Lavender: Difference between revisions

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| intro        = ''Lavandula angustifolia'' Mill. -- true lavender, English lavender -- is a perennial aromatic shrub of the western Mediterranean garrigue, whose name descends from the Latin lavare, to wash, a record of the centuries it spent in the Roman bathhouse before it entered the clinic. Among aromatic herbs it holds a singular evidence record: a standardized oral preparation of its essential oil is the only essential-oil plant medicine to have been evaluated against a prescription anxiolytic in a randomized controlled trial and found non-inferior. Between the Roman bath and that trial stretches two thousand years of uninterrupted medicinal use for the same cluster of indications: anxiety, sleeplessness, and pain of the head.

| history      = The name came first. Pliny the Elder in the first century of the common era recorded the use of nardus gallicus -- a lavender relative -- as a bath additive throughout the Roman world, and later writers formalized the association with lavare.{{citation needed}}<!-- Candidate: Pliny the Elder. Naturalis Historia, Book 21 or 12 (plants). Standard scholarly edition: Rackham H, translator. Cambridge: Harvard University Press (Loeb Classical Library), 1938-1963. Topic: Roman use of lavender/nardus in bathing; nardus gallicus. No PMID; classical primary source. Verify book and chapter number at publish. --> The Greco-Roman medicinal plant was not ''L. angustifolia'' but its cousin ''Lavandula stoechas'' -- the French or Spanish lavender, high in camphor and pharmacologically distinct -- which Dioscorides in his De Materia Medica (1st century CE) recorded for headache, nausea, and disorders of the lung.{{citation needed}}<!-- Candidate: Dioscorides P. De Materia Medica. Standard English translation: Beck LY. Hildesheim: Olms-Weidmann, 2005. Topic: Dioscorides entry on stoechas (''Lavandula stoechas'') or relevant lavender species; indications for headache and respiratory use. No PMID; classical primary source. Verify book and chapter at publish. --> ''L. angustifolia'' entered European medicine through the medieval monastic garden, where Benedictine and Cistercian communities cultivated it as a strewing herb, a wash for wounds, and a remedy for the head -- the "vapours" of nervous complaint that would occupy it for centuries thereafter.

The German Commission E formally approved lavender flower for mood disturbances, restlessness, and insomnia in 1990, giving it a regulatory foundation in Germany at a time when most European herbal preparations lacked one. That approval rested on traditional use rather than clinical trial evidence; the trial evidence came later. Schwabe Pharmaceuticals developed Silexan -- a standardized pharmaceutical-grade oral lavender oil capsule -- in the 2000s and conducted a series of randomized controlled trials that collectively produced the most rigorous clinical evidence base of any aromatic herb medicine. The transition from bathhouse plant to evidence-based anxiolytic took roughly two thousand years and one burned hand.

| taxonomy    = ''Lavandula angustifolia'' Mill. (synonyms: ''L. officinalis'' Chaix, ''L. vera'' DC.) belongs to tribe Ocimeae, family Lamiaceae, one of approximately 40 species in the genus ''Lavandula''. The genus name derives from lavare (to wash); the species epithet angustifolia (narrow-leaved) distinguishes it from broader-leaved relatives. Four species and one hybrid group carry the majority of commercial and medicinal significance.

Wild ''L. angustifolia'' populations occur on exposed limestone hillsides in Provence, the Apennines, the Dalmatian coast, and the mountains of Spain and Greece. The English Pilgrims transported lavender to New England in 1620; it has naturalized in temperate climates worldwide without becoming invasive.{{citation needed}}<!-- Candidate: Chevallier A. Encyclopedia of Herbal Medicine. DK Publishing, 2000. Topic: lavender range, cultivation history, New England introduction. No PMID; secondary herbal reference. -->

| traditional_uses = '''Western herbal medicine (primary centroid)'''

Following Gattefosse's 1937 monograph, lavender essential oil became the foundational plant of the French aromatherapy tradition -- used topically and by inhalation for wound healing, burns, antisepsis, anxiety, and sleep. This tradition makes claims for lavender oil that overlap substantially with the traditional Western herbal tradition while adding an emphasis on topical wound-healing that traces directly to Gattefosse's burn. The distinction between aromatherapy (inhalational or topical use of essential oil) and the oral preparations studied in clinical trials is pharmacologically important and is addressed in the Clinical evidence section.

| pharmacology = '''Volatile oil constituents and mechanism'''

Topically, lavender essential oil has demonstrated broad-spectrum antibacterial and antifungal activity in vitro, including against methicillin-resistant ''Staphylococcus aureus'' (MRSA) and ''Candida albicans'', via disruption of microbial cell membrane integrity; wound-healing acceleration has been shown in animal models.{{citation needed}}<!-- Candidate: Cavanagh HM, Wilkinson JM. Phytother Res 2002; Sienkiewicz M et al., Molecules 2011 or similar. Topic: lavender oil antimicrobial activity in vitro; MRSA; Candida. Verify PMID at publish. -->

| clinical_evidence = The clinical evidence base for lavender divides sharply along route of administration. Oral Silexan (standardized lavender oil, 80 mg/day) has been evaluated in a series of double-blind randomized controlled trials; inhalation aromatherapy has been evaluated in a larger number of smaller trials with more modest and more variable effect sizes. The two evidence bodies should not be conflated.

The antimicrobial activity documented in vitro -- including activity against MRSA -- has not been translated into powered clinical trials. The topical wound-healing tradition has animal-model support but no placebo-controlled clinical trial data in humans.

| preparations = Dried flower (inflorescence): harvested before full bloom, dried at low temperature to preserve volatile oil; used for infusion, sachets, and as the starting material for tincture and essential oil production. Genuine lavender flower carries an immediately recognizable sweet-floral fragrance without camphor sharpness; camphoraceous character indicates ''L. latifolia'' or lavandin substitution.

Dried sachet: flowers loosely packed in muslin or linen, placed in drawers, linen closets, or under pillows; a traditional and household preparation continuous in use for sleep and moth-repellent purposes from at least the medieval period.

| dosing = '''Internal preparations'''

Lavender carries no established recreational dose structure in the ethnopharmacological or self-dosing literature. The anxiolytic and sedative ceiling at therapeutic doses is modest: Silexan at 80 mg/day produces an effect non-inferior to lorazepam 0.5 mg/day but does not produce sedation sufficient to impair cognition or function in the RCT population. Dose escalation beyond 160 mg/day oral (twice the standard dose) has not been systematically studied and produces no documented psychoactive intensification; the pharmacology -- GABA-A allosteric modulation and VGCC inhibition without direct GABA-A agonism -- predicts a dose-effect plateau rather than progressive deepening of central depression. No recreational culture of lavender use analogous to kava, valerian, or cannabis has been documented in any ethnobotanical or contemporary context. The essential oil used as an inhalant produces transient relaxation but no psychoactive profile warranting a tiered dose ladder.

| pharmacokinetics = Linalool and linalyl acetate in Silexan are absorbed from the gastrointestinal tract following oral administration; linalyl acetate undergoes hydrolysis to linalool in the gut and by plasma esterases, such that linalool is the principal circulating species. Peak plasma concentrations are reached approximately 30 to 90 minutes after oral dosing.{{citation needed}}<!-- Candidate: pharmacokinetics section from the Silexan clinical development literature; may be in a supplemental paper or in one of the Kasper publications. Search: "Silexan pharmacokinetics linalool" on eutils. Verify PMID at publish. --> Linalool undergoes hepatic metabolism via cytochrome P450-mediated hydroxylation and glucuronidation; the metabolites are excreted renally. No significant accumulation has been reported at 80 mg/day dosing.

Following inhalation, linalool is absorbed via the pulmonary mucosa and by olfactory epithelium; plasma concentrations are substantially lower than after oral administration of an equivalent linalool dose, consistent with the smaller effect sizes observed in aromatherapy relative to oral-Silexan trials.

| interactions    = Central nervous system depressants: theoretical additive sedation with benzodiazepines, alcohol, opioid analgesics, barbiturates, antihistamines, and sedating herbal medicines including valerian (''Valeriana officinalis''), kava (''Piper methysticum''), hops (''Humulus lupulus''), and passionflower (''Passiflora incarnata''). The clinical significance of this interaction at Silexan's standard 80 mg/day dose has not been formally evaluated; caution is appropriate when combining Silexan with benzodiazepines in patients transitioning from one agent to the other. The Woelk and Schlaefke (2010) trial documented successful lorazepam discontinuation in patients switched to Silexan,<ref name="woelk2010"/> suggesting that substitution is clinically feasible, but cross-tapering should be supervised.

Cytochrome P450: in vitro data at suprapharmacological concentrations suggest possible inhibition of CYP2C9 and CYP3A4 by lavender oil constituents. No pharmacokinetic interaction has been documented in clinical trials at 80 mg/day; the relevance of in vitro findings to standard clinical dosing is uncertain. No dose adjustment of co-administered medicines is presently supported by clinical evidence.

| interactionsummary = Additive CNS depression with sedatives, anxiolytics, alcohol, and sedating herbal medicines. No confirmed cytochrome P450 interaction at therapeutic dose.

| safety          = Silexan at 80 mg/day has been well tolerated in all published RCTs, with no serious adverse events attributed to the study medicine. The most commonly reported adverse effects have been mild gastrointestinal symptoms (nausea, belching with lavender odor) and headache, each occurring at low incidence and resolving without intervention.

Pregnancy: Silexan trials have excluded pregnant participants; safety data for oral lavender oil preparations in pregnancy are absent. Ordinary aromatherapy use (inhalation at ambient concentrations, topical application in diluted carrier oil) is generally considered low risk but is not supported by trial data. High-dose oral preparations should be avoided in pregnancy in the absence of safety information.

| monitoring      = No specific monitoring required for lavender flower infusion or tincture at traditional doses. Patients beginning Silexan 80 mg/day for generalized anxiety disorder: clinical assessment at two to four weeks to establish early response; continue through six weeks before assessing non-response. Patients with benzodiazepine dependence who are transitioning to Silexan should be supervised: cross-tapering under medical guidance is appropriate given the theoretical additive sedation risk during any overlap period.

| counseling      = Patients beginning Silexan should understand that it is derived from lavender essential oil but is not equivalent to lavender aromatherapy: the clinical evidence for anxiety comes specifically from the oral capsule formulation at 80 mg/day, not from diffusers, massage oils, or pillow sprays. Benefit may take two to four weeks to become fully apparent; onset latency resembles that of SSRIs more closely than the immediate sedation of benzodiazepines.

The prepubertal gynecomastia concern is worth mentioning to parents of boys who ask about lavender products; the evidence is from case reports rather than epidemiological studies, and the risk is not quantified, but the in vitro endocrine activity establishes a biologically plausible mechanism.

| regulatory      = '''Germany and European Union'''

MHRA traditional herbal registration: lavender preparations registered for traditional use for mild anxiety and sleep disturbance under the Traditional Herbal Registration scheme.

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[[Category:Plants]]