Systematic Review and Meta-analysis of Lavender for Anxiety PDF Free Download
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File: ■ Lavender (Lavandula spp., Lamiaceae)
■ Anxiety
■ Systematic Review/Meta-analysis
HC 121951-631
Date: December 31, 2019
RE: Systematic Review and Meta-analysis of Lavender for Anxiety
Donelli D, Antonelli M, Bellinazzi C, Gensini GF, Firenzuoli F. Effects of lavender on
anxiety: A systematic review and meta-analysis. Phytomedicine. September 26,
2019;65:153099. doi: 10.1016/j.phymed.2019.153099.
Worldwide, up to 15% of the general population are affected by anxiety disorders.
Lavender (Lavandula spp., Lamiaceae) flower essential oil is a traditional remedy for
anxiety with demonstrated anxiolytic and sedative properties. The purpose of this
systematic review and meta-analyses was to evaluate the effect of lavender on anxiety
and anxiety-related disorders.
The study was conducted in accordance with the Preferred Reporting Items for
Systematic Reviews and Meta‐Analyses (PRISMA) guidelines. PubMed, Scopus, Web of
Science, Cochrane Library, EMBASE, and Google Scholar were searched from
inception up to November 2018 using the following terms: lavender, lavandula, Silexan,
anxiety, anxious, and anxiolytic. Included in the systematic review were randomized
controlled trials (RCTs) and non-randomized studies (NRS) evaluating lavender (any
species, any preparation form, any route of administration) for anxiety using any type of
comparator and a validated instrument to assess anxiety. Exclusion criteria were as
follows: animal or in in vitro studies, sample size unclear or unspecified, a blend of
lavender and other herbs of unclear composition was assessed, proportion of lavender
in the blend was not reported, lavender did not account for the majority of the blend
composition, and essential data were missing. Risk of bias (RoB) was assessed with the
Cochrane Collaboration RoB tool.
A total of 90 articles met the systematic review criteria, including 65 RCTs (n = 7993
participants) and 25 NRS (n = 1200 participants). The characteristics of the included
RCTs were summarized as follows: mean sample size was 90 participants (range 13 to
597); the most common route of administration was inhalation/aromatherapy (49 RCTs),
followed by topical (10 RCTs) and oral (6 RCTs); controls included placebo, usual care,
no intervention, and positive control; and the most commonly used outcome measures
were the State Trait Anxiety Inventory (STAI), Zung Self Rating Anxiety Scale (Zung
SAS), and Hamilton Anxiety Rating Scale (HAMA). A single, acute dose of lavender was
P.O. Box 144345 Austin, TX 78714-4345 512.926.4900 Fax: 512.926.2345 www.herbalgram.org
HerbClip™
Mariann Garner-Wizard Shari Henson Heather S Oliff, PhD
Samaara Robbins Gavin Van De Walle, MS, RD, LN
Executive Editor – Mark Blumenthal Managing Editor – Lori Glenn
Consulting Editors –Thomas Brendler, Meghan Henshaw, Allison McCutcheon, PhD, Kristen McPhee, MSciTH,
Beth Quintana, ND, Carrie Waterman, PhD
evaluated in 38 RCTs, and chronic lavender treatment was evaluated in 27 RCTs. The
most commonly evaluated lavender species was L. angustifolia.
Considering performance bias as the key domain, the overall quality of the evidence was
low with ~89% of the RCTs characterized by a high RoB. When performance bias was
considered as a non-key domain, 71% of the RCTs had a high overall RoB. Qualitative
synthesis of the included studies revealed 54 RCTs and 17 NRS reported lavender had
a beneficial effect on anxiety. Fifty-four RCTS found lavender significantly improved
anxiety compared with baseline or control (P < 0.05), 44 RCTs indicated lavender
significantly improved anxiety compared with the control (P < 0.05), and 11 RCTs
concluded lavender had no significant benefit. Seven studies reported adverse events
(AEs), which included headaches, palpitations, infections, and gastrointestinal disorders.
No serious AEs were reported.
Meta-analyses
For the meta-analyses, the following PICOS (population, intervention, comparator,
outcomes, and study design) inclusion and exclusion criteria were applied: (P)
population included patients with anxiety, involved in an anxiety-inducing setting or
undergoing an anxiety-inducing activity; (I) intervention was oral administration of
Silexan (proprietary, standardized lavender essential oil product manufactured by Dr.
Willmar Schwabe GmbH & Co. KG; Karlsruhe, Germany), lavender essential oil (LEO)
inhalation, or massage with LEO; (C) comparison with usual care, no intervention, sham
intervention or placebo, or massage without LEO; (O) outcome was anxiety measured
with validated scales (systolic blood pressure [SBP] was also considered as a
physiological measure which indirectly estimates anxiety levels); (S) study design was
randomized clinical trial (RCT). A total of 37 RCTs met these PICOS criteria and were
included in the following seven meta-analyses.
Meta-analysis of five RCTs (n = 1173 participants) evaluating the effect of 80 mg/day
of Silexan on anxiety measured with the HAMA indicated Silexan significantly
reduced anxiety compared to placebo (P = 0.004).
Meta-analysis of three RCTs (n = 451 participants) assessing the effect of 80 mg/day
of Silexan on anxiety measured with the Zung SAS indicated Silexan significantly
reduced anxiety compared to placebo (P = 0.02).
Meta-analysis of 12 RCTs (n = 901 participants) evaluating the effect of LEO
inhalation on state anxiety measured with the STAI-S indicated lavender significantly
reduced anxiety compared to the controls (P = 0.0006). Subgroup analyses of
situations inducing high-anxiety and mild-anxiety revealed that in both cases
lavender significantly reduced anxiety compared to the controls (P = 0.04 and P =
0.06 respectively).
Meta-analysis of four RCTs (n = 196 participants) assessing the effect of LEO
inhalation on trait anxiety measured with the STAI-T indicated lavender significantly
reduced anxiety compared to the controls (P = 0.01).
Meta-analysis of six RCTs evaluating the effect of LEO inhalation on SBP values
compared to no intervention or to sham intervention indicated lavender had no
significant effect.
Meta-analysis of 24 RCTs (n = 1682 participants) assessing the effect of LEO
inhalation on anxiety measured with any validated scale indicated lavender
significantly reduced anxiety compared to the controls (P < 0.0001). Subgroup
analyses showed lavender significantly reduced anxiety compared to the controls in
high-anxiety situations (P < 0.0001) but not in mild-anxiety situations.
Meta-analysis of six RCTs (n = 448 participants) evaluating the effect of LEO
massage on anxiety measured with any validated scale compared to other physical
therapies or usual care indicated lavender significantly reduced anxiety compared to
the controls (P < 0.001), and this effect was maintained in the subgroup analysis of
high-anxiety situations.
In summary, the meta-analyses indicate that oral Silexan and LEO inhalation
significantly reduce anxiety compared to controls. Massage with LEO also appears to
reduce anxiety; however, further RCTs are needed to demonstrate the benefit is due to a
specific effect of lavender. The limited safety data indicate lavender is well-tolerated with
no serious adverse effects. Acknowledged limitations include the low quality of
evidence/high RoB of the included RCTs, and the heterogeneity of the study designs.
"Further high quality RCTs with more homogeneous study designs are needed to
confirm these findings. [S]ince treatments with lavender essential oil generally seem
safe, and, in the case of inhalation, also simple and inexpensive, they are a therapeutic
option which may be considered in some clinical contexts," the authors conclude.
—Heather S. Oliff, PhD
Referenced article can be accessed at
https://www.researchgate.net/publication/336065685_Effects_of_lavender_on_anxiety_A_systematic_revie
w_and_meta-analysis.
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