Wild lettuce (Lactuca virosa): Uses, Evidence and Safety

Safety first: wild lettuce is not a harmless salad plant

The best human report we found is a case series of eight people, aged 12 to 38, who were treated in a hospital in Iran after eating wild lettuce. [1] Their problems included loss of consciousness, agitation, hallucinations, dilated pupils, dry mouth, blurred vision, urinary retention, severe sweating, vomiting and abdominal cramps. [1] All eight recovered, one after 48 hours in intensive care, and no long-term problems were reported. [1] The authors noted that opinions on its medical value are divided and that some people class it as a poison. [1] A consumer health article adds that experts advise against eating it like ordinary lettuce, that foraging it is unsafe unless a person is qualified, and that it may not suit pregnant people. [3] No source we read gave a safe amount. Please do not use it in place of treatment for pain or sleep problems, and see a doctor if you have taken it and feel unwell. See how herb and medicine interactions work, supplements before surgery and foraging and wildcrafting safely.

Overview

Wild lettuce here means Lactuca virosa L., a plant in the daisy family (Asteraceae). GBIF lists Lactuca virosa as an accepted species name. [4] It is a tall biennial that grows on riverbanks and waste ground, and the whole plant contains a bitter milky juice. [1] When the juice dries and hardens it is called lactucarium, nicknamed "lettuce opium". [1] The "opium" name is only a nickname: the sources we read describe its historical effects as milder than opium, and the plant is not an opium poppy. [3] This page covers L. virosa, its latex and products made from it. It does not cover garden lettuce (Lactuca sativa), and other "wild lettuce" plants in the same genus are a different matter: they can differ in what they contain. [2] Which exact species is in a product can be hard to check, so read botanical names and plant parts on labels.

Traditional use (not proof of benefit)

The case-report authors list historical uses as a sedative, pain reliever, diuretic, laxative and anticonvulsant, and also for kidney problems, uterine pain, swelling, insomnia, menstrual pain, cough, whooping cough and asthma. [1] Skin use for sunburn and enemas for gut irritation are also mentioned. [1] The same paper says it offers no controlled clinical data for these effects. [1] Long use is not proof that something works or is safe.

What research shows

We found no human trial of Lactuca virosa in the sources we read. The first page of PubMed results for the Latin name showed one case report, several plant-genetics papers, and no clinical trial. [5]

The mouse study also showed a reason for caution: different Lactuca latexes behaved differently, and the authors saw effects that did not simply track one compound. [2] That means one plant, product or batch cannot be assumed to act like another.

Forms and why the form matters

Products are sold as tablets, liquid tinctures, powdered extracts, resin and dried herb. [3] The same article says the plant latex can irritate the skin when fresh. [3] The compounds named in the case report (such as lactucin and lactucopicrin) and traces of hyoscyamine, a medicine-like substance that can cause the dry mouth and dilated pupils seen in the patients, are not controlled in a typical shop product. [1] Strength, species and purity can therefore vary. How much to use is a decision for a clinician, and we give no amounts.

Safety in more detail

• Side effects reported in poisoning: drowsiness or loss of consciousness, agitation, anxiety, dizziness, unsteady walking, headache, hallucinations, euphoria, dry mouth, dilated pupils, blurred vision, urinary retention, sweating, flushing, nausea, vomiting and cramps. [1]
• Cause of the toxic effects: the authors suggest traces of hyoscyamine are probably behind the sedative effect. [1] This was their opinion, not a measured finding in those patients.
• Medicines: a consumer article says wild lettuce may interact with medicines but names none. [3] Because it can cause drowsiness and anticholinergic-type effects, ask a pharmacist before combining it with sedatives, sleep aids, alcohol or other herbs. This is a general precaution, not a documented interaction from the sources we read. See herbs for sleep: what research shows.
• Pregnancy: one article says it may be unsuitable, with no detail. [3] Proper evidence of safety was not found in the sources we read, so we do not suggest using it. See pregnancy and breastfeeding safety.
• Breastfeeding and children: Proper evidence not found in the sources we read. The youngest patient in the case series was 12. [1]
• Liver and kidney: Proper evidence not found in the sources we read. We could not open NIH's LiverTox site, so we make no claim either way.
• Surgery: Proper evidence not found in the sources we read. Because it may cause drowsiness, tell the surgical team about any product. See supplements before surgery.
• Skin: fresh latex may irritate skin. [3]
• Quality and contamination: the sources we read do not test commercial products. Plants in this genus resemble each other, so mix-ups are possible; see adulteration, substitution and mislabeling.

Official statements

We could not find a monograph or fact sheet on Lactuca virosa from NCCIH, Memorial Sloan Kettering or the European Medicines Agency (the pages we tried were not found or were blocked), so we cannot report an official position. Proper evidence not found in the sources we read.

Related pages

• Valerian
• Passionflower
• Hops
• Herbs for sleep: what research shows
• Herbs for anxiety and stress: what research shows
• Foraging, wildcrafting and growing herbs safely