Green’s Dictionary of Slang

fix up v.2

[ext. of fix n.3 (1)]

1. (US drugs) to inject heroin or morphine.

[US]H. Green Actors’ Boarding House (1906) 272: Now I’m fixed up.
[UK]A.B. Reeve Constance Dunlap 298: I must fix up a bit.
[US]K. Kolb Getting Straight 3: You want to fix up this afternoon?
[UK]M. Dibdin Dark Spectre (1996) 21: While the mother is waiting for the water to heat, she decides to fix up.

2. to give someone, usu. an alcoholic, a drink.

[US]J. Thompson Alcoholics (1993) 26: You’ve got to fix me up, Doc. Boy, if I don’t get a drink fast I’m going to fall apart.

3. to give (or sell) someone some narcotic; the image is of dealing with withdrawal symptoms.

C.B. Yorke ‘Snowbound’ in Gangster Stories Oct. n.p.: ‘Like to sniff a deck? Fix you up — steady your nerves’.
[US]J.E. Schmidt Narcotics Lingo and Lore.
[US] in S. Harris Hellhole 145: Take a seat there, Cindy, and I fix you up. You want a little shot now?
[US]V.E. Smith Jones Men 217: We gon fix you up.