Herb library · Herb · Lactuca virosa
Wild lettuce
A bitter relative of garden lettuce whose dried milky sap, lactucarium, was sold in the 1800s as "lettuce opium" for sleep and pain. It now turns up among natural psychoactive products, but no clinical trials exist, and eating the plant has put people in the hospital.
Serious warning
A 2009 case series reports eight people hospitalized with poisoning after eating wild lettuce, one needing intensive care. There are no studies showing a safe dose.
Traditional use
A European plant whose stem gives a bitter white latex when cut. Dried into cakes, this lactucarium was listed in the U.S. and British pharmacopoeias and used as a milder substitute for opium for sleeplessness and cough, though 19th-century doctors disagreed about what it actually did. The North American plant often called wild lettuce (Lactuca canadensis) is a different species.
What studies show
- Insufficient
Sleep, anxiety and pain: there are no clinical trials. What is known in people comes from reports of poisoning, and a 2020 review lists it among plant-based psychoactive products whose active compounds have hardly been studied in the body.
Be careful of
Cautions
- NoteEating the plant has caused poisoning: a 2009 report describes eight people in northern Iran who needed hospital care after eating wild lettuce, one of them in intensive care. All recovered.
- NoteA 2020 review lists it among natural "new psychoactive substances", and its abuse has been reported in France.
- InteractionIt is taken for a sedative effect. Ask a pharmacist before combining it with sleep medicines, sedatives or alcohol.
- Ask a clinicianTalk with a clinician or pharmacist before using this if you take prescription medicines, are pregnant or breastfeeding, or are giving it to a child.
From the old books
What herbals and dispensaries of the past printed. History, in their words.
“Lactucarium has never been thoroughly and satisfactorily investigated in relation to its therapeutical influences; indeed, various experimenters differ in their views on this point, some asserting it to be a stimulant and others a sedative.”
Sources
- Wild lettuce (Lactuca virosa) toxicity (BMJ Case Rep, 2009) (opens in a new tab) · NIH · read September 25, 2026
- Abuse of lactuca virosa (Presse Med, 2003) (opens in a new tab) · NIH · read September 25, 2026
- Biomedical analysis of New Psychoactive Substances (NPS) of natural origin (J Pharm Biomed Anal, 2020) (opens in a new tab) · NIH · read September 25, 2026
- Lactuca virosa, the poison lettuce (Pharmazie, 1948) (opens in a new tab) · NIH · read September 25, 2026
Reviewed September 25, 2026.