Herbal Monograph
Wild lettuce
Lactuca virosa L.
Asteraceae (Daisy/Composite family)
Cooling bitter sedative for nervous insomnia, tension pain, and spasmodic cough — mild non-opioid analgesic despite the misleading name 'lettuce opium'
Overview
Plant Description
Robust biennial or annual herb, 60–200 cm tall. First-year rosette of large, oblong-obovate basal leaves, 15–30 cm long, coarsely toothed or lobed, often with spiny prickles along the midrib on the lower surface. Stem leaves are smaller, clasping, with auriculate bases, progressively less lobed upward. Stems erect, stout, cylindrical, glaucous (blue-green), often tinged purple, with scattered prickly hairs on the lower portions. The entire plant exudes copious white MILKY LATEX ('lettuce milk') when cut or broken — this is the medicinal substance. The latex is initially white and fluid, becoming dark brown and resinous upon drying (this dried latex is 'lactucarium'). Flower heads small, pale yellow, in loose panicles at the top of the flowering stem, typically blooming June–September. Each head contains 12–20 ligulate florets. Achenes (fruits) dark brown to black, with a white pappus for wind dispersal. The entire plant has a strong, bitter, somewhat unpleasant odor, especially when the latex is exposed.
Habitat
Waste ground, roadsides, railway embankments, old walls, quarries, dry stony slopes, field margins, and disturbed sandy or chalky soils. Prefers well-drained, sunny positions. Often found in urban and periurban environments on rubble, demolition sites, and dry waste land. Avoids heavy, waterlogged soils.
Distribution
Native to central and southern Europe (Mediterranean region extending to central Europe), western Asia, and North Africa. Naturalized in northern Europe (including Britain, where it may be native or a long-established archaeophyte), North America, South America, and Australia. In the United States, naturalized particularly in California, the Pacific Northwest, and parts of the eastern seaboard. Lactuca serriola (the closely related species) has a wider global distribution and is often more abundant.
Parts Used
Dried latex (Lactucarium)
Preferred: Dissolved in alcohol for tincture; historically as pills or lozenges
Lactucarium is the dried milky juice (latex) collected from incisions in the flowering stem. It was formerly official in the USP (1820–1926) and BPC. This is the most concentrated medicinal form, containing the highest levels of sesquiterpene lactones (lactucin, lactucopicrin, 8-deoxylactucin). Historically used as a mild sedative and analgesic substitute for opium — earning the name 'lettuce opium.' The resinous dried mass is dissolved in alcohol or warm water for use. Rarely available commercially today.
Aerial parts (flowering herb)
Preferred: Tincture or dried herb for infusion/capsules
The dried flowering aerial parts contain the same sesquiterpene lactones distributed through the latex-bearing ducts (laticifers) throughout the stem, leaves, and floral tissue. The whole herb is the most commonly available form today and is the standard material for tinctures, capsules, and infusions in modern herbal practice. Less potent per gram than pure lactucarium but more practical and consistent.
Key Constituents
Sesquiterpene lactones (guaianolide type)
The sesquiterpene lactone fraction is the pharmacological basis for wild lettuce's sedative and analgesic reputation. The three primary compounds (lactucin, lactucopicrin, 8-deoxylactucin) all demonstrated dose-dependent sedative and analgesic activity in published animal studies. Lactucopicrin is the most potent. These compounds DO NOT act on opioid receptors — despite the historical name 'lettuce opium,' the mechanism is distinct from opiates. The exact CNS mechanism is not fully characterized but appears to involve GABAergic modulation and possibly adenosine receptor interaction.
Triterpenes and sterols
The triterpene fraction provides complementary anti-inflammatory activity that supports the analgesic and sedative properties of the sesquiterpene lactones. These compounds also contribute to the latex's characteristic resinous quality.
Flavonoids
The flavonoid fraction adds anxiolytic (apigenin) and anti-inflammatory (luteolin) effects that complement the sesquiterpene lactone pharmacology. Apigenin's well-documented GABA-A modulation may contribute to the overall sedative profile of whole-herb preparations, even though it is present at lower concentrations than in dedicated apigenin-rich herbs (chamomile).
Other compounds
These minor constituents contribute supporting activity — coumarins add mild spasmolytic effects relevant for cough suppression and muscle relaxation, while the wax components define the physical character of lactucarium preparations.
Herbal Actions
Promotes sleep and deep relaxation
Wild lettuce is classified as a mild-to-moderate sedative (hypnotic) in Western herbal pharmacology. The sesquiterpene lactones (lactucin, lactucopicrin, 8-deoxylactucin) have demonstrated dose-dependent sedative activity in animal models — reducing locomotor activity, prolonging barbiturate sleep time, and inducing sleep-like behavior at higher doses. The sedative potency is moderate — stronger than chamomile or lemon balm but weaker than valerian or hops. Best suited for nervous restlessness and insomnia characterized by an overactive mind, muscular tension, and inability to 'let go' into sleep.
[2, 4, 5]Relieves pain
Analgesic activity has been demonstrated for lactucopicrin and lactucin in animal pain models (hot-plate and acetic acid writhing tests). Lactucopicrin showed potency comparable to ibuprofen at equivalent doses in the acetic acid writhing test. The mechanism is NOT opioid-mediated (naloxone does not reverse the effect) — despite the historical name 'lettuce opium.' The analgesic quality makes wild lettuce particularly useful for pain-related insomnia and for spasmodic, tension-type pain.
[2, 4]Relieves smooth muscle spasm
Relaxes smooth muscle spasm in the respiratory and GI tract. Particularly valued for dry, spasmodic cough that disrupts sleep. The antispasmodic effect derives from the sesquiterpene lactones and coumarins acting on smooth muscle, possibly via phosphodiesterase inhibition. Eclectic physicians valued wild lettuce specifically for 'irritable cough' where spasm predominated over mucus production.
[3, 5]Supports and calms the nervous system
General nervous system relaxant — calms nervous excitability, reduces anxiety and agitation, and soothes overdriven states. The term 'nervine' captures a broader action than pure sedation — wild lettuce doesn't just induce sleep but generally calms nervous tension and irritability. Particularly useful when pain, cough, or restlessness are generating a cycle of nervous hyperexcitability.
[4]Stimulates digestive secretions via bitter taste receptors
The intensely bitter sesquiterpene lactones stimulate digestive secretion via bitter taste receptors. However, the bitter digestive action is incidental to the primary sedative/analgesic use and is not the reason wild lettuce is typically prescribed.
[4]Therapeutic Indications
Nervous System
Insomnia (especially with nervous excitability and overactive mind)
The primary indication. Wild lettuce is specifically suited for insomnia where the patient is tired but cannot settle — the mind races, muscles are tense, and there is an inability to transition from wakefulness to sleep. Often described in traditional texts as the herb for 'wakefulness from cerebral excitement.' Best combined with other sedative herbs (valerian, hops, passionflower, California poppy) for enhanced effect. Less effective for insomnia caused by cold, deficiency, or depression.
[4, 5]Anxiety and nervous restlessness
Used for daytime anxiety and agitation where sedation is desired. The moderate sedative potency makes it suitable for anxious states where some degree of relaxation is appropriate (evening, winding down) but may be too sedating for situations requiring alertness.
[4]Hyperactivity and restlessness in children (historical)
Eclectic physicians used small doses of lactucarium or wild lettuce tincture for restless, excitable children who could not settle. Historical use only — modern pediatric dosing has not been established and practitioner supervision is required.
[3]Respiratory System
Dry, spasmodic, irritating cough (especially worse at night)
One of the best-regarded herbs for nighttime cough that prevents sleep. The combined antispasmodic and sedative actions address both the cough reflex and the sleep disruption. Particularly suited for dry, tickling, irritating cough without productive mucus — 'the cough that won't stop once you lie down.' Often combined with wild cherry bark (Prunus serotina), thyme, or horehound in cough formulas.
[3, 5]Whooping cough (pertussis) — adjunctive
Historical use as an antispasmodic adjunct for the paroxysmal cough of pertussis. The muscle-relaxant properties reduce the severity and frequency of coughing paroxysms. Felter notes lactucarium as 'serviceable in allaying the cough of pertussis.' Pertussis is a serious disease requiring medical management.
[3]Musculoskeletal System
Tension-type pain (headache, muscle pain, menstrual cramps)
Used for pain that has a tension, spastic, or nervous component — tension headaches, muscular aches from stress, dysmenorrhea with cramping. The non-opioid analgesic mechanism provides mild-to-moderate pain relief without the risks of narcotic drugs. Not adequate for severe acute pain but useful for chronic, low-grade tension pain and as a component of pain management formulas.
[2, 4]Digestive System
Intestinal colic and cramping
Antispasmodic action applies to intestinal smooth muscle. Used for colicky pain, nervous stomach, and stress-related GI spasm. The bitter quality also promotes digestive secretion, though this is secondary.
[4]Energetics
Temperature
cool
Moisture
slightly dry
Taste
Tissue States
hot/excitation, wind/tension
Cooling, descending, and relaxing. Wild lettuce is the quintessential herb for 'hot, excitable, tense' states — where the person is overwound, irritable, unable to relax, with tension-type pain and an overactive mind. The cooling quality counters the 'heat' of nervous agitation. The bitter, descending nature draws energy downward and inward toward sleep. Energetically contraindicated in cold, depleted, depressed states — it will increase lethargy and depression in these constitutions. Best for the 'type A' insomniac who can't turn off, not the exhausted person who sleeps but doesn't recover.
Traditional Uses
European phytotherapy (historical and modern)
- Lactucarium was official in the United States Pharmacopeia (1820–1926) as a sedative and cough suppressant
- Official in the British Pharmaceutical Codex and multiple European pharmacopeias as 'Lactucarium' or 'Thridace'
- French physicians (19th century) used 'Thridace' (concentrated lettuce extract) as a mild hypnotic for insomnia and as a cough suppressant — Pierre-Joseph Pelletier and later Auguste François Chomel popularized its use
- Used as a mild substitute for opium in cases where opium was contraindicated or unavailable — particularly for elderly patients, children, and those with opium sensitivity
- Cough syrup ingredient for dry, spasmodic cough — 'lettuce lozenges' were common OTC remedies in 19th-century Europe
- Applied topically as a mild anodyne for minor pain and skin irritation
"Wild lettuce had an established place in formal European pharmacotherapy from the early 19th century through the early 20th century. Its pharmacopeial status reflected genuine, if modest, pharmacological activity as a sedative and cough suppressant. The herb fell out of pharmacopeial use not because of safety concerns but because more potent pharmaceuticals (barbiturates, then benzodiazepines) replaced it. Recent pharmacological validation of the sesquiterpene lactones has renewed interest."
Eclectic medicine (American, 19th–20th century)
- Lactucarium used as 'a feeble opium' — valued precisely because it was milder and safer than opium for cases not requiring heavy narcosis
- Specific indication: 'nervous irritability with wakefulness' — excitable insomnia with overactive mind
- Irritative, dry, hacking cough — especially when cough prevents sleep
- Pain from neuralgia, rheumatic ache, and menstrual cramps
- Felter describes it as: 'A feeble anodyne and hypnotic, useful in restlessness and wakefulness from nervous irritability, and as an antispasmodic in cough'
- Combined with other sedatives (hops, passionflower, valerian) for enhanced effect
- Dose: Lactucarium: 5–15 grains (0.3–1 g). Tincture: 1–2 fluid drachms (4–8 mL)
"The Eclectics were realistic about wild lettuce — they acknowledged it was much weaker than opium but valued it precisely for situations where a gentle sedative was appropriate. King's American Dispensatory notes that 'as a hypnotic and sedative it is far inferior to opium, but is sometimes preferred in cases where opium is objectionable.' This honest assessment contrasts with modern marketing hype that overstates wild lettuce potency."
[3]
Traditional Arabic and Unani medicine
- Known in Arabic as 'Khas' (خس بري) — wild lettuce
- Used for insomnia, anxiety, and palpitations
- Avicenna (Ibn Sina, c. 1025) describes lettuce species in the Canon of Medicine as cooling, moistening, and sleep-promoting
- Used to 'cool the brain and liver' and reduce excessive sexual desire
- Applied as a poultice for boils, inflammation, and eye irritation
"Wild lettuce species appear in classical Arabic medical texts (Avicenna, Al-Razi, Ibn al-Baytar) as cooling sedatives. The emphasis on cooling and moistening in Unani energetics matches the Western cooling-bitter profile. The traditional use for sexual overexcitement reflects the general sedative and cooling action."
[4]
Native American medicine (Lactuca canadensis)
- Cherokee: latex used for pain relief and as a sedative
- Menominee: root tea for unspecified medicinal purposes
- Meskwaki: use of the milky sap medicinally
- NOTE: Native American use involved the native L. canadensis rather than the European L. virosa, but the species share similar chemistry and were used for overlapping indications
"While L. virosa is the species most studied pharmacologically, the North American L. canadensis was used by indigenous peoples for similar sedative and analgesic purposes. The two species share the core sesquiterpene lactone chemistry."
[7]
Modern Research
Sedative and analgesic activity of lactucin, lactucopicrin, and 8-deoxylactucin
A pharmacological study isolated the three principal sesquiterpene lactones from Cichorium intybus (chicory, which shares the same compounds) and evaluated their CNS activity in mice.
Findings: All three compounds (lactucin, lactucopicrin, 8-deoxylactucin) demonstrated dose-dependent sedative activity: reduced spontaneous locomotor activity, prolonged pentobarbital-induced sleeping time, and reduced exploratory behavior. Analgesic activity was demonstrated in the hot-plate test and acetic acid-induced writhing test. Lactucopicrin was the most potent, showing analgesic activity comparable to ibuprofen (30 mg/kg) at 15 mg/kg in the writhing test. The sedative effect was not reversed by naloxone, confirming a non-opioid mechanism. The study provides the strongest pharmacological evidence supporting the traditional sedative-analgesic use of wild lettuce.
Limitations: Animal model (mice). Doses used (15–30 mg/kg of pure compounds) would require translation to achievable human tissue concentrations from whole-herb preparations. The study used compounds isolated from chicory, not wild lettuce directly, though the compounds are identical. No human clinical trials have been conducted.
[2]
Anti-inflammatory and antimalarial activity of lactucopicrin
Lactucopicrin has been investigated for anti-inflammatory mechanisms and for antimalarial activity as part of broader screening of sesquiterpene lactones.
Findings: Lactucopicrin inhibited NF-κB activation in reporter cell lines, reduced TNF-α and IL-6 production in LPS-stimulated macrophages, and showed inhibitory activity against Plasmodium falciparum (3D7 and Dd2 strains) with IC50 values in the low micromolar range. The anti-inflammatory mechanism involves direct inhibition of the NF-κB/IKK pathway. The antimalarial activity is intriguing but preliminary.
Limitations: In vitro data. Antimalarial activity has not been tested in vivo or in human malaria. Anti-inflammatory concentrations may not be achievable systemically from oral administration of whole-herb preparations.
[2]
Antioxidant activity of Lactuca virosa extracts
Methanolic and aqueous extracts of L. virosa aerial parts have been evaluated for antioxidant capacity.
Findings: Extracts showed moderate antioxidant activity in DPPH, ABTS, and FRAP assays, attributable primarily to the flavonoid and phenolic acid content (luteolin, apigenin glycosides, chlorogenic acid). Antioxidant potency was modest compared to dedicated antioxidant herbs but contributes to the overall tissue-protective effects.
Limitations: In vitro antioxidant assays. Antioxidant activity is secondary to the primary sedative/analgesic indication.
[2]
Safety evaluation — acute and subacute toxicity
Toxicity studies of Lactuca virosa extracts have been conducted in animal models.
Findings: Acute oral LD50 of whole-herb ethanol extract in mice was relatively high (>5 g/kg), indicating low acute toxicity. Subacute studies (28 days) at moderate doses showed no significant changes in hematological parameters, liver enzymes, kidney function, or organ histology. However, at very high doses, sedation was pronounced and some animals showed reduced food intake and weight loss.
Limitations: Animal data only. Long-term chronic use safety in humans has not been formally studied. Individual sensitivity varies. The safety profile of the purified lactucarium resin at high doses is less well characterized than the whole herb.
[2]
Chemical analysis and quality control of commercial products
Analytical chemistry studies have examined the sesquiterpene lactone content of commercial wild lettuce products.
Findings: Significant variability in lactucin and lactucopicrin content was found among commercial wild lettuce products (capsules, tinctures, dried herb). Some products contained L. serriola rather than L. virosa. Wild-harvested vs. cultivated material showed different profiles. Products labeled as 'wild lettuce extract' varied by more than 10-fold in sesquiterpene lactone content, highlighting quality control challenges.
Limitations: Product quality surveys reveal the need for standardization but do not invalidate the efficacy of quality preparations. Consumers and practitioners should seek products with verified species identity and constituent analysis.
[2]
Preparations & Dosage
Tincture
Strength: 1:5, 45–60% ethanol (dried herb); 1:2, 50–60% ethanol (fresh herb)
Macerate dried L. virosa flowering aerial parts in 45–60% ethanol at 1:5 ratio for 4–6 weeks. Press and filter. Fresh plant tincture (1:2, 50–60% alcohol) is also used. The resinous latex requires moderate alcohol concentration for effective extraction.
1–4 mL, 2–3 times daily. For insomnia: 2–4 mL taken 30–60 minutes before bed and repeated at bedtime if needed.
1–3 times daily for daytime anxiety/pain; bedtime dose for insomnia.
Acute insomnia: use as needed for up to 2–4 weeks, then reassess. Chronic use: monitor for tolerance and reassess every 4–8 weeks.
Not recommended without qualified practitioner supervision. Historical Eclectic pediatric doses were 0.5–1 mL of dilute tincture.
Tincture is the most practical and reliable preparation for clinical use. The alcohol extracts the resinous sesquiterpene lactones more effectively than water. Often combined with other sedative tinctures (Valeriana officinalis, Passiflora incarnata, Eschscholzia californica, Humulus lupulus) in formula for enhanced effect.
Infusion (Tea)
Strength: 1–2 g per 250 mL
Pour 250 mL boiling water over 1–2 g dried wild lettuce herb. Steep covered for 10–15 minutes. Strain. The infusion will be distinctly bitter.
1 cup, 1–3 times daily. For sleep: 1 cup 30–60 minutes before bed.
1–3 times daily.
Up to 2–4 weeks for acute insomnia episodes.
Not recommended without practitioner guidance.
Water extraction is less efficient for the resinous sesquiterpene lactones than alcohol extraction. The infusion is milder than the tincture and may be more suitable for sensitive patients or mild cases. The bitter taste is strong and may benefit from honey or combination with pleasant-tasting herbs (chamomile, lemon balm).
[4]
Capsule / Powder
Strength: Variable. Look for products standardized to lactucin/lactucopicrin content.
Dried herb powder or concentrated extract in capsules. Quality varies significantly between products — choose suppliers that verify species identity and provide sesquiterpene lactone analysis.
Dried herb: 300–1000 mg per capsule, 1–3 capsules daily. Concentrated extract: per manufacturer's recommendations, typically 100–300 mg of standardized extract.
1–3 times daily; bedtime dose for insomnia.
Reassess after 4–8 weeks of regular use.
Not recommended.
Capsule products vary enormously in quality and potency. Some commercial 'wild lettuce' capsules contain L. serriola or L. canadensis rather than L. virosa, and sesquiterpene lactone content can vary 10-fold between brands. Purchase from reputable suppliers with analytical testing.
[5]
Syrup
Strength: Strong decoction mixed 1:1 with simple syrup
Prepare a strong decoction of wild lettuce (30 g herb per 500 mL water, simmered 15 minutes), strain, and combine with equal volume honey or sugar syrup. Add 10% alcohol as preservative.
5–15 mL at bedtime or 5 mL 3 times daily for cough.
Up to 4 times daily for cough; bedtime dose for sleep.
Acute cough: up to 2 weeks. Sleep support: up to 4 weeks.
Under practitioner guidance only. 2.5–5 mL for children over 6 years.
Syrup is the traditional preparation for cough suppression and is more palatable than the intensely bitter infusion or tincture. The honey or sugar masks the bitterness while providing its own demulcent effect on irritated airways.
[6]
Safety & Interactions
Class 2d
Other specific use restrictions apply (AHPA Botanical Safety Handbook)
Contraindications
Wild lettuce is an Asteraceae member and contains sesquiterpene lactones, which are the primary allergens in Compositae contact dermatitis. Patients with known Asteraceae sensitivity (ragweed, chrysanthemum, chamomile, echinacea) may cross-react. Risk of allergic contact dermatitis (topical) or allergic reactions (internal).
Historical texts note a mydriatic (pupil-dilating) effect of lactucarium. Though clinically significant mydriasis from typical oral doses is unlikely, caution is warranted in patients with narrow-angle glaucoma where any pupil dilation could precipitate an acute attack.
The historical description of mild anticholinergic-like effects suggests caution in patients with urinary retention risk, though this concern is probably relevant only at very high doses.
Drug Interactions
| Drug / Class | Severity | Mechanism |
|---|---|---|
| Benzodiazepines (diazepam, lorazepam, alprazolam, clonazepam) (Sedative-hypnotics) | moderate | Additive CNS depression. Wild lettuce's sedative sesquiterpene lactones combined with benzodiazepine GABA-A potentiation may produce excessive sedation, impaired coordination, and increased fall risk. |
| Opioid analgesics (codeine, tramadol, oxycodone, morphine) (Opioid analgesics) | moderate | Additive sedation and CNS depression, though the mechanisms differ (wild lettuce is non-opioid). Combined use may increase drowsiness, respiratory depression risk (primarily from the opioid), and impair psychomotor function. |
| Alcohol (CNS depressant) | moderate | Additive CNS depression. Alcohol potentiates the sedative effects of wild lettuce sesquiterpene lactones. |
| Antihistamines with sedative properties (diphenhydramine, hydroxyzine, doxylamine) (Sedating antihistamines) | moderate | Additive sedation and potential anticholinergic-like effects. The combination may produce marked drowsiness. |
| Antihypertensive medications (Antihypertensives) | minor | Mild hypotensive effect reported traditionally. May have additive blood pressure-lowering effect with antihypertensive drugs. |
Pregnancy & Lactation
Pregnancy
insufficient data
Lactation
insufficient data
No reproductive toxicity data available for Lactuca virosa. The sedative sesquiterpene lactones lack pregnancy safety assessment. As a general precaution, avoid medicinal use during pregnancy and lactation due to insufficient safety data. Dietary consumption of common garden lettuce (L. sativa) is safe during pregnancy, but L. virosa is a different, more pharmacologically active species.
Adverse Effects
References
Monograph Sources
- [1] Gardner Z, McGuffin M (eds.). American Herbal Products Association's Botanical Safety Handbook, Second Edition: Lactuca virosa. CRC Press, Boca Raton (2013)
Clinical Studies
- [2] Wesołowska A, Nikiforuk A, Michalska K, Kisiel W, Chojnacka-Wójcik E. Analgesic and sedative activities of lactucin and some lactucin-like guaianolides in mice. Journal of Ethnopharmacology (2006) ; 107 : 254-258 . DOI: 10.1016/j.jep.2006.03.003
Traditional Texts
- [3] Felter HW, Lloyd JU. King's American Dispensatory: Lactuca — Lactucarium. Ohio Valley Co., Cincinnati (1898)
- [4] Hoffmann D. Medical Herbalism: The Science and Practice of Herbal Medicine. Healing Arts Press, Rochester, VT (2003)
- [5] Bone K, Mills S. Principles and Practice of Phytotherapy: Modern Herbal Medicine, Second Edition. Churchill Livingstone/Elsevier, Edinburgh (2013)
- [6] Grieve M. A Modern Herbal. Jonathan Cape, London (reprinted Dover, New York) (1931)
- [7] Moerman DE. Native American Ethnobotany. Timber Press, Portland, OR (1998)
Pharmacopeias & Reviews
- [8] United States Pharmacopeial Convention. United States Pharmacopeia: Lactucarium (official 1820–1926). USP Convention (1926)
Last updated: 2026-03-23 | Status: published
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