Oral lavender oil (Silexan)

What lavender oil (Silexan) is

Silexan is an essential oil from the flowers of true lavender, Lavandula angustifolia, obtained by steam distillation and standardized to a fixed content; its main constituent is linalool. As Lasea, with 80 mg per soft capsule, it is an approved, pharmacy-only medicine in Germany. The EMA’s herbal committee (HMPC) also lists lavender oil as a traditional medicine for the relief of mild symptoms of stress and exhaustion and as a sleep aid.

What is rated here is the state of knowledge on oral Silexan. These trials do not apply to lavender as a scent, bath additive or massage oil. Related topics are valerian, ashwagandha, L-theanine and sleep & sleep hygiene.

How it works

The mechanism of action is not fully understood. According to the summary of product characteristics, an EEG study in healthy people shows that the active substance crosses the blood-brain barrier and triggers changes in the brain consistent with an anxiolytic effect. In a PET study in 17 healthy men, after at least eight weeks of 160 mg daily, binding at the serotonin 1A receptor was reduced in anxiety-relevant brain regions such as the hippocampus, insula and anterior cingulate gyrus; gray matter did not change.

Linalool peaks in the blood about one hour after intake, and the half-life is six to seven hours (summary of product characteristics). Unlike benzodiazepines, Silexan had no sedating effect in the trials.

What the studies show

Kasper 2010: subthreshold anxiety with sleep problems

In 27 general and psychiatric practices, 221 adults with an anxiety disorder not otherwise specified and disturbed sleep received 80 mg Silexan or placebo for ten weeks. The anxiety score on the Hamilton scale fell by 16.0 versus 9.5 points, the sleep index by 5.5 versus 3.8 points. 76.9 versus 49.1 percent responded to treatment, and 60.6 versus 42.6 percent reached remission. Silexan improved sleep quality and sleep duration without being sedating.

Kasper 2014: generalized anxiety disorder versus paroxetine

The largest single trial to date randomized 539 adults with generalized anxiety disorder in a double-blind design to 160 or 80 mg Silexan, 20 mg paroxetine or placebo for ten weeks. The Hamilton anxiety score fell by 14.1 and 12.8 points with Silexan, by 11.3 with paroxetine and by 9.5 with placebo. Both Silexan doses were significantly superior to placebo, paroxetine only as a trend (p = 0.10). A halving of anxiety scores was achieved by 60.3 percent with 160 mg, 51.9 percent with 80 mg, 43.2 percent with paroxetine and 37.8 percent with placebo. Side effects were less frequent with Silexan than with paroxetine. Two co-authors were employed by the manufacturer Dr. Willmar Schwabe.

Woelk 2010: versus lorazepam

In a double-blind trial in generalized anxiety disorder, the Hamilton anxiety score fell over six weeks by 11.3 points (45 percent) with Silexan and by 11.6 points (46 percent) with the benzodiazepine lorazepam, from 25 points each. The sleep diaries also showed comparable improvements in both groups.

Dold 2023: all placebo-controlled trials combined

The meta-analysis pools the five completed double-blind placebo-controlled trials in subthreshold anxiety, mixed anxiety-depression and generalized anxiety disorder, 1,213 participants with 80 mg over ten weeks. Silexan reduced anxiety in clinician and self-ratings and improved physical and mental quality of life. Side effects, serious side effects and dropouts did not differ from placebo. Here too, employees of the manufacturer are co-authors.

Where the data stop

• Independent confirmation. The large trials and the meta-analysis were produced with employees of the manufacturer as co-authors. That does not make the results wrong, but independent replications are rare.
• Sleep disorders as a diagnosis in their own right. In the trials evaluated here, sleep was measured only in people with anxiety. Whether Silexan helps with insomnia without anxiety has not been studied.
• More than three months. According to the summary of product characteristics, there are no clinical trials beyond three months; the approved treatment duration is limited accordingly.
• Other lavender oil. The results apply to Silexan. Other lavender oil capsules, scented oils or aromatherapy are not supported by them. The HMPC considered the patient numbers in the trials available up to 2012 too small to demonstrate an effect and therefore lists lavender oil only as a traditional medicine; the large trials came afterwards.

Status, approval and legal

Lasea (Silexan, 80 mg lavender oil per soft capsule) has been approved as a medicine in Germany since June 26, 2009, for the indication states of restlessness with anxious mood. It is pharmacy-only, not prescription-only. The approved dose is one soft capsule once daily for adults, and treatment should not exceed three months. It is not approved for children and adolescents under 18 years.

At EU level, the herbal committee HMPC lists lavender oil in its 2012 monograph as a traditional herbal medicine for the relief of mild symptoms of stress and exhaustion and as a sleep aid, for adults and children from 12 years.

Safety

According to the summary of product characteristics, the most common side effect is belching. Other gastrointestinal complaints and allergic skin reactions also occur; severe hypersensitivity reactions with swelling, circulatory or breathing problems have been reported and require immediate medical help.

Lasea must not be taken with impaired liver function; higher levels of the active substance were measured in liver cirrhosis. In severe kidney impairment, the amount of linalool in the blood almost doubles, which according to the summary of product characteristics is considered clinically not relevant. Lasea is not recommended during pregnancy and breastfeeding owing to lack of experience. Data for people over 65 years are limited.

If symptoms do not improve after one month or get worse, this should be checked by a doctor, according to the summary of product characteristics. Silexan has been studied in subthreshold anxiety, mixed anxiety-depression and generalized anxiety disorder, not in all forms of anxiety.

Sources

• Dold M et al., Eur Arch Psychiatry Clin Neurosci 2023 – Silexan in anxiety disorders, meta-analysis of 5 placebo-controlled trials
• Kasper S et al., Int J Neuropsychopharmacol 2014 – Silexan in generalized anxiety disorder versus placebo and paroxetine, 539 patients
• Kasper S et al., Int Clin Psychopharmacol 2010 – Silexan in subthreshold anxiety disorder, RCT with 221 patients
• Woelk H, Schläfke S, Phytomedicine 2010 – Silexan versus lorazepam in generalized anxiety disorder
• Müller TJ et al., Eur Arch Psychiatry Clin Neurosci 2026 – network meta-analysis of anxiety medications, 100 studies
• Baldinger P et al., Int J Neuropsychopharmacol 2014 – Silexan and the serotonin 1A receptor, PET study with 17 men
• Summary of product characteristics, Lasea 80 mg soft capsules (as of October 2021)
• EMA/HMPC – Lavandulae aetheroleum (lavender oil), EU monograph and summary