Aromatherapy can be considered a branch of phytotherapy that uses essential oils, the volatile and strongly smelling substances of plants. The oils are usually extracted by steam distillation, which once cooled allows the separation of the essential oil from the water.
In the case of the epicarp of the fruits of the genus cold pressing is also used. Aromatic substances extracted with other methods (extraction with organic solvents, extraction with supercritical fluids) are not considered by all authors as essential oils.
The so-called essential oils obtained by dissolving resins and oleoresins in alcohols are actually defined as resinoids. The article: Effects of aromatherapy on anxiety: A meta-analysis of randomized controlled trials, published by Journal of affective disorders gives interesting answers on this topic.
Below you can read an abstract of the article:
"Scope: The effects of aromatherapy on relieving anxiety were controversial. The purpose of this meta-analysis was to evaluate the effects of aromatherapy on anxiety in patients.
Methods and results: We searched randomized controlled trials (RCTs) about aromatherapy on decreasing anxiety on PUBMED, WEB OF SCIENCE (January 1990 to October 2019), COCHRANE LIBRARY, EMBASE (updated to October 2019), and the Chinese databases CNKI, WanFang and CBMD.
Twenty-five articles (Thirty-two trials) were included in this meta-analysis. The data of scale scores of Spielberger State-Trait Anxiety Inventory (STAI) were extracted. The pooled results demonstrated that inhalation and massage aromatherapy significantly decreased anxiety levels in different conditions.
The weighted mean difference was -5.16 for State Anxiety Inventory (SAI) (95% CI: -5.78, -4.55, p <0.001) and -2.85 for Trait Anxiety Inventory (TAI) (95% CI: -3.95, -1.75, p <0.001). No side effects were mentioned in all of studies.
Conclusion: The meta-analysis suggested that aromatherapy with different essential oils could alleviate anxiety significantly no matter the reason of anxiety. However, the proper dosage of essential oils needs further research."