Benefit of inhalation aromatherapy as a complementary treatment for stress and anxiety in a clinical setting - A systematic review

The purpose of this systematic review is to ascertain the impact of inhalation aromatherapy on stress and anxiety in clinical settings.

A search strategy was developed using various databases. Randomised Controlled Trials (RCTs) as well as single and double-blind pilot clinical studies (non-RCT) using inhalation aromatherapy with an essential oil blend or a single essential oil were examined. All studies included a control intervention and use of a validated measurement tool. The time period under review was years 2000-2021. Due to the high level of heterogeneity and element of bias, a narrative synthesis was conducted.

The search strategy initially retrieved 628 studies and through application of the selection criteria and the removal of duplicates, 76 studies were selected for review with a total of 6539 patients. In 42% of the RCTs, physiological measures including vital signs and/or salivary cortisol were used in addition to questionnaires. Over 70% of the studies reported a positive effect on anxiety levels in the aromatherapy intervention groups compared with the control. However, in many cases this is limited by the absence of safety data, imprecise reporting of plant species and dosage of essential oil.

Inhalation aromatherapy has the potential to reduce stress and anxiety with data emerging to further support this result across a wide modality of clinical treatments. However, there is a clear need for the development of standard protocols for research in this area, generating measurable results which will create the opportunity for more rigorous evidence-based outcomes.