Before the Harrison narcotic act in 1914 there was never such a thing as an "illegal drug" there were laws about adultering products with poison but the concept of illegal drugs or a "war on drugs" didn't exist before 1914 in the US.

I am not sure how addicts were treated by law enforcement historically but would be curious to hear about that. Just my own intuition says they probably were treated under existing vagrancy laws "Vagrancy laws took myriad forms, generally making it a crime to be poor, idle, dissolute, immoral, drunk, lewd, or suspicious."