By Ingrid Martin, MD
Fellow in Integrative Medicine,
Department of Family Medicine,
Maine Medical Center,
SYNOPSIS: In a randomized double-blind study funded by the Schwabe company to test its own products, oral administration of lavender essential oil was demonstrated to be a better treatment of general anxiety disorder than SSRIs or placebo.
SOURCE: Kasper S, et al. Lavender oil preparation Silexan is effective in generalized anxiety disorder — a randomized, double-blind comparison to placebo and paroxetine. Int J Neuropsychopharmacol 2014;17:859-869.
This study was conducted to test the effect the oral herbal concoction Silexan, a lavender essential oil, can have in relieving anxiety. A randomized, double-blind, two-stage trial, the study treated 536 patients between ages 18 and 65, spanning 57 psychiatric and general practices in Germany. All met or exceeded the DSM-IV criteria for general anxiety disorder, and had been suffering from GAD for an average of 2.5 years. The study excluded patients with severe depression, substance abuse or other serious neurological and mental disorders like schizophrenia. Each treatment group was comparable to each other at baseline.
After a screening and washout period of a week, participants were randomized into groups each receiving ten weeks of a different treatment. The four treatments were 80 mg of Silexan, 160 mg of Silexan, 20 of paroxetine, an antidepressant, and a placebo treatment. Results were measured every two weeks from baseline and monitored for significant differences.
Besides the paroxetine group, patients were not allowed to take psychiatric medication during the study or for 30 days prior. Despite initial intentions for the study to have two stages, the second stage was not carried out as the authors determined Silexan’s anxiolytic effects were significantly apparent during the first stage. The HAMA scale for anxiety was used during the bimonthly follow-ups to measure changes during treatment. HAMA score improvements were surprisingly significantly greater in either of the Silexan groups than in the SSRI or placebo groups.
Patients were considered to be responding to treatment if their HAMA scores decreased by 50% or more by the end of the treatment. Patients in remission were defined as a HAMA score less than 10. The Silexan treatments both showed the highest percentage of responding and remitting patients. The most common adverse effects during trials were infections, gastrointestinal disorders and nervous system disorders. There were five “serious adverse events” during the entirety of testing. The Silexan treatments and the placebo treatments had similar rates of adverse events, while the paroxetine group saw significantly higher rates. Amongst those in the Silexan group, the only significant divergence from the placebo rates was in the rates of gastrointestinal events, which were significantly more common than in the placebo, but still lower than in the paroxetine group. The authors concluded their study by asserting Silexan not only displayed significant anxiolytic properties but was safer than SSRIs in doing so. The study found that Silexan at either doses of 160 mg or 80 mg daily are at least as effective as paroxetine treatments, and in most cases are safer. This study’s results merit further investigation by independently funded research teams to determine more thoroughly just how efficacious lavender essential oils like Silexan are in combating general anxiety disorder.