The report is a product of the VA/HSR&D Evidence Synthesis Program.
Aromatherapy and Essential Oils: A Map of the Evidence
VA is increasing the use of effective new practices and approaches in healthcare as part of its transformation to a more patient-centered healthcare model that focuses on the Veterans’ goals and priorities for their health. The use of various low-risk complementary health interventions also has been increasing both within and outside of the VA healthcare system. Essential oils (EOs) are part of a tradition of herbal medicine dating back thousands of years. EOs are volatile oils that contain the “essence” of an aromatic plant’s fragrance. The therapeutic inhalation of EOs is considered to have physiological and/or psychological benefits. Aromatherapy using EO is thought to mediate emotional responses by affecting the neuroendocrine system and autonomic nervous systems. In addition, there are various topical EO applications that are purported to be beneficial apart from their aromatic qualities (e.g., as antiseptics). The chemical components of EOs also have been shown to inhibit microbial and fungal growth. EO aromatherapy is being used increasingly in hospitals and other healthcare settings. For instance, aromatherapy has been used to help manage the behavioral and psychological symptoms of dementia, such as restlessness and aggression, and to improve sleep. However, despite their increasing use, little is known about the benefits and risks associated with the use of EOs.
VA’s Evidence Synthesis Program (ESP) Center in Portland, OR conducted a review to provide VA with a broad overview of the effectiveness of aromatherapy and essential oils (EOs), and the health conditions for which these interventions have been examined. Investigators searched multiple databases from inception through February 2019 for systematic reviews (SRs) of aromatherapy and EOs for health conditions, identifying 25 SRs that were selected for the evidence map (see below): 22 SRs provide evidence on inhaled EO interventions, which encompass aromatherapy combined with massage (EO-massage) as well as inhaled-only aromatherapy, while 3 SRs provide evidence on topical EO interventions. Evidence from 171 eligible trials is represented among the 25 SRs.
Categories of overall effectiveness—
- No effect: a preponderance of null or negative findings.
- Unclear: the systematic review reported mixed findings for a single outcome, or mixed findings across multiple outcomes within the same category, with no preponderance of either benefit or negative effects.
- Potential positive effect: multiple outcomes within the same category (pain/physical, nauseas/vomiting, psychological, global health, or sleep) with at least 1 clear finding of benefit; or mixed findings for a single outcome with a preponderance of evidence of a positive effect.
- Positive effect: numerous studies or a large sample showing a positive effect.
Levels of confidence in the evidence—
- High: Consistent findings from at least two studies with a large combined sample size and low risk of bias.
- Moderate: Evidence comes from a single large study with no major flaws, or from two+ studies with limitations in sample size, study quality, applicability, or consistency of findings.
- Low: Small combined sample size, or major deficiencies in the body of evidence.
- Insufficient: The body of evidence consists of only one small study or has unacceptable deficiencies.
This report and evidence map characterize the current knowledge about the effectiveness of inhaled and topical essential oils – and will inform decision-making about these modalities within the VA healthcare system.
Summary of Conclusions
There is moderate confidence that aromatherapy is effective for pain in dysmenorrhea (menstrual cramps). Investigators found potential positive effects of aromatherapy for:
- Pain in labor/childbirth;
- Blood pressure reduction in those with hypertension;
- Stress, depression, and sleep in patients on hemodialysis;
- Stress in healthy adults;
- Anxiety in perioperative patients undergoing various types of surgery; and
- Sleep quality in various populations, with low to moderate confidence in the evidence.
For EOs applied topically, there is moderate confidence in the potentially positive effect of tea tree oil for tinea
pedis. There is insufficient evidence with which to determine whether aromatherapy or topically
applied EO is effective for all other examined conditions.
Research Gaps/Future Research
The evidence map highlights many potential areas for future research. The interventions and health
conditions for which there was evidence of a "potential positive effect" may be one place to start
to prioritize research. The comparative effectiveness of different, standardized aromatherapeutic approaches should be examined, especially in conditions for which there is potential promise. Future studies should
capture potential adverse effects data, and the safety of aromatherapy should be examined in
patients with comorbidities, particularly those of the respiratory tract. Also, the use of a
non-EO fragrance comparator would improve blinding and allow comparison of effects and
harms of aromatherapy containing EO versus synthetically generated fragrance oils.
A Cyberseminar titled “Aromatherapy and Essential Oils: An Evidence Map” will be held on March 11, 2020 from 1:00pm – 2:00pm ET. Register here.
Freeman M, Ayers CK, Peterson C, and Kansagara D. Aromatherapy and Essential Oils: A Map of the Evidence. Washington, DC: Evidence Synthesis Program, Health Services Research and Development Service, Office of Research and Development, Department of Veterans Affairs. VA ESP Project #05-225; 2019.
To view the full report, go to http://www.hsrd.research.va.gov/publications/esp/aromatherapy.cfm
ESP is currently soliciting review topics from the broader VA community. Nominations will be accepted electronically using the online Topic Submission Form. If your topic is selected for a synthesis, you will be contacted by an ESP Center to refine the questions and determine a timeline for the report.
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