Bitter lettuce
StarLactuca virosa
Synonyms: Wiestia virosa, Lactuca scariola subsp. virosa
Western Herbalism Properties
Traditional Uses
The Navajo used Lactuca virosa as an antidiarrheal and antiemetic for gastroenteritis and other gastrointestinal complaints (Hocking, 1956). In European and Eclectic herbal practice the dried milky latex, known as lactucarium or 'lettuce opium', was valued as a mild sedative and to ease coughs and restlessness (Grieve; King's American Dispensatory).
Gallery
Botanical Description
Lactuca virosa, the wild lettuce or bitter lettuce, is a robust biennial herb in the aster family (Asteraceae) growing 60 to 200 cm tall. The erect, often reddish-tinged stem exudes a bitter white latex when cut and bears stiff prickles along the lower midribs. The leaves are large, oblong to obovate, clasping the stem, with spiny-toothed margins and a prickly underside midrib, the lower ones sometimes lobed. Numerous small pale-yellow flower heads, each composed entirely of ray florets, are arranged in a broad branching panicle and bloom in mid to late summer. The fruits are flattened, dark achenes bearing a white pappus for wind dispersal. Native to Europe, North Africa, and western Asia, it is naturalized elsewhere and grows on waste ground, roadsides, banks, and disturbed sunny sites.
Active Constituents
Lactucin
Guaianolide sesquiterpene lactoneConcentration: Principal bitter lactone of the dried latex (lactucarium)
An intensely bitter guaianolide with documented analgesic and sedative activity in animal models; a chief basis for the plant's traditional use for pain and restlessness. In the mouse hot-plate test it produced analgesia comparable to ibuprofen.
Lactucopicrin
Guaianolide sesquiterpene lactone (p-hydroxyphenylacetate ester of lactucin)Concentration: Major bitter lactone of the latex
Reported to be the most potent analgesic of the wild-lettuce lactones, with additional sedative (reduced locomotor activity) effects in mice; contributes strongly to the bitter, opium-like folk reputation of lactucarium.
11beta,13-Dihydrolactucin
Guaianolide sesquiterpene lactoneConcentration: Minor bitter lactone
Shows analgesic activity in mice but, unlike lactucin and lactucopicrin, lacked clear sedative effects, indicating the analgesic and sedative actions are partly separable across these related lactones.
Lactucin-8-O-methylacrylate / lactucopicrin-15-oxalate and related esters
Guaianolide sesquiterpene lactone estersConcentration: Minor constituents of the latex
Naturally occurring ester derivatives of the core guaianolides that add to the total bitter, biologically active lactone fraction.
Flavonoids (quercetin and luteolin glycosides)
Flavonoid glycosidesConcentration: Present in leaf tissue
Contribute antioxidant activity typical of Asteraceae leaves, though they are not the source of the sedative reputation.
Triterpenes (taraxasterol, lactucerol/alpha-lactucerol)
Triterpenoid alcoholsConcentration: Constituents of the milky latex
Non-bitter lipophilic components of the latex that make up part of the solidified 'lettuce opium' but have no established sedative action.
Coumarins (aesculin, cichoriin)
Hydroxycoumarin glycosidesConcentration: Minor constituents
Common Lactuca coumarins that add to the overall phytochemical profile; not primary bioactives of the sedative fraction.
⚠ Drug Interactions
CNS depressants (benzodiazepines, barbiturates, opioids, sedating antihistamines, alcohol)
Wild-lettuce guaianolides (lactucin, lactucopicrin) depress the central nervous system and reduce locomotor activity in animals, so combining wild-lettuce preparations with other sedatives could add to drowsiness and impaired alertness.
Clinical note: Caution with driving/machinery; avoid stacking with other sedatives or alcohol. Human interaction data are lacking, so the concern is precautionary.
Preparation Methods
Dried leaf infusion
Parts: Leaves, Flowering tops
The dried aerial parts are infused as a bitter tea taken in the evening for its traditional mild sedative/relaxant effect. Start with small amounts; the very bitter taste is characteristic.
Lactucarium (dried latex)
Parts: Milky latex from cut stems/flowering heads
The white latex is air-dried into brown 'lettuce opium', historically used in small doses as a sedative and cough remedy. Potency of latex and its lactone content varies widely between plants and seasons, so dosing is imprecise.
Tincture / hydroalcoholic extract
Parts: Leaves and flowering tops
A hydroalcoholic tincture is used in drop doses as a sedative and antitussive. Excessive doses of wild lettuce can cause nausea, sweating, dilated pupils (mydriasis), dizziness and, historically, more serious toxicity, so it should be used in modest amounts and avoided in pregnancy.
Clinical Studies
Analgesic and sedative activities of lactucin and some lactucin-like guaianolides in mice
Lactucin, lactucopicrin and 11beta,13-dihydrolactucin (characteristic bitter guaianolides of Lactuca virosa) were tested in mice. At 15 and 30 mg/kg they produced analgesia in the hot-plate test comparable to ibuprofen 30 mg/kg, and in the tail-flick test the 30 mg/kg dose matched ibuprofen 60 mg/kg, with lactucopicrin the most potent. Lactucin and lactucopicrin (but not the dihydro derivative) also reduced spontaneous locomotor activity, confirming sedative activity. No human clinical trials establish these effects in people.
Historical Texts
Dioscorides, De Materia Medica
1st century CE (Greco-Roman)United States Pharmacopoeia / 19th-century Eclectic and European pharmacopoeias
19th centuryNicholas Culpeper, Complete Herbal
1653 (17th-century England)References
- 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) [DOI]
- Wichtl M (ed.). Herbal Drugs and Phytopharmaceuticals (monograph: Lactucae virosae herba / Lactucarium) . Medpharm Scientific Publishers / CRC Press (2004) [DOI]
This information is for educational purposes only and is not intended to replace professional medical advice. Always consult a qualified healthcare provider before using any herbal remedy, especially if you are pregnant, nursing, or taking medications.
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