Research and clinical trials about essential oils Page (From the University of Minnesota)
- Who is doing the research?
- What does the research say?
- References and current studies
- How Do Essential Oils Work?
- Aromatherapy and Essential Oils on limited Human/Clinical Studies
Although essential oils have been used therapeutically for centuries, there is little published research on many of them. However, this is beginning to change as more scientific studies on essential oils are conducted around the world.
Clinical studies are currently underway in Europe, Australia, Japan, India, the United States, and Canada. Many of these studies describe the remarkable healing properties of various oils.
1. Who is doing the research?
A significant body of research on essential oils has been conducted by the food, flavoring, cosmetics, and tobacco industries. They are most interested in the flavor, mood alteration, and preservative qualities of essential oils. S ome of these companies have also conducted extensive research on the toxicity and safety of essential oils. Although much of this research is proprietary and not generally available to consumers, some of it has made its way into cosmetic and plant product journals. These journals are important sources of information as we accumulate a growing body of knowledge on essential oils. Most of the studies that have been published in the English language scientific literature have been conducted in laboratories and they have not been tested on humans, but this is changing.
What are some issues in conducting research on essential oils?
There are some unique issues in conducting research on essential oils.
Essential Oils Are Not Standardized:
The chemistry of essential oils is influenced by the local geography and weather conditions, as well as the season and time of day when the plants are harvested, how they are processed, and how they are packaged and stored. Each plant is unique in its chemistry so essential oils are never exactly the same-this is different from pharmaceutical drugs that are synthetically reproduced to be identical every time. Essential oils can be altered to achieve standardization (for example, a certain chemical that was found to be at a lower concentration in the whole oil in a particular year can be added to make it the same percentage as last year’s batch). The problem with standardized essential oils is that they are no longer natural, genuine, and authentic. This variability in essential oils by time, place and conditions is a big challenge to conducting valid research. Currently the International Standards Organization sets standards for each essential oil that include a range of acceptable concentrations for its major chemical constituents.
It Is Difficult to Conduct Blinded Studies with Aromatic Substances:
Typical research studies involve testing two groups-one group gets an experimental substance and another group gets a placebo substance (this group is referred to as the “control” group). When using aromatic substances, it is very difficult to conduct a blinded study. Some researchers have used masks or other barriers to blind participants. Other researchers have used alternate scents assumed to have no therapeutic properties as controls. These approaches are problematic, however, because people associate smells with past experiences. Thus, it is difficult to account for individual variation in how essential oils affect people.
It Is Difficult to Get Approval and Funding for Research on Essential Oils:
Essential oils have been used on humans for thousands of years. As a result, they don’t fit into the conventional clinical science approach of testing a substance in the lab first, then on animals, and then on humans. As a result, if a researcher proposes to test an essential oil with humans first, they may be turned down. This is because research review boards tend to approve research studies that follow the more usual scientific research path. Many conventional drug studies are funded by the pharmaceutical industry. There is little motivation for these companies to fund research on natural plant substances because they cannot easily be patented, limiting the potential for profit. Thus, finding funding for essential oils studies can be challenging.
It Is Difficult to Tell What Caused the Outcome:
In conventional research studies, it is important to be able to determine exactly what caused the outcome. In essential oil therapy, the oils are sometimes applied with massage, which makes it difficult to tell whether or not the outcome was due to the essential oil alone, or the massage, or the combination. Also, essential oils are composed of hundreds of chemical constituents, and it is hard to determine which ones may have produced the desired effect.
2. What does the research say?
Research studies on essential oils show positive effects for a variety of health concerns including infections, pain, anxiety, depression, tumors, premenstrual syndrome, nausea, and many others. The resources on this page are meant to highlight a few examples.
3. References and current studies
Alexandrovich, I., Rakovitskaya, O., Kolmo, E., Sidorova, T., Shushunov, S. (2003). The effect of fennel (Foeniculum Volgare) seed oil emulsion in infantile colic: a randomized, placebo-controlled study. Alternative Therapies in Health and Medicine, 9(4), 58-61.
Al-Hader, A.A., Hasan, Z.A., Aqel, M.B. (1994). Hyperglycemic and insulin release inhibitory effects of rosmarinus officinalis. Journal of Ethnopharmacology, 43, 217,22.
Al-Shuneigat, J., Cox, S. D., & Markham, J. L. (2005). Effects of a topical essential oil-containing formulation on biofilm-forming coagulase-negative staphylococci. Letters in Applied Microbiology, 41(1), 52-55.
Anderson, L., Gross, J. (2004). Aromatherapy with peppermint, isopropyl alcohol, or placebo is equally effective in relieving postoperative nausea. Journal of Peri-Anesthesia Nursing, 19, (1), 29-35.
Bagg, J., Jackson, M. S., Petrina Sweeney, M., Ramage, G., & Davies, A. N. (2006). Susceptibility to melaleuca alternifolia (tea tree) oil of yeasts isolated from the mouths of patients with advanced cancer. Oral Oncology, 42(5), 487-492.
Ballard, C.G., O’Brien, J.T., Reichelt, K., Perry, E.K. (2002). 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. Journal of Clinical Psychiatry, 63, 553-8.
Barker, S & Altman P. (2010). A randomized, assessor blind, parallel group comparative efficacy trial of three products for the treatment of head lice in children – melaleuca oil and lavender oil, pyrethrins and piperonyl butoxide, and a “suffocation” product. BMC Dermatology, 10, 6.
Bassett, I. B., Pannowitz, D. L., & Barnetson, R. S. (1990). A comparative study of tea-tree oil versus benzoylperoxide in the treatment of acne. Med J Aust, 153(8), 455-458.
Benencia, F. (1999). Antiviral activity of sandalwood oil against Herpes simplex viruses-1 and -2. Phytomedicine 6(2), 119-23.
Bernardes W, Lucarini R, Tozatti M, Flauzino L, Souza M, Turatti I, Andrade e Silva M, martins C, da Silva Filho A & Cunha W. (2010). Antibacterial activity of the essential oil from Rosmarinus officinalis and its major components against oral pathogens.
Bouhdid, S, Abrini, J, Zhiri, A, Espuny, M & Manresa, A. (2009). Investigation of functional and morphological changes in Pseudomonas aeruginosa and Staphylococcus aureus cells induced by Origanum compactum essential oil. Journal of Applied Microbiology, 106 (5), 1558-1568.
Brady, A., Loughlin, R., Gilpin, D., Kearney, P., & Tunney, M. (2006). In vitro activity of tea-tree oil against clinical skin isolates of meticillin-resistant and -sensitive staphylococcus aureus and coagulase-negative staphylococci growing planktonically and as biofilms. Journal of Medical Microbiology, 55(Pt 10), 1375-1380.
Brandao, F. M. (1986). Occupational allergy to lavender oil. Contact Dermatitis, 249-50.
Buckle, J. (2007). Literature review: should nursing take aromatherapy more seriously? British Journal of Nursing, 16, (2), 116-120.
Burns, E., Blamey, C., Ersser, S. J., Barnetson, L., & Lloyd, A. (2000). An investigation into the use of aromatherapy in intrapartum midwifery Practice. The Journal of Alternative and Complementary Medicine, 6(2), 141-7.
Burns, E., Zobbi, V., Panzeri, D., Oskrochi, R., Regalia, A. (2007).
Aromatherapy in childbirth: a pilot randomized controlled trial. BJOG: An International Journal of Obstetrics & Gynaecology, 114(7), 838-44.
Burt, S. A. (2003). Antibacterial activity of selected plant essential oils against Escherichia coli O157:H7. Letters in Applied Microbiology 36, 162-7.
Caelli, M., Porteous, J., Carlson, C. F., Heller, R., & Riley, T. V. (2001).
Tea tree oil as an alternative topical decolonization agent for methicillin-resistant Staphylococcus Aureus. The International Journal of Aromatherapy 11(2). [Originally published in The Journal of Hospital Infection (2000), 46, 236-237.]
Canyon, D & Speare, R. (2007). A comparison of botanical and synthetic substances commonly used to prevent health lice (Pediculus humanus var. capitis) infestation. International Journal of Dermatology, 46(4), 422-426.
Cappello, G, Spezzaferro, M, Grossi, L, et al. (2007). Peppermint oil (Mintoil) in the treatment of irritable bowel syndrome: A prospective double blind placebo-controlled randomized trial. Digestive & Liver Disease, 39(6), 530-536.
Carson, C. F., Hammer, K. A., & Riley, T. V. (2006). Melaleuca alternifolia (tea tree) oil: A review of antimicrobial and other medicinal properties. Clinical Microbiology Reviews, 19(1), 50-62.
Chang, SY. (2008). Effects of aroma hand massage on pain, state anxiety and depression in hospice patients with terminal cancer. Daehan Ganho Haghoeji, 38(4), 493-502.
Chung, M, Cho, S, Bhuiyan, M, Kim, K & Lee, S. (2010). Anti-diabetic effects of lemon balm (Melissa officinalis) essential oil on glucose- and lipid-regulating enzymes in type 2 diabetic mice.British J of Nutrition, 104 (2), 180-188.
Cooke, B., Ernst, E. (2000). Review: aromatherapy massage is associated with small, transient reductions in anxiety. British Journal of General Practice, Jan, 50, 493-6.
Davies, SJ, Harding, LM & Baranowski, AP. (2002). A novel treatment of postherpetic neuralgia using peppermint oil. Clinical Journal of Pain, 18(3), 200-2.
De Groot, A.C., & Weyland, W. (1992). Systemic contact dermatitis from tea tree oil. Contact Dermatitis, 27, 279-80.
Dryden, M., Dailly, S., Crouch, M. (2004). A randomized, controlled trial of tea tree topical preparations versus a standard topical regimen for the clearance of MRSA colonization. Journal of Hospital Infec, 56, (4), 283-6.
Dwivedi, C. & Zhang, Y. (1999). Sandalwood oil prevents skin tumour development in CD1 mice. European Journal of Cancer Prevention, 8, 449-55.
Edris, A. (2007). Pharmaceutical and therapeutic potentials of essential oils and their individual volatile constituents: A review. Phytotherapy Research 21, 308-323.
Enshaieh, S., Jooya, A., Siadat, A. H., & Iraji, F. (2007). The efficacy of 5% topical tea tree oil gel in mild to moderate acne vulgaris: A randomized, double-blind placebo-controlled study. Indian Journal of Dermatology, Venereology & Leprology, 73(1), 22-25.
Furneri, P. M., Paolino, D., Saija, A., Marino, A., & Bisignano, G. (2006). In vitro antimycoplasmal activity of melaleuca alternifolia essential oil. Journal of Antimicrobial Chemotherapy, 58(3), 706-707.
Gao, Y. Y., Di Pascuale, M. A., Li, W., Baradaran-Rafii, A., Elizondo, A., Kuo, C. L., et al. (2005). In vitro and in vivo killing of ocular demodex by tea tree oil. British Journal of Ophthalmology, 89(11), 1468-1473.
Garozzo A, Timpanarao R, Stivala A, Bisignano G & Castro A. (2010) Activity of Melaleuca alternifolia (tea tree) oil on influenza virus A/PR/8: Study on the mechanism of action. Antiviral Research, 89 (1), 83-8.
Gedney, J., Glover, T., Fillingim, R. (2004). Sensory and affective pain discrimination after inhalation of essential oils. Psychosomatic Medicine, 66(4), 599-606.
Greenway, f, Frome & Engels, T. (2003). Temporary relief of postherpetic neuralgia pain with topical geranium oil. American J of Medicine, 115, 586-587.
Gustafson, J. E., Chew, S., Markham, J., Bell, H.C., Wyllie, S. G., & Warmington, J. R. (1988). Effects of tea tree oil on Escherichia coli. Letters in Applied Microbiology, 26, 194-8.
Hadfield, N. (2001). The role of aromatherapy massage in reducing anxiety in patients with malignant brain tumors. International Journal of Palliative Nursing, 7, (6), 279-285.
Hajhashemi, V., Ghannadi, A., & Sharif, B. (2003). Anti-inflammatory and analgesic properties of the leaf extracts and essential oil of lavandula angustifolia mill. Journal of Ethnopharmacology, 89(1), 67-71.
Halm, M. (2008). Essential oils for management of symptoms in critically ill patients. American Journal of Critical Care, 17, (2), 160-163.
Hammer, K. A., & Riley, T. V. (1998). In-vitro activity of essential oils, in particular Melaleuca alternifolia (tea tree) oil and tea tree oil products, against Candida spp. Journal of Antimicrobial Chemotherapy 42, 591-5.
Hammer, K. A., Carson, C. F., & Riley, T. V. (2004). Antifungal effects of melaleuca alternifolia (tea tree) oil and its components on candida albicans, candida glabrata and saccharomyces cerevisiae. Journal of Antimicrobial Chemotherapy, 53(6), 1081-1085.
Hammer, K. A., Carson, C. F., Riley, T. V., & Nielsen, J. B. (2006). A review of the toxicity of Melaleuca alternifolia (tea tree) oil. Food & Chemical Toxicology, 44(5), 616-625.
Han, S., Hur M., Buckle, J., Choi, J., Lee, M. (2006). Effect of aromatherapy on symptoms of dysmenorrheal in college students: A randomized placebo-controlled clinical trial. The Journal of Alternative and Complentary Medicine, Jul-Aug, 12(6), 535-41.
Hansen, T., Hansen, B., Ringdal, G. (2006). Does aromatherapy massage reduce job-related stress? Results from a randomized, controlled trial. International Journal of Aromatherapy, June, 16, (2), 89-94.
Hayashi, K., & Hayashi, T. (1994). Virucidal effects of the steam distilate from Houttuynia cordata and its components on HSV-1, influenza virus, and HIV. Planta Medica. 61, 237-41.
Haze, S, Sakai, K & Gozu, Y. (2002). Effects of fragrance inhalation on sympathetic activity in normal adults. Japanese Journal of Pharmacology, 90, 247-253.
Henley, D., Lipson, N., Korach, K., Bloch, C. (2007). Prepubertal gynecomastia linked to lavender and tea tree oils. The New England Journal of Medicine, Feb 1, 356, (5), 479-485. (SHOWN INVALID)
Inouye, S., Yamaguchi, H. (2001). Antibacterial activity of essential oils and their major constituents against respiratory tract pathogens by gaseous contact. Journal of Antimicrobial Chemotherapy, 47, 565-73.
Itai, T., Amayasu, H., Kuribayashi, M., Kawamura, N., Okada, M., Momose, A., Tateyama, T., Narumi, K., Waka, Kaneko, U.S. (2000). Psychological effects of aromatherapy on chronic hemodialysis patients. Psychiatry and Clinical Neurosciences, 54, 393-7.
Jandourek, A. & Vazquez, J. (1998). Efficacy of melaleuca oral solution for the treatment of fluconazole refractory oral candidiasis in AIDS patients. AIDS 12, 1033-7.
Kane, FM, Brodie, EE, Couli, A, et al. (2004). The analgesic effect of odour and music upon dressing change. British Journal of Nursing, 13(19), S4-12.
Kejova K, Jorova D, Bendova H, Gajdos P & Kolarova H. (2010). Phototoxicity of essential oils intended for cosmetic use. Toxicology in Vitro, 24 (8), 2084-9.
Khan, M, Zahin & Hassan, S. (2009). Inhibition of quorum sensing regulated bacterial functions by plant essential oils with special reference to clove oil. Letters in Applied Microbiology, 49, 354-360.
Kim, J. et al. (2006). Evaluation of aromatherapy in treating post-operative pain: pilot study. Pain Practice, 6(4), 273-277.
Lehrner, J., Marwinski, G., Lehr, S., Johren, P., & Deecke, L. (2005). Ambient odors of orange and lavender reduce anxiety and improve mood in a dental office. Physiology & Behavior, 86(1-2), 92-95.
Lemon, K. (2004). An assessment of treating depression and anxiety with aromatherapy. The International Journal of Aromatherapy, 14, 63-69.
Lucks, B.C., Sorensen, J., Veal, L. (2002). Vitex agnus-castus essential oil and menopausal balance: a self-care survey. Complementary Therapies in Nursing and Midwifery, 8, 148-54.
Messager, S., Hammer, K. A., Carson, C. F., & Riley, T. V. (2005). Assessment of the antibacterial activity of tea tree oil using the european EN 1276 and EN 12054 standard suspension tests. Journal of Hospital Infection, 59(2), 113-125.
Millar, B & Moore, J. (2008). Successful topical treatment of hand warts in a paediatric patient with tea tree oil (Melaleuca alternifolia). Complementary Therapies in Clinical Practice, 14(4), 225-27.
Nguyen, Q., Paton C. (2008). The use of aromatherapy to treat behavioral problems in dementia. International Journal of Geriatric Psychiatry, 23, 337-346.
Oyedele, A. O., Gbolade, A. A., Sosan, M.B., Adewoyin, F. B., Soyelu, O.L., & Orafidiya, O. O. (2002). Formulation of an effective mosquito-repellent topical product from Lemongrass oil. Phytomedicine, 9, 259-62.
Price, S. & Price, L. (2007). Aromatherapy for health professionals, 3rd Ed. Philadelphia: Churchill Livingstone Elsevier.
Rose, J. E. & Behm, F. M. (1994). Inhalation of vapor from black pepper extract reduced smoking withdrawal symptoms. Drug and Alcohol Dependence, 34, 225-9.
Saeki, Y. (2000). The effect of foot bath with or without the essential oil of lavender on the autonomic nervous system: a randomized trial. Complementary Therapies in Medicine, 8, 2-7.
Sharma S, Araujo M, Wu M, Qaqush J & Charles C. (2010). Superiority of an essential oil mouthrinse when compared with a 0.05% cetylpyridinium chloride containing mouthrinse: A sis-month study, International Dental Journal, 60 (3), 175-80.
Sherry, E., Warnke, P. H. (2001). Percutaneous treatment of chronic MRSA osteomyelitis with a novel plant-derived antiseptic. BMC Surgery 1(1).
Snow L, Hovanec L & Brandt J. (2004). A controlled trial of aromatherapy for agitation in nursing home patients with dementia. J Alternative & Complementary Medicine, 10 (3), 431-437.
Soukoulis, S., & Hirsch, R. (2004). The effects of a tea tree oil-containing gel on plaque and chronic gingivitis. Australian Dental Journal, 49(2), 78-83.
Srivasta, K. C., Mustafa, T. (1992). Ginger (Zingiber officinale) in Rheumatism and Musculoskeletal Disorders. Medical Hypotheses, 39, 342-8.
Takarada, R. et al. (2004). A comparison of the antibacterial efficacies of essential oils against oral pathogens. Oral Microbiology and Immunology, 19, 61-64.
Toloza A, Zygadlo J, Biurrun F, Rotman A & Picollo M. (2010). Bioactivity of Argentinean essential oils against permethrin-resistant head lice, Pediculus humanus capita. J of Insect Science, 10, 185.
Torres Salazar A, Hoheisel J, Youns M & Wink M. (2011). Anti-inflammatory and anti-cancer activities of essential oils and their biological constituents. International J of Clinical Pharmacology & Therapeutics, 49 (1), 93-95.
Tyagi A & Malik A. (2010). Liquid and vapour-phase antifungal activities of selected essential oils against Candida albicans: Microscopic observations and chemical characterization of Cymbopogon citratus. BMC Complementary & Alternative Medicine, 10, 65.
Van der Ploeg E, Eppingstall B & O’Connor D. (2010). The study protocol of a blinded randomized-controleed cross-over trial of lavender oil as a treatment of behavioural symptoms in dementia. BMC Geriatrics, 10, 49.
Woelk, H & Schlafke, S. (2009). A multi-center, double-blind, randomizsed study of the lavender oil preparation Silexan in comparison to Lorazepam for generalized anxiety disorder. Phytomedicine, 17, 94-99.
4. How Do Essential Oils Work?
Essential oils enter the body in three ways.
They can be:
- Applied to the skin
How does skin application work?
Essential oils can be applied topically to the skin. Common examples include applying a blend that contains black pepper (Piper nigrum) or ginger (Zinziber officinalis) essential oil to reduce arthritis pain and improve flexibility, or applying German Chamomile (Matricaria recutita) essential oil to treat eczema.
How does this work? Our skin is somewhat permeable. The active chemicals in essential oils are absorbed just like the ingredients in common pharmaceuticals such as hormone replacement therapy cream and nicotine patches.
Factors That Increase Skin Absorption
Different factors can affect the absorption of essential oils through the skin. If you massage the area first, it will increase circulation to that area, thereby causing an increase in absorption of essential oils. Heat will likewise increase circulation and thus enhance absorption. Some researchers report that essential oils may be more readily absorbed from skin locations with greater concentrations of sweat glands and hair follicles, such as the genitals, head, soles, palms, and armpits (Battaglia, 2003).
How do I inhale essential oils?
Another way that essential oils enter the body is inhalation through the nose or mouth. Common examples include inhaling eucalyptus (Eucalyptus globules, E. radiate, or E. smithii) essential oil when you have a cough or inhaling peppermint (Mentha piperita) essential oil to reduce fatigue or nausea.
(Note: Often, essential oils are put into a diffuser for inhalation. The section How Do I Choose and Use Essential Oils? describes this in more detail.)
The Olfactory System
The olfactory system includes all physical organs or cells relating to, or contributing to, the sense of smell. When we inhale through the nose, airborne molecules interact with the olfactory organs and, almost immediately, the brain. Molecules inhaled through the nose or mouth are also carried to the lungs and interact with the respiratory system. Thus, inhaled essential oils can affect the body through several systems and pathways.
Interaction with the Limbic System (Emotional Brain)
During inhalation, odor molecules travel through the nose and affect the brain through a variety of receptor sites, one of which is the limbic system, which is commonly referred to as the “emotional brain.”
The limbic system is directly connected to those parts of the brain that control heart rate, blood pressure, breathing, memory, stress levels, and hormone balance (Higley & Higley, 1998). This relationship helps explain why smells often trigger emotions. Knowing this, we can hypothesize how inhalation of essential oils can have some very profound physiological and psychological effects!
“Smell is a potent wizard that transports us across thousands of miles and all the years we have lived.”
– Helen Keller
Do people ingest essential oils?
The third way that essential oils enter the body is by ingestion (swallowing). Oral ingestion of essential oils is NOT recommended for the general public because a great deal of essential oils knowledge and expertise is necessary for safe practice.
The ingestion of essential oils is not common practice in the US. In France, it is more common, but only when specially trained physicians and pharmacists prescribe and dispense them. There are several reasons for caution, including the following:
- Some essential oils can be toxic to the liver or kidneys when ingested.
- Chemical breakdown of essential oils during gastric processing can change the effects.
- There could be potential drug interactions. (Tisserand and Balacs, 1995; Schnaubelt, 1999)
Battaglia, S., (2003). The complete guide to aromatherapy. Brisbane, Queensland, Australia: The International Centre of Aromatherapy.
Higley, C., Leatham, P. & Higley, A. (1998). Aromatherapy A-Z. Hay House.
Price, S. & Price, L. (2007). Aromatherapy for health professionals, 3rd Ed. Philadelphia: Churchill Livingstone Elsevier.
Schnaubelt, K. (1999). Medical aromatherapy: Healing with essential oils. Berkeley, CA: Frog, Ltd.
Tisserand, R. & Balacs, T. (1995). Essential oil safety: A guide for health professionals. Edinburgh: Churchill Livingstone.
Linda Halcón, PhD, MPH, RN
5. Aromatherapy and Essential Oils on limited Human/Clinical Studies
Current Clinical Trials
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.
Among the fewest articles published on the subject are clinical trials involving aromatherapy. 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 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 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 around 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. 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.
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, 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.
- Cooke B, Ernst E: Aromatherapy: a systematic review. Br J Gen Pract 50 (455): 493-6, 2000. [PUBMED Abstract]
- 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. [PUBMED Abstract]
- 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. [PUBMED Abstract]
- 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. [PUBMED Abstract]
- Wilkinson S, Aldridge J, Salmon I, et al.: An evaluation of aromatherapy massage in palliative care. Palliat Med 13 (5): 409-17, 1999. [PUBMED Abstract]
- Ndao 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 : , 2010. [PUBMED Abstract]
- Potter 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. [PUBMED Abstract]
- Kite SM, Maher EJ, Anderson K, et al.: Development of an aromatherapy service at a Cancer Centre. Palliat Med 12 (3): 171-80, 1998. [PUBMED Abstract]
- 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. [PUBMED Abstract]
- Sherry E, Boeck H, Warnke PH: Percutaneous treatment of chronic MRSA osteomyelitis with a novel plant-derived antiseptic. BMC Surg 1: 1, 2001. [PUBMED Abstract]
- 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. [PUBMED Abstract]