Dextromethorphan is a chemical routinely used as an anti-tussive agent in numerous generic brand over-the-counter (OTC) cough suppressant medications. Its mechanism relies on its ability to centrally raise the threshold of the coughing reflex. In addition to its use in this capacity, it is known that dextromethorphan can be abused as a dissociative hallucinogen due to its antagonistic affects on the excitatory glutamate N-methyl-D-aspartate-receptor (NMDAR), which mimics the actions of narcotics such as ketamine and PCP, both of which antagonize the NMDAR. However, because of this pharmacological mode of action, Dextromethorphan may be effective as an analgesic agent. Care must be taken when using this medication, as it is contraindicated in individuals prescribed monoamine oxidase inhibitors and selective serotonin retuptake inhibitors as the combination may result in serotonin syndrome.