synthetic drug related to morphine and used in medicine as a cough suppressant. The hydrobromide salt of dextromethorphan occurs as white crystals or a white crystalline powder, soluble in water, alcohol, and chloroform. It acts upon the central nervous system (nervous system, human) to suppress the cough reflex. The drug does not produce addiction or central depression, as do a number of other morphine derivatives, and it has no analgesic effect. For this reason it is commonly prepared in therapeutic doses in nonprescription cough syrups and tablets.

Dextromethorphan is also used as a recreational drug. When taken in large doses, the drug, referred to as DXM, can alter sensory perception and induce hallucination. Prolonged abuse has caused impairment of memory and other mental functions, and large doses taken in conjunction with antidepressants and other drugs have caused death by respiratory and cardiac distress.