When you take Medicine its for you to get better...But when you do Drugs its killing you...
Public perception.
"Drugs" and "Medicines" in the medical community are used interchangeably. There is even Medical Marijuana used for cancer patients for nausea, lack of appetite. What you are referring to is legal or illegal... That's determined by the Drug Enforcement Agencies etc. - what kind of drugs will most likely cause harm to yourself / others - impair judgement