19th century people used narcotics, how could they survive?

This question may be stupid for you. It’s just something that pop into my mind a few seconds ago

Books and movies about 19th century (especially those about Victorian time) tend to portray people using narcotics (heroine, cocaine and the like). There are fictional characters using narcotics as a daily basic (Sherlock Holmes, inspector Frederick Abberline from the movie From Hell, etc), and all of them seem healthy like normal people. I just wonder what the situation was in reality. Could 19th century people really used narcotics and stay healthy? And if so, how could they?