The best route of administration of lavender for anxiety: a systematic review and network meta-analysis

Background: There is preliminary evidence for lavender as an anxiolytic agent through various routes of administration. Our goal is to elucidate the best route of administration for lavender as a treatment for anxiety. Methods: Thirteen electronic search engines were systematically scanned for relevant publications. The relevant articles were included after the title and abstract screening followed by the full-text screening. This study included randomized control trials reporting lavender for the treatment of anxiety. The protocol was registered in PROSPERO (CRD42017076711). Frequentist network meta-analysis and Bayesian meta-regression were conducted to report the best treatment modality and the effect of covariates on the effectiveness as an anxiolytic. Treatment arms were ordered according P-scores, where higher P-score indicates better treatment choice. Results: Forty studies were eligible for qualitative analysis, and 32 were included in quantitative analysis. Lavender aromatherapy was the best approach for the treatment of anxiety among other lavender modalities at the first week recording [Standardized Mean Difference (SMD)=-0.57, 95% CI (-1.14-0.01), Pscore =0.72], in addition to achieve at the first time points [SMD=-0, 95% CI (-0.97.-0.16), Pscore =0.69], compared to placebo; however, lavender massage along with foot bath were found to be the most efficacious for anxiety treatment at the study endpoint [SMD=-1.10, 95% CI=(-7.41. 5.21), Pscore =0.65]. Furthermore, network meta-regression revealed that the duration of therapy influenced treatment, suggesting Silexan (oral lavender) 80 mg (first rank probability=.116) as the favorable option for anxiety in long-term treatment. Conclusions: Lavender aromatherapy is, clinically, superior in short-duration, while Silexan (oral lavender) 80 mg is preferable for long-term treatment of anxiety.