Opium and cocaine were in widespread use in the early 20th century.
So very true. Sherlock Holmes' stories are full of that stuff. And opium was already widespread way before that. For those interested, I strongly recommend reading "Confessions of an English Opium Eater", by Thomas de Quincey. BTW, the Beatles' song "Happiness is a warm gun" comes from one chapter of that book, I think.
I've seen Parke-Davis 1920's ads for morphine, featuring hypodermic syringes in jewel boxes. How the world has changed.