- O (2001). Steroids, Cocaine.
- Once Upon a Time in America (1984). Opium.
- One False Move (1992). Cocaine
- One Perfect Day (2004). Cannabis, painkillers, amphetamines and MDMA.
- Ong-Bak (2008). Opium.
- On the Road (2012). Cannabis, benzedrine, morphine and alcohol.
- The Opium Eater (2011). Opium.
- Orange County (2002). Amphetamines, Painkillers, cannabis, MDMA.
- Over The Edge (1979). Cannabis and LSD.
- Out of the Blue (1980).
- Outside Providence. (1999). Cannabis.
Read more about this topic: List Of Drug Films