The anxiolytic effects of Lavandula angustifolia (lavender): An overview of systematic reviews

Introduction: Aromatherapy and decoctions of lavender have been traditionally used for their anxiolytic harboring-soothing effects without proper evidence. This study aims to systematically identify and appraise systematic reviews on the anxiolytic effects of Lavandula angustifolia (lavender).Methods: The study protocol was published in PROSPERO (CRD42021279573). ISI Web of Science, Scopus, PubMed, Embase, Cochrane Library, CINAHL, Google Scholar, and PROSPERO were searched up to August 2022 without any limitation for systematic reviews studying the anxiolytic effects of lavender in humans. The report from each study as whether or not lavender was anxiolytic was considered the primary outcome. The AMSTAR II was utilized for the quality assessment.Results: Thirty systematic reviews met the inclusion criteria, fifteen of which conducted meta-analyses. All studies were published after 2010 and reported promising effects through different methods of lavender administration-namely: inhalation, massage, and oral routes-on anxiety relief. Oral doses of 80 mg and 160 mg were both effective, the higher dose being more efficient. The studies were conducted on various subjects, including preoperative patients, cardiovascular patients, hemodialysis patients, cancer patients, dental patients, and women in pre-labor. When assessed by AMSTAR II, four studies were of high quality, one had medium quality, and the rest were of low or critically low quality. No major adverse event was reported.Conclusions: Lavender has shown promising potential for anxiety in various settings. Lavender was effective when inhaled, used as a massage oil, or taken orally. The oral route was the preferred long-term option and inhalation was recommended for the short term.