Green’s Dictionary of Slang

against prep.

(drugs) addicted to or under the influence of a drug, usu. opium or heroin.

[US]W. Norr Stories of Chinatown 47: We were all up against the dope, and it was a great crowd that smoked [...] in those days. [...] Actors and actresses came down to Mott Street then to go against the hop.
[US]F. Hutcheson Barkeep Stories 17: ‘[H]e’s been agin de booze purty strong fer de las’ week and las’ night he was near due t’have de Brooklyn boys].
[US]W.J. Kountz Billy Baxter’s Letters 53: I have never been against the pipe, because I’m too young.
[US]H. Green Actors’ Boarding House (1906) 271: So yer agin the dope [...] I used to smoke onct in a while, but I didn’t never git no habit.
[US]J. Black You Can’t Win 60: They’ll wise up an’ you’ll lose her, or put her up against hop, an’ you’ll have a bum on your hands.
[US]B. Jackson Get Your Ass in the Water (1974) 133: The trouble with the Frenchman, he was up against the coke.