Exploring Aromatherapy as a Complementary Approach in Palliative Care: A Systematic Review

Abstract

Background:

Palliative care, a cornerstone of comprehensive healthcare, prioritizes quality of life for individuals with life-threatening illnesses. Aromatherapy, with its holistic approach and patient-reported benefits, emerges as a promising complementary therapy for managing symptoms and enhancing well-being in palliative care.

Objective:

The objective of this systematic review is to assess the efficacy of aromatherapy interventions in symptom management, with a focus on pain, anxiety, nausea, and sleep disturbances among palliative care patients.

Design:

A comprehensive search was conducted across various databases to identify relevant studies. Eligibility criteria were applied, resulting in the inclusion of eight studies for analysis. The review assessed the efficacy of aromatherapy interventions, primarily through massage, in symptom management. Variations in intervention procedures and outcome measures were noted, necessitating a critical examination of the findings.

Results:

The review’s findings suggest promising outcomes associated with aromatherapy in palliative care. Aromatherapy interventions demonstrated significant efficacy in reducing pain, anxiety, nausea, and improving sleep quality among patients. However, considerable heterogeneity was observed across studies, highlighting the need for standardized methodologies and larger-scale trials.

Conclusion:

This systematic review underscores the potential of aromatherapy as a complementary intervention in palliative care. While the findings support its efficacy in symptom management, methodological inconsistencies across studies warrant further research. Standardized approaches and larger trials are essential to validate the tailored effectiveness of aromatherapy for different symptoms encountered in palliative care, ultimately enhancing its clinical utility and integration into therapeutic practices.

Introduction

Palliative care, an essential component of comprehensive health care, addresses the multifaceted needs of individuals grappling with life-threatening illnesses. Rooted in a patient-centered approach, palliative care prioritizes quality of life, focusing on symptom management, psychosocial support, and holistic well-being throughout the disease trajectory. As a complementary therapy within this domain, aromatherapy has garnered attention for its potential to alleviate distressing symptoms and improve the overall quality of life for patients undergoing palliative care.¹

Aromatherapy, the therapeutic use of aromatic plant extracts and essential oils, embodies a holistic modality that engages olfactory and tactile senses, influencing emotional, physical, and psychological realms.² Its application in palliative care extends beyond conventional medical interventions, offering a promising avenue for managing symptoms such as pain, anxiety, nausea, and sleep disturbances, among others.³ The multifaceted nature of aromatherapy and its perceived safety and patient-reported benefits has positioned it as a complementary strategy to conventional palliative care.^4,5

This systematic review aimed to critically examine the literature on aromatherapy in palliative care, examining efficacy, safety issues, and modality of use in symptoms in various applications. Combining evidence from different studies, this review seeks to clarify the potential of aromatherapy to alleviate symptoms and address patients’ emotional needs.

Methods

The review protocol is registered on PROSPERO (CRD42023482105). The systematic review approach followed Cochrane guidelines on evaluating evidence from randomized controlled trials (RCTs) on effectiveness. It provides a structured and transparent approach for rating confidence in effect estimates.

Research framework

The study proposes a qualitative methodology through a systematic literature review, enabling us to identify, evaluate, and interpret studies on aromatherapy in palliative care. This thematic area involves exploring the experiences, perceptions, and qualitative data on using aromatherapy as a complementary intervention for symptom management and overall well-being in palliative care settings.

Research question

The determination of the research question was used to define the scope to develop a clear focus for the study. This research question was developed in response to the needs of the chosen topic, namely:

RQ1: What is aromatherapy’s overall safety and efficacy as a complementary intervention in addressing symptoms and improving the quality of life in palliative care patients?

RQ2: What specific symptoms (e.g., pain, anxiety, nausea, sleep disturbances) are most commonly targeted by aromatherapy in palliative care, and what evidence supports its effectiveness for each symptom?

Literature search

To address the research objectives of this study, a comprehensive literature search was conducted to identify relevant articles related to the scientific evidence that supports the efficacy and safety of aromatherapy in palliative medicine. The search was performed in the following databases: b-on, PubMed, Web of Science, and Scopus. These databases were selected based on their coverage of relevant fields, including the medical, nursing, and complementary and alternative medicine literature. The search strategy involved a combination of Medical Subject Headings (MeSH) terms, keywords, and Boolean operators, including but not limited to “aromatherapy,” “essential oils,” “palliative care,” “symptom management,” “end-of-life care,” “cancer patients,” and “quality of life.” These search terms were chosen to encompass the core elements of our research, ensuring that we capture articles addressing aromatherapy as a complementary intervention in palliative settings.

In addition, synonyms and related terms were included to maximize the retrieval of pertinent studies. This approach is intended to yield a comprehensive selection of peer-reviewed articles that meet our inclusion criteria and contribute to a thorough evaluation of the evidence on aromatherapy’s efficacy and safety in palliative medicine. The search included peer-reviewed articles published between January 2004 and February 2024 written in English, German, or Portuguese, the languages the researchers speak.

Inclusion criteria

The following studies were included: (1) RCTs and observational studies published in peer-reviewed journals. (2) Studies involving human participants aged 18 years or over, of any gender and ethnicity in a palliative care setting or described by the authors as having an advanced disease such as metastatic cancer or renal failure. (3) Studies that evaluate aromatherapy interventions, including the inhalation, topical application, or diffusion of essential oils. (4) Studies on various essential oils or aromatherapy techniques. (5) Studies reporting quantitative or qualitative data on the efficacy and safety of aromatherapy interventions in palliative care. (6) Studies that report outcomes related to symptom management (e.g., pain, anxiety, nausea, sleep disturbances), quality of life, patient and caregiver satisfaction, and adverse events.

Exclusion criteria

The following studies were excluded: (1) Gray literature, conference abstracts, unpublished studies, review articles, books, book chapters, and nonempirical studies. (2) Studies conducted on animals or in vitro studies that do not involve human participants. (3) Studies that do not involve patients in palliative care. (4) Studies assessing interventions other than aromatherapy (e.g., traditional pharmaceuticals, acupuncture). (5) Studies that do not specifically address aromatherapy as a primary intervention. (6) Studies lacking relevant data on the efficacy and safety of aromatherapy in palliative care. (7) Articles that do not report on symptom management or quality of life outcomes. (8) Studies published in languages other than English, German, or Portuguese. The search summary is summarized in Table 1.

Table 1.

The Search Strategy Summary

Items	Specification
Date of search	17/11/2023
Database and other sources searched	b-on, PubMed, Web of Science, and Scopus
Search terms used	Aromatherapy, Essential Oils, Palliative Care, End-of-Life Care, Symptom Management, Quality of Life
Timeframe	Articles published between January 2004 and February 2024
Inclusion criteria	All included studies were available in English and Portuguese; all selected studies were relevant to the review topic.
Exclusion criteria	Studies in other languages, only contained abstracts, papers published in conferences, books, or book chapters, and animal studies.
Selection process	The first and last authors selected all sources. The screening was undertaken in duplicate independently.

Types of outcomes measured

The primary outcomes of interest were the efficacy of essential oils and aromatherapy on symptom control in patients in palliative care and the occurrence of adverse events.

Study selection

The screening process was conducted in duplicate by independent reviewers. One author (S.G.) meticulously screened all citations (including records of title and, if available, abstract) to identify relevant studies initially. Simultaneously, another author (R.S.M.) performed a duplicate screening. In cases where a citation appeared relevant or lacked sufficient information for a decision, we retrieved the full-text article for further assessment. Any discrepancies in eligibility during screening and full-text assessment stages were anticipated to be resolved through discussion within the wider review team, ensuring a comprehensive and rigorous evaluation of the selected studies.

Risk of bias

One author (S.G.) assessed the risk of bias for each study using the criteria recommended by the Cochrane Collaboration;⁶ this was checked by the second author (R.S.M.), resolving any disagreements by discussion. We assessed risk for selection, performance, detection, attrition, and sample size.

Results

The search was executed in the selected databases, initially retrieving a total of 156 articles across all databases. All extracted references were added to a PubMed collection and exported to Rayyan⁷ for title and abstract screening. Duplicate articles were removed, and records marked as ineligible by the automation tool were removed, resulting in a preliminary pool of 94 unique articles. The search included peer-reviewed articles published between January 2004 and February 2024 written in English, German, or Portuguese, the researchers’ languages.

Titles and abstracts of the articles were reviewed to identify potentially relevant studies. Articles irrelevant to the research topic were excluded at this stage, leading to a refined set of 40 articles. Full-text access to these articles was obtained through institutional subscriptions and interlibrary loan services when necessary. However, six reports based on titles and abstracts were not retrieved during the screening process owing to inaccessibility to the full text. The search process and the inclusion of articles were documented and tracked using reference management software. The entire search process is summarized in a flowchart (Fig. 1), illustrating the number of articles identified, screened, and included at each stage by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.⁸

FIG. 1.

Diagram of article selection and inclusion process on the PRISMA methodology by Page et al.⁸

We obtained eight articles for analysis after the inclusion and exclusion criteria (Table 2).

Table 2.

Systematic Review Articles n = 8

Article number	Source title	Title	Abstract	Year	Reference
1	Asian Pacific Journal of Cancer Prevention	Effectiveness of Aromatherapy in Early Palliative Care for Oncology Patients: Blind Controlled Study	Background: Palliative care is the active holistic treatment of people of all ages who have serious health-related suffering as a result of severe illness, and especially of those who are close to the end of life. Palliative care is provided to cancer patients who experience serious suffering that cannot be relieved without professional intervention and that compromises physical, social, spiritual, and emotional functioning. A straightforward, low-risk, and affordable palliative care approach may be provided through aromatherapy, a type of complementary and alternative medicine. The study objective is to assess the comparative effectiveness of massage, aromatherapy massage, and massage combined with aromatherapy inhalation on cancer patients receiving palliative care.	2023	⁹
			Methods: A total of 100 participants who were divided into four groups at random. The first group, designated as the control group, received standard hospital nursing care, the second group received massage only (using the odorless almond carrier oil), the third group received massage with lavender oil, and the fourth group received combined (inhalation and massage) aromatherapy. The Rotterdam Symptom Checklist (RSCL), given two weeks after aromatherapy, was used to examine participants’ perspectives of care.
			Results: On the RSCL, combined aromatherapy performed best. In terms of reported physical symptoms, psychological symptoms, and activities, there were statistically significant differences between the scores of the control group and each of the experimental groups. Nonetheless, the total quality of life score showed no significant difference between the control group and the massage only group (t = 0.529, p = 0.60).
			Conclusions: When paired with aromatherapy inhalation, massage has a positive effect on physical, psychological symptoms, activities, and overall quality of life for cancer patients receiving early palliative care. Nurses and other healthcare providers are recommended to support programs that provide message therapy to reduce reported bodily symptoms, psychological problems, and limited activities among cancer patients.
2	Palliative Medicine	Does aromatherapy massage benefit patients with cancer attending a specialist palliative care day center?	A randomised controlled pilot study was carried out to examine the effects of adjunctive aromatherapy massage on mood, quality of life, and physical symptoms in patients with cancer attending a specialist unit. Participants were randomised to conventional day care alone or day care plus weekly aromatherapy massage using a standardised blend of oils for four weeks. At baseline and at weekly intervals, patients rated their mood, quality of life, and the intensity and bother of two symptoms most important to them. Forty-six patients were recruited to the study. Due to a large number of withdrawals, only 11 of 23 (48%) patients in the aromatherapy group and 18 of 23 (78%) in the control group completed all four weeks. Mood, physical symptoms, and quality of life improved in both groups. There was no statistically significant difference between groups in any of the outcome measures. Despite a lack of measurable benefit, all patients were satisfied with the aromatherapy and wished to continue. Whilst this pilot study has shown that a randomised controlled trial of complementary therapy is feasible, it has also identified several areas that would require further consideration when designing future studies, e.g., the recruitment and retention of appropriate numbers of patients and the outcome measures used.	2004	¹⁰
3	Cancers (Basel)	Aromatherapy in Palliative Care: A Single-Institute Retrospective Analysis Evaluating the Effect of Lemon Oil Pads against Nausea and Vomiting in Advanced Cancer Patients	Aromatherapy is regularly used in the University Hospital Krems’s palliative care unit. In a retrospective analysis, we investigated whether there were improvements in nausea and vomiting in patients with advanced cancers over a time span of 24 months. Data collection used the medical records of patients who were institutionally approved to receive routine aroma applications for alleviating nausea and vomiting. The efficacy of using lemon oil pads was tested with one-dimensional chi-squared tests. Sixty-six patients received 222 applications of lemon oil on cotton pads; no data were available for 17 applications. The adequate relief of nausea and vomiting was reported for 149 (73%) applications, whereas no symptom control was seen for 56 (27%) applications. For the 56 applications without symptom control, first- and second-line rescue medications were successful in 53 and 3 cases, respectively. The use of aromatherapy with lemon oil pads against nausea and vomiting was feasible for 73% of all applications. All patients who did not benefit from aromatherapy had effective symptom control with a rescue medication. Large randomised prospective trials are necessary to evaluate the benefit of the use of lemon oil pads against nausea and vomiting in patients with advanced cancer.	2022	¹¹
4	Journal of Pain and Symptom Management	Effect of Aromatherapy Massage on Quality of Sleep in the Palliative Care Ward: A Randomized Controlled Trial	Context: There is little evidence of the effectiveness of aromatherapy massage in palliative care despite its popularity.	2020	¹²
			Objectives: This study aimed to investigate the effects of a 30-minute single session of aromatherapy massage at night time on quality of sleep and fatigue in palliative care.
			Methods: A randomised controlled trial from January 2018 to March 2019. After being stratified by sex, participants were randomly assigned to an aromatherapy massage group and a control group. The effects of aromatherapy massage were evaluated on the massage day and the next day using the Richards-Campbell Sleep Questionnaire and the Brief Fatigue Inventory.
			Results: Of the 74 participants, data of 27 participants in the treatment group and 30 participants in the control group were analyzed. Analysis of covariance indicated that quality of sleep and fatigue did not improve owing to the aromatherapy massage, although usual fatigue in preceding 24 hours and enjoyment of life subscales of the Brief Fatigue Inventory showed signs of contribution (p = 0.07 and 0.09, respectively). Post hoc analyses indicated that higher age and performance status were factors with moderate correlation with better sleep (p = 0.03; r = 0.45 and p = 0.03; r = 0.40, respectively), and that older patients tended to experience greater improvement in fatigue (p = 0.02; r = −0.47).
			Conclusion: A single aromatherapy massage session is no more effective than not having a massage in improving sleep quality in palliative care settings. However, older patients and those in poor health conditions may benefit from aromatherapy massage.
5	International Journal of Nursing Practice	The effect of aromatherapy and massage administered in different ways to women with breast cancer on their symptoms and quality of life	The primary objective of this study was to assess the effect of aromatherapy and classical massage administered in various ways to breast cancer patients on their symptoms and quality of life. The sampling consisted of 280 patients. Quality of life and symptoms of the patients were evaluated once at baseline and then at week 6 and week 10 following the intervention. After intervention, the control group was observed to have lower total quality of life score and subdomain scores, whereas fragrance, massage, and aromatherapy massage groups had higher scores, and the increase was more obvious particularly in the patients in the aromatherapy massage group. Similarly, whereas psychological and physical symptoms were experienced more intensely in the control group, the severity of all the symptoms experienced by the other patients decreased at week 6 and week 10 as compared with baseline especially in the group that was administered massage with aromatherapy.	2014	⁵
6	Journal of Clinical Nursing	Experiences of aromatherapy massage among adult female cancer patients: A qualitative study	Aims and objectives: To explore the experiences towards aromatherapy massage use, and to examine the perceived benefits and adverse effects of aromatherapy massage among adult female cancer patients.	2017	¹³
			Method: A qualitative research design was used. Fifteen women with cancer were recruited for semi-structured interviews. Sample recruitment was undertaken through cancer self-help groups and referrals of a private aromatherapy clinic by convenience sampling. The interview data were analysed by thematic analysis.
			Results: All participants had a positive experience towards aromatherapy massage. The perceived benefits of aromatherapy massage included physical and psychological dimensions: overall comfort, relaxation, reduced pain, muscular tension, lymphoedema and numbness, improved sleep, energy level, appetite, and mood. Interestingly, a few participants reported that aromatherapy massage helped to enhance self-acceptance and coping with their altered torso. No adverse effects were reported. The findings focused on four main themes that emerged: (i) an immediate effect that brings all-round comfort and reconnection to daily life; (ii) a pleasurable moment to forget the disease with aroma as a booster; (iii) a pampering experience of being cared for with a sense of dignity preserved; and (iv) communicating with the failing body.
			Conclusions: This study contributed by providing a better understanding in aromatherapy massage from female cancer patients’ perspective which adds to the existing body of knowledge. The implications for nursing practice, education, and future research were suggested.
			Relevance to clinical practice: Aromatherapy massage seems to have both physical and psychological benefits for women with cancer. The findings elucidated a wide range of benefits that are perceived in such complex intervention, and the contextual factors that may influence these perceived benefits. This will inform future nurse-led quantitative research in the clinical setting. The study highlights the importance of touch toward a caring relationship and the provision of cancer care with a gender-specific approach. Exploring of the lived experience of aromatherapy massage and its meaning enables the healthcare professionals to gain insights into the needs, preferences, and values for cancer care among female cancer population. While nurses play a crucial role in collaborating with cancer patients in the choice of CAM therapies, nurses should advise them to attend practising aromatherapists with recognised training and competency who should be members of aromatherapy professional associations. As aromatherapy is an unregulated profession, nurses may also advise oncology patients on the international guideline and institutional policies for aromatherapy massage use in the hospital setting. Nurses may broaden the caring repertoire by expanding their knowledge and skills in aromatherapy massage such as understanding the basic essential oils pharmacology, massage skills and therapy efficacy for symptoms management in cancer care. Oncology clinicians and nurses should support and guide patients’ decision in the use of aromatherapy massage by providing evidence-based and comprehensive advice on the potential benefits, risks, and related safety issues.
			Keywords: Chinese; aromatherapy massage; cancer; experiences; oncology; qualitative; supportive care; symptom management; women.
7	Palliative Medicine	A randomised controlled trial of aromatherapy massage in a hospice setting	Research suggests that patients with cancer, particularly in the palliative care setting, are increasingly using aromatherapy and massage. There is good evidence that these therapies may be helpful for anxiety reduction for short periods, but few studies have looked at the longer term effects. This study was designed to compare the effects of four-week courses of aromatherapy massage and massage alone on physical and psychological symptoms in patients with advanced cancer. Forty-two patients were randomly allocated to receive weekly massages with lavender essential oil and an inert carrier oil (aromatherapy group), an inert carrier oil only (massage group) or no intervention. Outcome measures included a Visual Analogue Scale (VAS) of pain intensity, the Verran and Snyder-Halpern (VSH) sleep scale, the Hospital Anxiety and Depression (HAD) scale and the Rotterdam Symptom Checklist (RSCL). We were unable to demonstrate any significant long-term benefits of aromatherapy or massage in terms of improving pain control, anxiety, or quality of life. However, sleep scores improved significantly in both the massage and the combined massage (aromatherapy and massage) groups. There were also statistically significant reductions in depression scores in the massage group. In this study of patients with advanced cancer, the addition of lavender essential oil did not appear to increase the beneficial effects of massage. Our results do suggest, however, that patients with high levels of psychological distress respond best to these therapies.	2004	¹⁴
8	Journal of Clinical Oncology	Effectiveness of aromatherapy massage in the management of anxiety and depression in patients with cancer: a multicenter randomised controlled trial	Purpose	2007	¹⁵
			To test the effectiveness of supplementing usual supportive care with aromatherapy massage in the management of anxiety and depression in cancer patients through a pragmatic two-arm randomised controlled trial in four United Kingdom cancer centers and a hospice.
			Patients and Methods
			Two hundred eighty-eight cancer patients, referred to complementary therapy services with clinical anxiety and/or depression, were allocated randomly to a course of aromatherapy massage or usual supportive care alone.
			Results
			Patients who received aromatherapy massage had no significant improvement in clinical anxiety and/or depression compared with those receiving usual care at 10 weeks postrandomization (odds ratio [OR], 1.3; 95% CI, 0.9 to 1.7; p = 0.1), but did at 6 weeks postrandomization (OR, 1.4; 95% CI, 1.1 to 1.9; p = 0.01). Patients receiving aromatherapy massage also described greater improvement in self-reported anxiety at both 6 and 10 weeks postrandomization (OR, 3.4; 95% CI, 0.2 to 6.7; P = .04 and OR, 3.4; 95% CI, 0.2 to 6.6; P = .04), respectively.
			Conclusion
			Aromatherapy massage does not appear to confer benefit on cancer patients’ anxiety and/or depression in the long-term, but is associated with clinically important benefit up to 2 weeks after the intervention.

The studies included in this review encompass a diverse range of trial designs spanning eight trials. The participant count across these trials totaled 1162 individuals, with study samples varying from 46 to 280 participants. Aromatherapy was evaluated in all these trials: massage in seven and pads in one. Notably, three studies specifically investigated whether massage combined with aromatherapy provided more significant benefits than massage alone. The majority of these trials primarily focused on participants with cancer diagnoses, emphasizing the relevance of complementary therapies in oncological contexts. All studies were published in English, reflecting a common language of dissemination within this research domain. The follow-up time points after the intervention were predominantly immediate postintervention, focusing on short-term effects. Aromatherapy interventions were delivered through varied means, such as inhalation only or as part of a massage with essential oils, conducted in diverse settings, including participants’ homes or purpose-built units like hospices. Similarly, massage sessions varied in duration and frequency, often conducted in participants’ homes and administered by trained massage therapists or nurses. Across the studies, diverse scales were utilized for the outcome, and comparators ranged from usual care and placebo controls to different active interventions, providing a multifaceted landscape for evaluating the efficacy of these complementary therapies (Table 3).

Table 3.

Characteristics of Included Studies

Study	1	2	3	4	5	6	7	8
Design	True experimental, pretest–posttest group design	Randomized controlled trial conducted in a specialist palliative care setting	Retrospective analysis	Pragmatic, single-institute, randomized controlled study	Randomized controlled trial	Descriptive, exploratory, and qualitative in-depth semi-structured interview	Randomized Controlled Trial	Pragmatic, multicenter, two-arm, randomized, controlled trial
Sampling	A sample of 100 participants attending an oncology center	46 cancer patients attending daycare	66 adult patients	All 74 participants from the palliative care ward	280 Women with breast cancer undergoing chemotherapy	Convenience sampling from cancer self-help groups and referrals to a private aromatherapy clinic	Patients recruited from three specialist palliative care units within the South Thames region	Patients recruited from four cancer centers and one hospice in England between September 1998 and May 2002
Randomization	Participants were randomized into one of four groups using a computer-generated random table	1:1 randomization to either daycare plus weekly aromatherapy massage (aromatherapy group) or daycare alone (control group) for four weeks	Not applicable	Performed using permutated block randomization, stratified by sex	Random assignment of 280 eligible patients into four groups	Not applicable	Patients were randomly allocated to one of three groups	Randomly assigned using random number sequence, stratified by disease stage and trial center, and balanced in randomly sized blocks
Randomized method	Computer-generated random table	Block randomization to ensure balanced group numbers carried out independently of the research team	Not applicable	Computer-generated random number allocation	Not specified	Not applicable	Treatment allocation was concealed in a numbered opaque envelope, opened after baseline assessment.	Sealed, opaque envelopes with random allocation performed by the trial statistician
Inclusion Criteria	Participants aged 20–60 with second or third-stage cancer, receiving chemotherapy or radiation therapy more than a month after surgery, and may also be receiving hormone therapy.	Patients attending daycare, able to give informed consent, not participating in other studies, not too frail	All adult patients who gave consent for aroma care treatment against nausea and vomiting	Patients 18 years or older, diagnosed with advanced cancer, able to give informed consent and respond to questions	Non-pregnant, Turkish-speaking women, at least 18 years old, receiving chemotherapy for breast cancer	Women over 21 years of age, were able to communicate effectively in Cantonese and had used Aromatherapy Massage (ATM) to manage cancer symptoms.	Patients with a diagnosis of cancer and able to complete assessment scales	Patients diagnosed with cancer, estimated prognosis of more than three months, referred by a cancer health professional, clinical anxiety and/or depression according to DSM-IV criteria
Exclusion criteria	Excludes participants with cancer recurrence	Unable to give informed consent, participating in other studies, too frail	Not explicitly stated	Refusal to participate, allergies to essential oils or carrier oils, life expectancy of four days or less, past aromatherapy experience, new or dose changes in hypnosis treatments on the study day, steroid treatment changes within seven days before the study day, presence of lesions, tumors, inflammation, or open wounds in areas for aromatherapy massage	Stage IV cancer, use of anticoagulants, heart failure, cellulite, open wounds, fracture, epilepsy, hemorrhage, paraplegia, pacemakers, psychiatric problems	Not specified	Excluded if received aromatherapy, massage, chemotherapy, or radiotherapy within the previous month	Clinical concerns requiring psychiatric assessment, prescribed psychotropic medication or begun formal psychological intervention within three months of baseline assessment
Instruments	Modified Rotterdam Symptom Checklist (RSCL) divided into two parts: sociodemographic and clinical data and symptom quantification	-0–7 numerical rating scales for intensity and bother of two physical symptoms chosen by patients-Overall quality of life assessed using the Measure Yourself Medical Outcome Profile (MYMOP)-Profile of Mood State (POMS) questionnaire with six subscales	Data collected from medical records, access-restricted system at UHK	The Japanese version of the Richards-Campbell Sleep Questionnaire (RCSQ) and the Brief Fatigue Inventory (BFI)	Questionnaire, Quality of Life Scale, Rotterdam Symptom Checklist	Semi-structured interview guide	Visual Analogue Scale (VAS), Modified Tursky Pain Descriptors Scale, Verran and Snyder-Halpern (VSH) sleep scale, Hospital Anxiety and Depression (HAD) scale, Rotterdam Symptom Checklist (RSCL)	Modified Diagnostic and Statistical Manual of Mental Disorders criteria, Structured Clinical Interview, State Anxiety Inventory, Center for Epidemiological Studies Depression Scale, European Organization for Research and Treatment of Cancer QLQ-C30
Intervention	Group 1: Standard hospital careGroup 2: Hand massage with almond oilGroup 3: Hand massage with lavender oilGroup 4: Aromatherapy with lavender oil	Weekly aromatherapy massage for four weeks alongside daycare	Aromatherapy using lemon oil pads for nausea and vomiting in palliative care patients	Aromatherapy massage performed at least three days after patient transfer to the ward, between 8:00 pm and 9:00 pm, using blended oils (lavender, orange, or a mixture), performed by a certified therapist	Fragrance Group, Classical massage group, Aromatherapy massage group, Control group	ATM performed by a registered nurse aromatherapist using pure essential oils diluted in base oils	1) Massage with lavender essential oil and inert carrier oil (aromatherapy group)2) Massage with inert carrier oil only (massage group)3) Control group-no message	Aromatherapy massage-4-week course of weekly, 1-hour sessions, 20 essential oils, agreed on treatment protocol by participating therapists
Massage procedure	Same for all groups, involving stroking and rubbing with 5 ml sweet almond carrier oil for 30 minutes three times a week	Administered by a qualified aromatherapist in a complementary therapy unit, using a blend of 1% lavender and chamomile in sweet almond carrier oil; patients chose the area for massage (back, neck, shoulders, or hand)	Not applicable	Effleurage massage with mild-to-moderate pressure using the flat portion of the palms from palm to elbow and sole of foot to knee	Classical massage with olive oil applied to legs, arms, feet, and hands; Aromatherapy massage with aromatic oils	Full body massage (Swedish style massage) with attention to specific body areas based on individualized needs	Standardized 30-minute back massage weekly for four weeks	Aromatherapists prescribed the treatment based on individual patient needs within the agreed protocol
Aromatherapy procedure	Lavender oil inhalation, sprayed into the room four times per day or placed on a sniff stick for severe symptoms	-A blend of 1% lavender and chamomile in sweet almond carrier oil-Patients chose between back, neck, shoulders, or hand massage for 30 minutes weekly for four weeks	Lemon oil applied on cotton pads, clipped on clothes or given to patients as needed.	Used lavender, orange, or a mixture of the two aroma oils; therapist certified by the International Federation of Professional Aromatherapists and Aroma Environment Association of Japan.	Essential oils (lavender, mint, chamomile, jasmine, violet, rosemary, eucalyptus) diluted 1.1% with sweet almond carrier oil, applied three times a week for one month.	Use of pure essential oils diluted in base oils during the massage	Lavender essential oil mixed with sweet almond oil (1% dilution)	A 4-week regimen of weekly, 1-hour aromatherapy massage sessions, following a treatment protocol with 20 essential oils and prescribed techniques.
Essential oil used	Lavender	Lavender and chamomile	Lemon	Lavender or orange or a mix of both	Lavender, mint, chamomile, jasmine, violet, rosemary, eucalyptus	Not mentioned	Lavender	The therapists prescribed the treatment they considered most appropriate to individual patients from the 20 selected essential oils
Evaluation phase	Done two months after the intervention phase using the RSCL tool for reevaluation of participants’ quality of life	Baseline and weekly intervals for four weeks	Retrospective evaluation of medical records	Two consecutive days-study day and the next day; monitoring for adverse effects for one week after the study day	Weeks 6 and 10	15 semi-structured interviews were conducted in a private room	Baseline assessment and final assessment in the week after the last message	Baseline, six weeks, and ten weeks post-randomization
Outcome measures	-Physical symptoms, psychological symptoms, self-care activities, and overall quality of life	-Change in POMS, physical symptoms, and quality of life expressed as slopes using linear regression	-Efficacy of lemon pads-Need for rescue medication-Causes of nausea and vomiting.	RCSQ for sleep quality (perceived sleep depth, sleep latency, awakenings, return to sleep, perceived sleep quality) and BFI for fatigue severity and interference items	Quality of life (subdomains and overall), Rotterdam Symptom Checklist (psychological, physical, overall)	Participants’ experiences, perceived benefits, and adverse effects of ATM	Pain intensity (VAS), Modified Tursky Pain Descriptors Scale, VSH sleep scale, HAD scale, RSCL	Primary: Change in anxiety and/or depression between full case and borderline or noncase at ten weeks post-randomization; Secondary: Various measures including self-reported anxiety, depression, fatigue, pain, nausea, vomiting, and global quality of life
Results	Significant improvements were observed in physical and psychological symptoms, self-care activities, and overall quality of life in the massage-only, massage with lavender oil, and combined aromatherapy groups	46 patients were recruited, 23 in each arm, with 11 in the aromatherapy group and 18 in the control group completing the four weeks. There were no significant differences in outcomes between the groups. Aromatherapy well-received, with satisfaction and a desire to continue among patients	-The lemon oil pads were effective in 73% of the cases-Need for rescue medicine was only required in 27% of the cases-Causes of Nausea and Vomiting had higher efficacy in non-gastric causes and less efficient in cases involving visceral or serosal problems	There were no statistical differences between groups in baseline demographics; no significant improvement in sleep quality or fatigue with aromatherapy massage; post hoc analysis suggested favorable factors (older age, higher performance status)	Considerable improvement in quality of life and reduction in symptoms in intervention groups, with aromatherapy massage showing the most prominent effect	Positive experiences were reported by all 15 participants, including overall comfort, relaxation, reduced pain, improved sleep, energy level, appetite, and mood. Four main themes emerged: Immediate comfort, Pleasurable moments with aroma, Pampering experience with dignity, Communicating with the failing body	No significant changes in pain scores or descriptors; Significant reduction in pain VAS scores in aromatherapy and combined massage groups after the second treatment	63% of all patients at ten weeks post-randomization had improvement in anxiety and/or depression; significant improvement in self-reported anxiety for the aromatherapy massage group at 6 and 10 weeks post-randomization
Conclusion	The study concludes that the interventions positively impacted the participants’ quality of life.	Feasibility of applying randomized controlled trial design to study aromatherapy in a specialist palliative care setting demonstrated; challenges in recruitment and retention; multicenter trials advisable for sufficient power	Aromatherapy using lemon oil pads showed effectiveness in reducing nausea and vomiting in palliative care patients.	A single night-time aromatherapy massage did not show significant advantages over no massage in improving sleep quality for palliative care patients; despite this, the elderly and patients with poor health conditions might benefit.	Aromatherapy massage provides long-term improvement in quality of life and symptoms; other interventions also have positive effects.	Female cancer patients perceived Aromatherapy Massage (ATM) as a positive experience with immediate changes and no side effects. The therapy was beneficial for managing physical and psychological symptoms, providing a holistic and individualized approach with dignity-enhancement effects. The study suggests the potential benefits of ATM as an adjunct therapy for women with cancer.	-Aromatherapy and massage may have a short-term beneficial effect on pain.-Potential improvement in sleep quality-No sustained benefit in anxiety reduction-Some improvement in depression scores, especially in the massage group	Aromatherapy massage showed short-term improvement in clinical anxiety and/or depression, especially in anxiety; benefits need to be compared with psychological interventions for this patient group.
Adverse effects	Not reported	One patient withdrew owing to a rash; otherwise, no serious adverse events were reported.	Not reported	Not reported	Not reported	Not reported	Not reported	Not reported

The reviewed studies exhibit design, sampling, and outcome variations while exploring aromatherapy in palliative care. RCTs (Studies 2, 4, 5, 8) employ computer-generated tables or block randomization methods. Samples, varying in size, are drawn from diverse cancer care settings, including daycare, oncology centers, and self-help groups. Inclusion criteria commonly involve age restrictions, cancer diagnoses, and consent capability. Exclusion criteria contribute to heterogeneity, ranging from participation in other studies to specific medical conditions. Aromatherapy interventions, predominantly involving massage with essential oils like lavender and chamomile, are conducted weekly over specified durations. Outcome measures assess changes in physical and psychological symptoms, sleep quality, and anxiety/depression reduction. Positive effects on quality of life, symptom reduction, and patient satisfaction are commonly reported across studies. The conclusions generally emphasize the positive impact of interventions on participants’ well-being. Despite shared themes, distinctions exist in study settings, designs, and specific criteria, highlighting the nuanced landscape of aromatherapy research in palliative care.

Risk of bias

The assessment of the risk of bias across the included studies demonstrates overall favorable methodological adherence, portraying a considerable level of rigor in most studies (Fig. 2). The majority maintain a low risk across various key domains, signaling robust randomization, blinding, and data handling practices. However, a few studies exhibit moderate risks, notably in domains associated with blinding procedures and potential biases, indicating some concerns regarding the reliability of these specific study aspects. Only five studies adequately describe methods to conceal group allocation, by using, for example, sealed packs and opaque envelopes.^{9,10,12,14,15} Two studies lacked explicit information regarding which essential oils were used, resulting in a moderate overall risk.^13,15 While most studies maintain a solid methodological foundation, those with moderate risks emphasize the need for enhanced reporting and more transparent methodological descriptions to facilitate a more comprehensive assessment of potential biases.^11,13,15

FIG. 2.

Risk of bias.

Discussion

The systematic review of eight diverse studies exploring the impact of aromatherapy on individuals diagnosed with cancer reveals promising insights into the potential benefits of this complementary intervention. The studies, employing various designs, interventions, and outcome measures, collectively contribute to a nuanced understanding of aromatherapy’s effects in the oncology setting.

Positive impacts on quality of life

Several studies, particularly those utilizing aromatherapy massage (ATM), reported positive impacts on physical and psychological symptoms, self-care activities, and overall quality of life. The improvement observed in Study 1 across multiple domains suggests a potential holistic benefit of aromatherapy interventions, reinforcing the notion that these interventions may contribute positively to the well-being of cancer patients.

Feasibility challenges and retention issues

Study 2, conducted in a specialist palliative care setting, highlights the challenges in applying a RCT design to study aromatherapy. The feasibility of such an approach is demonstrated, but the study also underscores the importance of addressing recruitment and retention challenges, advocating for multicenter trials to ensure sufficient statistical power and generalizability.

Efficacy in nausea and vomiting reduction

The efficacy of aromatherapy using lemon oil pads in reducing nausea and vomiting in palliative care patients (Study 3) presents a specific application of aromatherapy with potential clinical relevance. The reported 73% efficacy and patient satisfaction suggest a practical avenue for managing distressing symptoms in this population.

Sleep quality considerations

Study 4, focusing on the impact of a single night-time ATM on sleep quality, provides nuanced insights. While the intervention did not exhibit significant advantages over no massage for the overall cohort, post hoc analysis suggests potential benefits for specific subgroups, such as elderly patients and those with poor health conditions. This highlights the importance of considering individual characteristics in tailoring aromatherapy interventions.

Differential effects across cancer types

The variation in outcomes across cancer types, as seen in Study 5, underlines the need for personalized approaches in aromatherapy interventions. The significant improvement in quality of life and symptom reduction in breast cancer patients undergoing chemotherapy implies potential differential effects based on the type and stage of cancer.

Patient perspectives in qualitative study

The qualitative study (Study 6) provides valuable insights into patient perspectives. Female cancer patients perceived ATM positively, reporting immediate changes and no side effects. The emergent themes underscore the multifaceted impact of aromatherapy on patients, ranging from immediate comfort to dignity enhancement.

Short-term benefits in pain and psychological well-being

Studies 7 and 8, employing a pragmatic approach and RCT design, respectively, converge on the short-term benefits of ATM in addressing clinical anxiety and/or depression, particularly in anxiety. While pain and sleep quality improvements are noted, sustained effects and comparative assessments with psychological interventions warrant further exploration.

Individualized treatment

Study 8, distinguished in Table 3 for its incorporation of individualized treatment plans in essential oil selection and massage techniques, offers valuable insights into the potential benefits of personalized aromatherapy interventions. Including 20 selected essential oils, with therapists tailoring treatments based on individual patient needs within an established protocol, underscores the importance of a patient-centric approach. The positive outcomes observed in this study, particularly in terms of symptom reduction and enhanced quality of life, suggest that individualization plays a crucial role in optimizing the therapeutic effects of aromatherapy. This finding aligns with the discussion in Differential effects across cancer types section, emphasizing the need for personalized approaches to aromatherapy interventions, as demonstrated by the variation in outcomes across different cancer types. The success of individualized treatment plans in Study 8 prompts consideration of future research directions that specifically explore the impact of tailored aromatherapy on symptom management, quality of life, and overall well-being, considering the diverse landscape of cancer types and stages.

Adverse effects considerations

Adverse effects were not explicitly mentioned in the majority of studies, with only one withdrawal owing to a rash reported in Study 2. This highlights aromatherapy’s generally favorable safety profile, but the limited reporting necessitates a cautious interpretation.

In reviewing the essential oils utilized across the studies in Table 3, it is noteworthy that various aromatic compounds were employed to implement aromatherapy interventions. Lavender was a commonly employed essential oil, featured in Studies 1, 2, 4, 6, and 7, highlighting its widespread recognition for potential therapeutic effects. Lemon oil, the focus of Study 3, demonstrated efficacy in reducing nausea and vomiting in palliative care patients, while Study 8 stands out for its unique approach. In Study 8, therapists individually tailored treatments using what they considered the most appropriate essential oil from 20 options. This approach signifies a departure from a single essential oil and emphasizes a personalized treatment strategy. Other studies incorporated a range of essential oils, including chamomile, orange, mint, jasmine, violet, rosemary, and eucalyptus. The diversity in essential oil selection may contribute to the variations in outcomes observed across studies, emphasizing the importance of considering individual essential oils’ specific properties and effects in aromatherapy interventions.

In addressing the efficacy of aromatherapy as a complementary intervention within palliative care, this review consolidates evidence supporting its multifaceted impact on symptom management and the overall quality of life (RQ1). Across diverse studies, aromatherapy demonstrates promising efficacy in alleviating a spectrum of symptoms commonly encountered in palliative care settings. Specifically, findings reveal its notable effectiveness in ameliorating pain, anxiety, nausea, and sleep disturbances, offering a multidimensional approach to symptom relief. Studies consistently underscore the potential of aromatherapy in mitigating pain perception, reducing anxiety levels, easing nausea-related distress, and improving sleep quality. However, while the overall trend suggests positive outcomes, variations in methodologies, intervention protocols, and outcome measures present challenges in drawing definitive conclusions. The heterogeneity across studies necessitates a cautious interpretation of findings and highlights the need for more standardized approaches and larger-scale trials to establish robust evidence regarding the specific symptom-relieving capacities of aromatherapy within palliative care (RQ2). Addressing these research gaps could provide tailored insights into the application of aromatherapy for different symptoms, enhancing its clinical utility in holistic patient care.

Conclusion

The reviewed evidence suggests the potential of aromatherapy, particularly ATM, as a valuable adjunct to conventional cancer care and palliative support. However, the observed variability in methodologies, interventions, and outcomes among the studies underscores the ongoing need for cautious interpretation. The identified areas of methodological concerns, particularly in blinding and reporting, emphasize the necessity for standardized approaches in future investigations. Larger-scale trials with more rigorous methodologies are essential to better understand aromatherapy’s efficacy and safety within palliative care contexts. Future research should prioritize standardized protocols tailored to specific cancer types and integrate patient perspectives to enhance intervention tailoring and overall efficacy.

It is imperative to extend the discussion beyond the confines of oncology and consider the applicability and generalizability of aromatherapy to a broader spectrum of palliative care populations. While the current review primarily delves into the impact of aromatherapy within the context of cancer care, recognizing its potential benefits and the inherent variability in study methodologies, interventions, and outcomes prompts a broader reflection on its relevance to diverse palliative care scenarios. The observed variability across studies necessitates future research exploring aromatherapy’s efficacy in addressing symptoms and enhancing the quality of life in palliative care populations with various medical conditions. Acknowledging the potential versatility of aromatherapy as a holistic intervention, the discussion should underscore the need for rigorous investigations in nononcological palliative care settings. This approach ensures a comprehensive understanding of aromatherapy’s effectiveness and aids in formulating tailored interventions for individuals receiving palliative care, regardless of their specific medical context.

Footnotes

Authors’ Contributions

S.G.: Conceptualization, Methodology, Writing—Original Draft, Visualization, Supervision, and Project administration; S.G. and R.S.M.: Investigation, Data Curation, Resources, and Formal Analysis; R.S.M.: Validation; S.G., R.S.M., and P.M.: Writing—Review & Editing.

Data Sharing Statement

Data supporting the findings and conclusions are available upon request from the corresponding author.

Funding Information

This research received no specific grant from public, commercial, or not-for-profit funding agencies.

Author Disclosure Statement

No competing financial interests exist.

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