Emetics are herbs that will induce vomiting. Used much more historically, their use is rarely indicated in medicine today. Their main use is in the first aid treatment of poisoning where they will empty the content of the stomach.
How Emetics Work
Most work through irritation of the either the stomach or the nervous system. Some Expectorants are emetics in high doses, and there is some relationship between the mechanism by which both work.
Herbal Examples:
Lobelia (Lobelia inflata)
Ipecac (Cephaelisipecacuahana)