Lactuca virosa is ingested often for its mild psychotropic (specifically hypnotic or sedative) effects which are often described as being similar to that of opium.
L. virosa was used in the 19th century by physicians when opium could not be obtained. It was studied extensively by the Council of the Pharmaceutical Society of Great Britain in 1911. They discovered two chemicals responsible for the properties of L. virosa; lactucopicrin and lactucin.
In the United States, the plant experienced a resurgence in popularity in the 1970s. Today the plant is un-scheduled by the Food and Drug Administration (FDA), meaning it is legal to grow, purchase and own without prescription or license.
The effects of ingesting L. virosa are similar to opium, although no opiates are present in the plant. A latex however exists as an extract of the stem secretion of Lactuca virosa, a simple preparation in a manner resembling opium, which is called lactucarium. One of the active compounds, lactucin, is an adenosine receptor agonist, while another, lactucopicrin, has been shown to act as an acetylcholinesterase inhibitor. Effects are felt quickly but do not last long, between half an hour to a couple of hours. They dwindle slowly.
The plant has been used as an anesthetic and a sleep aid, as well as recreationally. Oils and extracts can also be produced from L. virosa. These oils and extracts are often added to tea to help induce sleep. Many add the greens to salads, though the leaves of L. virosa are more bitter than other salad greens.
Smoking involves either dried leaves or a sticky precipitate extracted from the leaves. Beverages can be prepared by soaking the leaves in alcohol. The plant contains flavonoids, which have strong anti-oxidant properties. L. virosa has also been found to contain coumarins, and N-methyl-β-phenethylamine.