At recommended doses dextromethorphan, a common ingredient in most cough medicines like Sucrets®, Robitussin®, and NyQuil®, produces little or no central nervous system effect. At recreational doses, positive effects may include acute euphoria, elevated mood, dissociation of mind from body, creative dream-like experiences, and increased perceptual awareness. Other effects include disorientation, confusion, pupillary dilation, and altered time perception, visual and auditory hallucinations, and decreased sexual functioning.

Recreational doses impair judgment, memory, language, and other mental performances however the drug experience varies greatly depending on the amount of DXM ingested. Due to the high dosages needed for pleasurable effects, the potential for immediate and long term negative health consequences, and unpredictable nature at different dose levels, we strongly recommend that DXM be avoided.

Resources:
https://en.wikipedia.org/wiki/Dextromethorphan
https://www.erowid.org/chemicals/dxm/faq/dxm_experience.shtml
http://www.sethafitzgerald.com/