Narcotic a. : Having the properties of a narcotic; operating as a narcotic.

Narcotic n. : A drug which, in medicinal doses, generally allays morbid susceptibility, relieves pain, and produces sleep; but which, in poisonous doses, produces stupor, coma, or convulsions, and, when given in sufficient quantity, causes death. The best examples are opium (with morphine), belladonna (with atropine), and conium.

Example:
Do you know if being on Narcotic medication will result in a irregular menstrual period?

Taxonomy
narcotic, drug, dose, dependence, opioid, tolerance, drug use, narcotic drug, street drugs, withdrawal symptoms, free encyclopedia, heroin, agents, substances, pain, dependency, injectors, duration.

Defination from the web:
narcotic (ναρκωτικός) is believed to have been coined by the Greek physician Galen to refer to agents that benumb or deaden, causing loss of feeling or paralysis. ... how patients understand the terms 'opioid' and 'narcotic'." Journal of General Internal Medicine. ...