Aromatherapy is the field of herbal medicine that uses essential oils distilled from flowers, roots, and herbs and other plant compounds to promote physical and psychological well-being. Essential oils are absorbed into the body in different ways, with the inhaled and topical routes being the most widely used. The aim of this review was to critically evaluate and synthesize the available scientific evidence on the efficacy and safety of aromatherapy for the management of any therapeutic indication. This report was requested by the Spanish Ministries of Health and Science and Innovation.

An overview of systematic reviews (SRs) was performed. The MEDLINE, Embase, CINAHL, and PsycINFO databases were searched for literature published from January 2006 to August 2021. SRs reporting the efficacy and safety of aromatherapy were included. We applied no restrictions in terms of administration route or essential oil used. Two reviewers independently performed screening and selection, data extraction, and quality assessment.

We included 74 SRs covering a wide variety of populations and settings. The most reported outcome was anxiety, followed by pain, and the most commonly used essential oil was lavender. Fifteen SRs reported mild adverse events with aromatherapy. Only 11 SRs assessed the certainty of evidence using the GRADE approach. Aromatherapy reduced heart rate and likely reduces anxiety and breathing rate in patients with cardiovascular diseases. Aromatherapy probably also reduces pain in women with primary dysmenorrhea. Additionally, it may reduce blood pressure, acute pain, subjective stress, and the need for antiemetic drugs after surgical procedures. However, the evidence was very uncertain regarding the effect of essential oils on anxiety, pain, and quality of life in patients with cancer, anxiety and pain after a caesarean section, and dental anxiety.

Aromatherapy may be useful for managing psychological and physical symptoms in different settings. However, the conclusions of this review are not definitive because of the moderate to high risk of bias in many of the primary studies included in the SRs.