategies. The PDQ Cancer Complementary and Alternative Medicine Editorial Board uses a formal evidence ranking system in developing its level of evidence designations. These designations should not be used as a basis for reimbursement determinations.

This summary is also available in a patient version, which is written in less technical language.

Overview

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 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 effect of odorantmolecules from essential oils on 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 do not need approval by the U.S. Food and Drug Administration because there is no claim for treatment of specific diseases.
  • Repeated exposure to lavender and tea tree oils by topical administration has been associated with reversible prepubertal gynecomastia.

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. All linked terms and their corresponding definitions will appear as a glossary in the printable version of the summary.

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.

General Information

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. The proponents of aromatherapy claim it is an all-natural, nontoxic adjunct to conventional medicines.

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, as 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.[1]

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.[2]

Aromatherapy is used or claimed to be useful for a vast array of symptoms and conditions. A book on aromatherapy for children suggests aromatherapy remedies for everything from acne to whooping cough.[3] 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.[4] 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 direct inhalation via diffuser or drops of oil placed near the patient (e.g., on a pillow); aromatherapy massage, which is the application to the body of essential oils diluted in a carrier oil; and other direct and indirect applications such as placing drops of oil in bathwater, lotions, or dressings. Different aromatherapy practitioners may have different recipes for treating specific illnesses, 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 is available at several schools throughout the United States and United Kingdom; but there is no professional standardization, and no license is required to practice in either country. Thus, there is not a great deal of consistency in the specific treatments 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 drives the choice of oils, different researchers often choose different oils when studying the same applications. 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. There currently are 19 schools that offer certificate programs approved by NAHA. 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. Some other countries may have similar organizations.

Although essential oils are given internally by aromatherapists in France and Germany, their 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, however, and 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.

References:

1. Wildwood C: The Encyclopedia of Aromatherapy. Rochester, Vt: Healing Arts Press, 1996.
2. Dodd 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.
3. Worwood VA: Aromatherapy for the Healthy Child: More Than 300 Natural, Non-Toxic, and Fragrant Essential Oil Blends. Novato, Calif: New World Library, 2000.
4. Buchbauer 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.

History

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.[1] They link it historically to the use of infused oils and unguents in the Bible and ancient Egypt,[1] remedies used throughout the Middle Ages and the Renaissance,[2] and the burning of aromatic plants in various primitive 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.[2] Gattefosse proposed the use of aromatherapy to treat diseases in virtually every organ system, citing mostly anecdotal and case-based evidence.[2]

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,[3] 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 topicalantibacterial uses,[4] aromatherapy has also been proposed for use in wound care [5] and to treat a variety of localizedsymptoms and illnesses such as alopecia,eczema, and pruritus.[6,7,8,9,10] Aromatherapy has also been studied via inhalation for airway reactivity.[11]

Studies on aromatherapy have examined a variety of other conditions: sedation and arousal;[12,13] startle reflex and reaction time;[14,15] psychological states such as mood, anxiety, and general sense of well-being;[16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31]neurologic impairment;[24]chronicrenal failure;[25]agitation in patients with dementia;[32,33,34,35,36] smoking withdrawal symptoms;[37,38] motion sickness;[39]postoperativenausea;[40,41] nausea and emesis in combination with fatigue, pain, and anxiety in patients in labor;[26,27,42] pain alone;[43,44,45,46] and pain in combination with other symptoms.[23,24,26,27]

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,[47,48] generalized stress, anxiety,[49] and depression.[50] 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,[51] homebound patients with terminal disease,[52] and hospitalized patients with leukemia.[53] Studies of aromatherapy use with mental health patients have also been conducted.[54,55] 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. Some authors propose that the extraction of essential oils from whole aromatic plants causes them to contain a life force or vitality that allegedly sets essential oils apart from other (synthetic) fragrances.[56] This argument suggests 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).[56] 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; however, it is primarily theoretical because of the lack of significant research addressing this topic.

References:

1. Tisserand 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.
2. Gattefosse RM: Gattefosse's Aromatherapy. Essex, England:CW Daniel, 1993.
3. Valnet J: The Practice of Aromatherapy: A Classic Compendium of Plant Medicines & Their Healing Properties. Rochester, NY: Healing Arts Press, 1990.
4. Dryden 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.
5. Hartman D, Coetzee JC: Two US practitioners' experience of using essential oils for wound care. J Wound Care 11 (8): 317-20, 2002.
6. Baker J: Essential oils: a complementary therapy in wound management. J Wound Care 7 (7): 355-7, 1998.
7. Asquith S: The use of aromatherapy in wound care. J Wound Care 8 (6): 318-20, 1999.
8. Hay IC, Jamieson M, Ormerod AD: Randomized trial of aromatherapy. Successful treatment for alopecia areata. Arch Dermatol 134 (11): 1349-52, 1998.
9. Anderson C, Lis-Balchin M, Kirk-Smith M: Evaluation of massage with essential oils on childhood atopic eczema. Phytother Res 14 (6): 452-6, 2000.
10. Ro 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.
11. Cohen BM, Dressler WE: Acute aromatics inhalation modifies the airways. Effects of the common cold. Respiration 43 (4): 285-93, 1982.
12. Diego 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.
13. Motomura N, Sakurai A, Yotsuya Y: Reduction of mental stress with lavender odorant. Percept Mot Skills 93 (3): 713-8, 2001.
14. Miltner 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.
15. Millot JL, Brand G, Morand N: Effects of ambient odors on reaction time in humans. Neurosci Lett 322 (2): 79-82, 2002.
16. Stevenson C: Measuring the effects of aromatherapy. Nurs Times 88 (41): 62-3, 1992 Oct 7-13.
17. Dunn 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.
18. Buckle J: Aromatherapy. Nurs Times 89 (20): 32-5, 1993 May 19-25.
19. Hadfield N: The role of aromatherapy massage in reducing anxiety in patients with malignant brain tumours. Int J Palliat Nurs 7 (6): 279-85, 2001.
20. Wilkinson S: Aromatherapy and massage in palliative care. Int J Palliat Nurs 1 (1): 21-30, 1995.
21. Wilkinson S, Aldridge J, Salmon I, et al.: An evaluation of aromatherapy massage in palliative care. Palliat Med 13 (5): 409-17, 1999.
22. Corner 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.
23. Louis 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.
24. Walsh E, Wilson C: Complementary therapies in long-stay neurology in-patient settings. Nurs Stand 13 (32): 32-5, 1999 Apr 28-May 4.
25. Itai T, Amayasu H, Kuribayashi M, et al.: Psychological effects of aromatherapy on chronic hemodialysis patients. Psychiatry Clin Neurosci 54 (4): 393-7, 2000.
26. Burns E, Blamey C: Complementary medicine. Using aromatherapy in childbirth. Nurs Times 90 (9): 54-60, 1994 Mar 2-8.
27. Burns 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.
28. Kite SM, Maher EJ, Anderson K, et al.: Development of an aromatherapy service at a Cancer Centre. Palliat Med 12 (3): 171-80, 1998.
29. Komori 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.
30. Wiebe E: A randomized trial of aromatherapy to reduce anxiety before abortion. Eff Clin Pract 3 (4): 166-9, 2000 Jul-Aug.
31. Lehrner J, Eckersberger C, Walla P, et al.: Ambient odor of orange in a dental office reduces anxiety and improves mood in female patients. Physiol Behav 71 (1-2): 83-6, 2000 Oct 1-15.
32. Ballard 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.
33. Smallwood 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.
34. Holmes 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.
35. Gray 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.
36. Cohen-Mansfield J, Werner P: The effects of an enhanced environment on nursing home residents who pace. Gerontologist 38 (2): 199-208, 1998.
37. Rose JE, Behm FM: Inhalation of vapor from black pepper extract reduces smoking withdrawal symptoms. Drug Alcohol Depend 34 (3): 225-9, 1994.
38. Sayette MA, Parrott DJ: Effects of olfactory stimuli on urge reduction in smokers. Exp Clin Psychopharmacol 7 (2): 151-9, 1999.
39. Post-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.
40. Tate S: Peppermint oil: a treatment for postoperative nausea. J Adv Nurs 26 (3): 543-9, 1997.
41. Hines S, Steels E, Chang A, et al.: Aromatherapy for treatment of postoperative nausea and vomiting: a Cochrane systematic review. [Abstract] 211, 2009.
42. Oyama 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.
43. Dale 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.
44. Göbel 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.
45. Marchand S, Arsenault P: Odors modulate pain perception: a gender-specific effect. Physiol Behav 76 (2): 251-6, 2002.
46. Kim JT, Wajda M, Cuff G, et al.: Evaluation of aromatherapy in treating postoperative pain: pilot study. Pain Pract 6 (4): 273-7, 2006.
47. Barclay 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.
48. Kohara 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.
49. Buckle J: Clinical Aromatherapy: Essential Oils in Practice. 2nd ed. New York, NY: Churchill Livingston, 2003.
50. Wilkinson 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.
51. Styles JL: The use of aromatherapy in hospitalized children with HIV disease. Complement Ther Nurs Midwifery 3 (1): 16-20, 1997.
52. Rimmer L: The clinical use of aromatherapy in the reduction of stress. Home Healthc Nurse 16 (2): 123-6, 1998.
53. Stringer J: Massage and aromatherapy on a leukaemia unit. Complement Ther Nurs Midwifery 6 (2): 72-6, 2000.
54. Hicks G: Aromatherapy as an adjunct to care in a mental health day hospital. J Psychiatr Ment Health Nurs 5 (4): 317, 1998.
55. Mantle F: The role of alternative medicine in treating postnatal depression. Complement Ther Nurs Midwifery 8 (4): 197-203, 2002.
56. Dodd 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.

Laboratory / Animal / Preclinical Studies

Numerous studies on the topicalantibacterial effects of essential oils have been published; most have found the oils to have significantantimicrobial activity.[1]

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 [2] 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.[3,4] Two studies from Japan showed an improvement in immunological and behavioral markers in rats exposed to fragrances while under stressful conditions.[5,6]

References:

1. Aridogan BC, Baydar H, Kaya S, et al.: Antimicrobial activity and chemical composition of some essential oils. Arch Pharm Res 25 (6): 860-4, 2002.
2. Buchbauer 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.
3. Aloisi 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.
4. Jahangeer AC, Mellier D, Caston J: Influence of olfactory stimulation on nociceptive behavior in mice. Physiol Behav 62 (2): 359-66, 1997.
5. Shibata H, Fujiwara R, Iwamoto M, et al.: Immunological and behavioral effects of fragrance in mice. Int J Neurosci 57 (1-2): 151-9, 1991.
6. Fujiwara 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.

Human / Clinical Studies

No studies in the published peer-reviewed literature discuss aromatherapy as a treatment for 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.

Among the fewest articles published on the subject are clinical trials involving aromatherapy. A major review published in 2000 [1] 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.[2] Forty-six patients were randomly assigned to conventional day care alone or day care plus weekly aromatherapy massage using a standardized blend of oils 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.[3] 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.[4] 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).[5] 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.

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.[6] 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 malignantbrain tumors attending their first follow-up appointment after radiation therapy.[7] 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 woundinfections. Compounded phytochemicals, such as lemongrass, eucalyptus, melaleuca, clove, thyme with butylated hydroxyl toluene, triclosan (0.3%), and 95 undenatured ethanol (69.7%) are being investigated against MRSA in vitro. No clinical trials have been performed.[8]

Two topical MRSA eradication regimens were compared in hospital patients. A standard treatment, which included mupirocin 2% nasalointment, chlorhexidine gluconate 4% soap, and silver sulfadiazine 1% cream was given versus a tea tree oil regimen, 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.[9]

References:

1. Cooke B, Ernst E: Aromatherapy: a systematic review. Br J Gen Pract 50 (455): 493-6, 2000.
2. Wilcock 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.
3. Soden 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.
4. Graham 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.
5. Wilkinson S, Aldridge J, Salmon I, et al.: An evaluation of aromatherapy massage in palliative care. Palliat Med 13 (5): 409-17, 1999.
6. Kite SM, Maher EJ, Anderson K, et al.: Development of an aromatherapy service at a Cancer Centre. Palliat Med 12 (3): 171-80, 1998.
7. Hadfield N: The role of aromatherapy massage in reducing anxiety in patients with malignant brain tumours. Int J Palliat Nurs 7 (6): 279-85, 2001.
8. Sherry E, Boeck H, Warnke PH: Percutaneous treatment of chronic MRSA osteomyelitis with a novel plant-derived antiseptic. BMC Surg 1: 1, 2001.
9. Dryden 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.

Adverse Effects

Safety testing on essential oils has shown minimal adverse effects. Several oils have been approved for use as food additives and are classified as generally recognized as safe (GRAS) 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.[1] 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 inhaledaromatherapy without massage.[2] Most 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 has been associated with reversible prepubertal gynecomastia.[3] Lavender and tea tree oils have estrogenic and antiandrogenic activities, and there is a theoretical concern for women at high risk for hormonally sensitive breast cancer when using lavender and tea tree oils.[3]

References:

1. Bilsland 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.
2. Schaller M, Korting HC: Allergic airborne contact dermatitis from essential oils used in aromatherapy. Clin Exp Dermatol 20 (2): 143-5, 1995.
3. Henley 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.

Overall Level of Evidence for Aromatherapy and Essential Oils

To assist readers in evaluating the results of human studies of complementary and alternative medicine (CAM) treatments for 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 therapeuticoutcome or outcomes, such as tumorresponse, 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 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

No. = number; QOL = quality of life.
a Patients with cancer.
b Patients with breast cancer undergoing bone marrow transplantation.
c Patients with malignantbrain tumors.
d Lavender (43%), rosewood (29%), rose (7%), and valerian (4%).
Reference Citations Type of Study/Essential Oil/Mode of Administration No. of Patients Enrolled; Treated; Control Condition Investigated Primary Outcome Secondary Outcome Level of Evidence Score
[1] Randomizednonblinded triala /lavender (Lavandula angustifolia Miller [synonyms: Lavandula spicata L.; Lavandula vera DC.]) and chamomile blend/massage 46; 11; 18 Mood, QOL, physical symptoms No effect on mood, QOL, or physical symptoms None 1ii
[2] Randomized nonblinded triala /lavender/massage 42; 29; 13 Pain No effect on pain Improved sleep in both groups; reduced depression (in massage group); no effect on QOL 1ii
[3] Double-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 application 313 Anxiety No effect on anxiety No effect on depression or fatigue 1i
[4] Nonrandomized controlled clinical trialb /lavender, eucalyptus (Eucalyptus globulus Labill. and Eucalyptus radiata Sieber ex DC. [Myrtaceae]), tea tree/topical application 16; 6; 10 Infection No effect on incidence of infection None 2
[5] Nonrandomized 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 turmericphytol/oral application 48; 24; 24 Gastrointestinal symptoms No effect on gastrointestinal symptoms None 2
[6] Consecutive case seriesc /lavender or chamomile/massage 18; 8 Anxiety, depression No reduction in anxiety or depression Reduction in blood pressure, pulse, and respiration 3ii
[7] Randomized nonblinded triala /chamomile/massage 103; 43; 44 Physical and psychological symptoms, QOL Reduction in anxiety and in physical and psychological symptoms; improved QOL None 1ii
[8] Randomized nonblinded triala /chamomile/massage 52; 26; 25 QOL, physical symptoms, anxiety Improved QOL, fewer physical symptoms, reduced anxiety None 1ii
[9] Randomized nonblinded triala /aromatherapy blendd /massage 52; 34; 18 Anxiety, mobility Decreased anxiety, pain; improved mobility None 1ii
[10] Consecutive casea /various oils/massage 69 General symptoms General improvement in symptoms reported by patients; no statistical analysis completed None 3ii

References:

1. Wilcock 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.
2. Soden 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.
3. Graham 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.
4. Gravett P: Aromatherapy treatment for patients with Hickman line infection following high-dose chemotherapy. International Journal of Aromatherapy 11 (1): 18-9, 2001.
5. Gravett P: Treatment of gastrointestinal upset following high-dose chemotherapy. International Journal of Aromatherapy 11 (2): 84-6, 2001.
6. Hadfield N: The role of aromatherapy massage in reducing anxiety in patients with malignant brain tumours. Int J Palliat Nurs 7 (6): 279-85, 2001.
7. Wilkinson S, Aldridge J, Salmon I, et al.: An evaluation of aromatherapy massage in palliative care. Palliat Med 13 (5): 409-17, 1999.
8. Wilkinson S: Aromatherapy and massage in palliative care. Int J Palliat Nurs 1 (1): 21-30, 1995.
9. Corner 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.
10. Evans 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 (01 / 08 / 2010)

The PDQcancer information summaries are reviewed regularly and updated as new information becomes available. This section describes the latest changes made to this summary as of the date above.

GENERAL INFORMATION

Added text to state that the National Association for Holistic Aromatherapy and the Alliance of International Aromatherapists are the two governing bodies for national educational standards for aromatherapists.

Added text to state that the Canadian Federation of Aromatherapists has established standards for aromatherapy certification in Canada.

Added text about the International Federation of Aromatherapists, which includes a list of international aromatherapy programs.

HISTORY

Added text about motion sickness to the studies on aromatherapy conditions (cited Post-White et al. as reference 39, Hines et al. as reference 41, and Kim et al. as reference 46).

Added text about lymphedema and depression to the published articles that have described the use of aromatherapy in specific hospital settings (cited Barclay et al. as reference 47, Kohara et al. as reference 48, and Wilkinson et al. as reference 50).

OVERALL LEVEL OF EVIDENCE FOR AROMATHERAPY AND ESSENTIAL OILS

Revised text in the second row of the table to clarify that there was improved sleep in both groups, reduced depression in the massage group, and no effect on quality of life.

More Information

ADDITIONAL INFORMATION ABOUT CAM THERAPIES

  • The National Center for Complementary and Alternative Medicine (NCCAM).
  • The National Cancer Institute Office of Cancer Complementary and Alternative Medicine (OCCAM).
  • CAM on PubMed, a special subset of the PubMed scientific literature database created through a partnership between NCCAM and the National Library of Medicine.

ABOUT PDQ

  • PDQ® - NCI's Comprehensive Cancer Database
    Full description of the NCI PDQ database.

OTHER PDQ SUMMARIES

  • PDQ® Cancer Information Summaries: Adult Treatment
    Treatment options for adult cancers.
  • PDQ® Cancer Information Summaries: Pediatric Treatment
    Treatment options for childhood cancers.
  • PDQ® Cancer Information Summaries: Supportive and Palliative Care
    Side effects of cancer treatment, management of cancer-related complications and pain, and psychosocial concerns.
  • PDQ® Cancer Information Summaries: Screening/Detection (Testing for Cancer)
    Tests or procedures that detect specific types of cancer.
  • PDQ® Cancer Information Summaries: Prevention
    Risk factors and methods to increase chances of preventing specific types of cancer.
  • PDQ® Cancer Information Summaries: Genetics
    Genetics of specific cancers and inherited cancer syndromes, and ethical, legal, and social concerns.
  • PDQ® Cancer Information Summaries: Complementary and Alternative Medicine
    Information about complementary and alternative forms of treatment for patients with cancer.

IMPORTANT:

This information is intended mainly for use by doctors and other health care professionals. If you have questions about this topic, you can ask your doctor, or call the Cancer Information Service at 1-800-4-CANCER (1-800-422-6237).

Date Last Modified: 2010-01-08

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