Scientific Name(s): Lactuca sativa var capitata L. (garden lettuce)., Lactuca virosa L. (wild lettuce).
Common Name(s): Acrid lettuce, Garden lettuce, German lactucarium, Greater prickly lettuce, Green endive, Lettuce opium, Strong-scented lettuce, Wild lettuce
Widely cultivated, lettuce flowers from July to September. This biennial herb grows to 1.8 m. The large leaves can attain lengths of 0.46 m. The stalks are rich in a milky-white sap that flows freely when the stems are broken.1
Lettuce opium has been used in folk medicine for indications ranging from aiding circulation to treating swollen genitals. In Europe, it is used as a substitute for opium in cough mixtures.2 In homeopathy, a tincture has been used for laryngitis, bronchitis, asthma, cough, and urinary tract infections.3 The juice of the stem covering yields a medicinal extract known as thridace, the use and efficacy of which is widely disputed.4
In Chinese medicine, lettuce preparations have been widely used. The dried juice has been recommended as a topical wound antiseptic, and the seeds have been used as a galactogogue (to increase the flow of milk in nursing mothers). It has been claimed that the flowers and seeds are effective in reducing fevers.5 Lettuce opium products have been marketed as legal highs or narcotic substitutes intended to be smoked alone or in combination with marijuana to enhance potency and flavor.6 Its analgesic and sedative attributes seem more based on fiction than fact.
Some confusion exists regarding the nomenclature of the products derived from L. virosa and related plants. Flowering lettuce plants contain large amounts of a milky-white sap, which has a bitter taste and strong opiate-like odor. When the juice is collected and is exposed to air, it turns a brownish color. This substance is called lactucarium, a mixture of compounds to which the touted narcotic properties of the product have been ascribed. Lactucarium has been reported to contain approximately 0.2% lactucin, a sesquiterpinoid lactone. Additionally, the mixture contains a volatile oil, caoutchouc, mannitol, and lactucerol (taraxasterol) (approximately 50%). Lactucerin, also found in the latex, is the acetyl derivative of taraxasterol, a widely distributed triterpene.5, 7
Uses and Pharmacology
A variety of legal, alternate "hallucinogenic" products containing lettuce opium have been available on the market. Brand names of such products include Lettucine, Black Gold, Lettucene, Lettuce Hash, and Lopium. These products contain a lettuce derivative or lactucarium and are smoked in pipes or heated in small bowls, and the vapors are inhaled. These extracts are sometimes combined with damiana distillates, African yohimbe bark, or catnip distillates.
Research reveals no animal data regarding the use of lettuce opium for hallucinogenic effects.
The hallucinogenic effect is usually mild and appears to be related to the degree of user expectation. There is no pharmacologic basis for the purported hallucinogenic effects of lettuce opium.
Lettuce leaf cigarettes have been marketed as nicotine-free tobacco substitutes. Support for such alternatives has been variable because of slow acceptance of the unique flavor and the lack of a nicotine-induced kick.
Phytochemical and biological screening of several Lactuca species indicates that the genus has no antimicrobial activity, slight antitumor activity, and can produce gross CNS effects in mice.10, 11 However, the Lactuca species has resistance to viruses, bacteria, and fungi (Bremia lactucae).12
While lactucin and lactucopicrin have been reported to have depressant and sedative activity on the CNS, these compounds are chemically unstable; commercial lactucarium contains little, if any, of these.13 Latex of L. sativa has been shown to inhibit the growth of Candida albicans in vitro.14 Extracts of L. sativa resulted in hypotension when administered to dogs.6
There is no recent clinical evidence to support specific dose recommendations.
Pregnancy / Lactation
Information regarding safety and efficacy in pregnancy and lactation is lacking.
None well documented.
Case reports are lacking; however, a possible association exists between lettuce ingestion and a localized oral allergic reaction.15
Reports of mydriasis, dizziness, anxiety, urinary retention, decreased bowel sounds, and sympathetic over-activity have been published. An anticholinergic mechanism is suggested.16 Mortality in dogs has been reported following intravenous administration.16, 17
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