Search: how long before roofies take effect
Why: In Lifetime movies, the dizzy spins seem to happen almost immediately.
Answer: Somewhere between 10 and 30 minutes! The effects peak within 2 hours, and they may persist for more than 8 hours, depending on the dosage!
Source: OHS, Yahoo! Answers
The More You Know: Rohypnol is a trade name. The generic name of the drug is Flunitrazepam. It's marketed as a strong hypnotic and powerful sedative, anticonvulsant, anxiolytic, amnestic, and skeletal muscle relaxant drug. Before it's mashed up and poured in your lycheetini, it looks like this: