It is a common misconception that herbal remedies cannot be dangerous. This is false simply because some of the most dangerous medicines are derived from plant (e.g. digoxin, atropine). A website claims that a natural pain medication can be extracted from wild lettuce from your backyard. Interestingly the website bashes the addictive nature of pain pills at the same time it claims wild lettuce has opium like properties (1). Keep in mind that opium is an extremely addictive and dangerous substance; morphine and heroin are both opium derivatives and their danger is no secret.
A thorough literature review on wild lettuce revealed very few reliable studies. WebMD.com has a whole page on this herb using legitimate references: wild lettuce can be deadly if used in high doses. This is particularly dangerous if the herb is used for pain management; a patient in pain may increase the dose to a dangerous level if the analgesic effect is not strong enough.