Lavender
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| Summary | |
|---|---|
| Binomial | Lavandula angustifolia |
| Family | Lamiaceae |
| Native range | Dry calcareous hillsides of the western Mediterranean: Provence (southern France), Spain, northern Italy, Croatia, and Greece; wild populations typically occur at 600 to 1,400 m elevation on exposed limestone garrigue and maquis. Widely cultivated throughout temperate Europe, North America, and Australia; Provence remains the global center of commercial cultivation. |
| Pharmacy | |
| Pharmacology | |
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 and traditional use
Western herbal medicine (primary centroid)
Lavender occupies the nervine class of Western herbal medicine -- herbs with an affinity for the nervous system -- and has been applied to the same cluster of indications across European herbal traditions for at least several hundred years: anxiety and nervous agitation, insomnia rooted in a restless mind, headache and migraine (particularly those with an anxiety or tension component), nervous indigestion and colic, neuralgia, and the diffuse condition the English herbalists called the "vapours" -- a category of nervous debility and emotional distress that has no exact modern diagnostic equivalent but maps substantially onto generalized anxiety disorder.
The traditional preparation for internal use was an infusion of dried flowers, drunk warm before sleep or during episodes of nervous distress. Lavender water -- a distillate of flowers in water or diluted alcohol -- was applied to the head and temples for headache. The tincture in 40-proof spirit was the apothecary preparation for internal use. The oil, expressed or steam-distilled from flowers, was rubbed onto the temples for headache, onto the chest for nervous respiratory complaints, and onto affected areas for neuralgia and joint pain. Lavender sachets placed in the bed or under the pillow were the traditional sleep aid; clothes stored with dried lavender sprigs were protected from moths. Every one of these forms is continuous in the Western herbal tradition from at least the 16th century.
Islamic medicine (Unani)
Lavender was known in Arabic-speaking medical traditions under the name Khuzami (Arabic: khuzama) and appears in the Unani materia medica as a cephalic (head-acting) herb, indicated for headache, epilepsy, and melancholy. Ibn Sina (Avicenna), writing in the early 11th century in the Canon of Medicine, recorded lavender for nervous headache and for strengthening the brain.[citation needed]
Aromatherapy tradition (20th century)
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.
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.
Essential oil: steam-distilled from fresh flowers; genuine L. angustifolia oil contains 25 to 45 percent linalool and 25 to 45 percent linalyl acetate, with camphor below 1 percent; these parameters distinguish true lavender from adulterated or substitute species. For topical use, always dilute in carrier oil (2 to 5 percent); neat application to intact skin carries some allergy risk even with true lavender oil, and dilution is the standard of practice.
Silexan (brand name Lasea; Schwabe Pharmaceuticals): a standardized pharmaceutical-grade oral lavender oil capsule formulated for gastrointestinal absorption; manufactured at pharmaceutical quality standards with defined linalool and linalyl acetate content. This preparation is not equivalent to and should not be substituted by tipping commercial essential oil into food or capsules: solubility, concentration, solvent matrix, and quality standards differ fundamentally. Silexan is a prescription medicinal product in Germany.
Tincture: 1:5 in 40 percent ethanol from dried flowers; the traditional apothecary form for internal use.
Hydrosol (lavender water): the aqueous condensate separated from essential oil during steam distillation; contains trace quantities of volatile oil in aqueous suspension; used topically in cosmetics and as a facial toner; not concentrated enough for pharmacological effects of the essential oil.
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.
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] 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.
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Titration and dosing
Internal preparations
Infusion (dried flower): 1 to 2 g dried flowers per cup of hot water, steeped 10 to 15 minutes; taken 2 to 3 times daily and at bedtime for sleep. Traditional dose with no robust clinical trial evidence for this form; the Commission E approval covers this preparation based on traditional use.
Tincture (1:5 in 40 percent ethanol): 0.5 to 1 teaspoon (2.5 to 5 ml) diluted in a small amount of water, taken 2 to 3 times daily. Traditional dose with no clinical trial evidence independent of the Silexan data.
Silexan oral capsule: 80 mg once daily, the dose used in all published RCTs; some protocols have used 160 mg/day for more severe anxiety without identified additional harm. Take with food. Clinical benefit in GAD trials was apparent by week two and fully established by week four to six.
External preparations
Essential oil topical: 5 to 10 drops (0.25 to 0.5 ml) diluted in 1 tablespoon (15 ml) carrier oil (yielding approximately 2 to 3 percent); applied by massage to affected area. Aromatherapy diffusion: 3 to 5 drops in 15 ml water in a cold-air diffuser in the bedroom at night. Traditional sleep preparation: 3 to 5 drops essential oil on a cotton ball placed on the pillow, or a dried lavender sachet under the pillow.
Recreational dose ladder
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.
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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,[1] 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.
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.
Patient 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 absence of dependence potential and withdrawal symptoms distinguishes Silexan from benzodiazepines. Patients anxious about benzodiazepine dependence or who have not tolerated them may find this distinction meaningful.
Patients using lavender essential oil products topically should use oils that are fresh, correctly stored (sealed, cool, and dark), and diluted in carrier oil for skin application; undiluted application to large skin areas over prolonged periods carries higher sensitization risk. Old or discolored essential oil should be discarded.
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.
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References
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