Other forms: emetics
An emetic is a medicine or potion that makes you vomit, which you might be given if you've taken poison or some other harmful substance.
You can also use the word emetic in a more figurative sense to describe anything that makes you feel sick — the motion of a boat rocked by a storm could easily be an emetic, and the tuna sandwich the guy sitting next to you on the bus has just unwrapped might also be an emetic for everyone sitting nearby.