Wild lettuce, scientifically known as Lactuca virosa, is a biennial plant belonging to the daisy family, Asteraceae, which also includes common lettuce and dandelion [citel: 1, 7]. The plant is characterized by its tall, erect structure, often reaching heights of six feet, and its growth cycle spans two years [citel: 6, 11]. Its common name comes from the thick, milky sap, called lactucarium, that flows when the stem or leaves are damaged [citel: 1, 6]. This latex-like secretion is the substance historically associated with the plant’s distinctive properties [citel: 6, 10].
Identifying Wild Lettuce
Lactuca virosa is a stout, herbaceous plant [citel: 1, 11]. The stem is usually light green, sometimes spotted with purple, and features small, stiff hairs or prickles, particularly near the base [citel: 1, 6]. Its leaves are deeply lobed or pinnatifid, up to a foot long, and possess tiny spines along their margins [citel: 1].
The plant produces small, pale yellow flowers grouped in a panicle-like arrangement near the top of the stem [citel: 1]. After flowering, it forms seeds attached to white, feathery plumes, similar to a dandelion, which aid in wind dispersal [citel: 1, 16]. Wild lettuce is native to Europe, North Africa, and West Asia, but it has been widely introduced and naturalized across North America [citel: 1, 11]. It thrives in disturbed habitats, frequently appearing along roadsides, in waste areas, and fields [citel: 3].
Historical Use in Traditional Applications
The milky sap, lactucarium, was the primary focus of the plant’s traditional use, particularly in the 19th century [citel: 2, 5]. This dried sap was historically valued for its mild sedative and pain-relieving effects [citel: 2, 4]. Apothecaries and herbalists prepared lactucarium into syrups, lozenges, and tinctures for various ailments [citel: 2, 10].
Wild lettuce gained popularity in the United States and Europe as a non-addictive alternative to restricted substances [citel: 2, 10]. Its reputation led to the nickname “poor man’s opium” or “lettuce opium,” reflecting its perceived ability to offer a milder, non-narcotic form of relief [citel: 2, 6]. Pharmacopeias in the late 19th and early 20th centuries even listed lactucarium for use as a mild hypnotic for insomnia and a sedative for irritable coughs [citel: 5, 10].
Understanding the Active Compounds
The plant’s effects are primarily attributed to sesquiterpene lactones found in the lactucarium [citel: 6, 13]. The two main bitter compounds are lactucin and its derivative, lactucopicrin [citel: 6, 7]. These compounds are believed to act on the central nervous system, producing analgesic and mild sedative properties [citel: 4, 15].
Research, often conducted in animal models, suggests that a combination of lactucin and lactucopicrin can have pain-relieving effects comparable to a standard dose of ibuprofen [citel: 6, 7]. Studies in mice show that lactucopicrin is the more potent analgesic, possibly acting as an acetylcholinesterase inhibitor [citel: 7, 12]. These compounds have also been investigated for potential anti-inflammatory activity [citel: 6, 12]. Despite promising preclinical data, robust clinical trials in humans remain limited, meaning the scientific evidence supporting these effects in people is preliminary [citel: 2, 7].
Modern Safety Concerns and Regulation
Wild lettuce, while possibly safe in small, controlled amounts, carries significant risks, particularly with non-standardized consumption [citel: 14]. Overdosing or consuming large amounts can lead to adverse effects, including dizziness, pupil dilation, sweating, and restlessness [citel: 5, 14]. The plant’s milky sap can also cause contact dermatitis or skin irritation in individuals with a latex allergy [citel: 3, 7].
A concern is the risk of misidentification, as wild lettuce can be confused with genuinely toxic plants, potentially leading to severe poisoning [citel: 16]. As a dietary supplement, wild lettuce is not tightly regulated, meaning there is no standardized dosing or guarantee of product purity and concentration [citel: 7, 14]. Its long-term safety is unknown, and its use is contraindicated for pregnant or breastfeeding individuals [citel: 7, 14]. It should also be avoided before surgery due to potential interactions with anesthesia [citel: 7, 14].