Effects of aromatherapy on nausea and vomiting in patients with cancer: A systematic review and meta-analysis of randomized controlled trials

Background: and purpose: Aromatherapy offers a low-risk solution for effectively managing common nausea and vomiting in cancer patients. This systematic review and meta -analysis aimed to assess its impact on these symptoms to facilitate practical guidelines establishment. Methods: PubMed, Web of Science, Cochrane Library, MEDLINE, CINAHL, and Embase were searched for articles published until April 30, 2023. Inclusion criteria were randomized controlled trials (RCTs) on the effect of aromatherapy on nausea and vomiting in patients with cancer (age >= 18 years). The effect size was calculated using standardized mean differences (SMDs) with a random effects model. Subgroup analyses, meta -analysis of variance, and meta -regression were performed using the "meta" package in R version 4.0.2. Heterogeneity was assessed using I2 statistics. Sensitivity and publication bias analyses were performed; two reviewers independently assessed risk of bias using Cochrane's risk -of -bias tool 2.0. Results: Twenty-five RCTs across 10 articles revealed that aromatherapy reduced overall nausea and vomiting in patients with cancer with significant efficacy (SMD = -0.81, 95 % confidence interval [CI]: -1.11 to -0.52). Furthermore, aromatherapy reduced nausea (SMD = -0.85, 95 % CI: -1.23 to -0.46) and combined nausea and vomiting (SMD = -1.08, 95 % CI: -1.68 to -0.47), but not vomiting alone (SMD = -0.24, 95 % CI: -1.03 to 0.55). Inhalation and massage yielded positive results, especially in chemotherapy-induced cases; peppermint oil was particularly successful. Conclusion: Our findings underscore aromatherapy's value in managing cancer treatment-associated nausea and vomiting. Conclusive evidence on aromatherapy-led nausea reduction is lacking due to limited RCTs; research is warranted for robust conclusions.