Dextromethorphan

Dextromethorphan (DXM or DM) is an antitussive (cough suppressant) drug. It is one of the active ingredients in many over-the-counter cold and cough medicines, such as Mucinex DM, Robitussin, NyQuil, Dimetapp, Vicks, Coricidin, Delsym, TheraFlu, and others, including generic labels. Dextromethorphan has also found other uses in medicine, ranging from pain relief to psychological applications. It is sold in syrup, tablet, spray, and lozenge forms. In its pure form, dextromethorphan occurs as a white powder.

DXM is also used recreationally. When exceeding label-specified maximum dosages, dextromethorphan acts as a dissociative hallucinogen. Its mechanism of action is via multiple effects, including actions as a nonselective serotonin reuptake inhibitor and a sigma-1 receptor agonist and the action of its major metabolite dextrorphan as an NMDA receptor antagonist, producing effects similar yet distinguished from the dissociative substances ketamine and phencyclidine on the higher spectrum of doses or "plateaus", as well as the active metabolite 3-methoxymorphinan, which produces local anesthetic effects in rats with a potency above dextrorphan but below dextromethorphan itself.