Trivia: When Tyrone is making mashed potatoes, the prison guard standing behind him is played by the novelist Hubert Selby Jr., on whose novel the film is based.
Trivia: Director Darren Aronofsky included nearly the entire cast of his debut film Pi in Requiem for a Dream. Abe Rabinowitz, Arnold the shrink, Nurse Mall, the mailman and the E.R. Doctor were all in Pi. Joanne Gordon even plays the same character Mrs. Ovadia (in Pi she was the evil landlady and is one of Sarah's friends in Requiem). Also his mother Charlotte Aronofsky is Mrs. Miles, another of Sarah's friends; and his father Abraham Aronofsky is the newspaper reading man on the subway.
Trivia: Director Aronofsky requested that Leto and Wayans refrain from having sex and consuming sugar so that their cravings and drug addiction would appear genuine on-screen.
Answer: Both heroin and cocaine are used in the film. Cocaine is used mostly by Marion, and also injected at least once but heroin can also be snorted. The route of administration stereotype does not hold to all drug users (except for alcohol, which can pretty much only be taken by mouth) The fact the prison guard says "He won't be putting any more DOPE in that arm" - dope is slang for heroin in New York, not coke - and the severe withdrawals as soon as the drug is unavailable suggests heroin is used by all three major characters. The pills used by Sara are preludin, dexedrine and diazepam (according to the novel which the film is based on) but I do not know what the "Blue" pill (the one she takes in the afternoon) is.