Philip Seymour Hoffman Cause of Death -- Massive Drug OD ... Heroin, Coke, Rx Meds

Philip Seymour Hoffman was killed earlier this month by a deadly mixture of heroin, cocaine, and several other drugs -- this according to the NYC medical examiner.

The medical examiner just released the official cause of death -- listing "acute mixed drug intoxication" as the reason PSH passed away suddenly on February 2nd.

According to the medical examiner, the drugs in the actor's system at the time of his death were heroin, cocaine, benzodiazepines (anti-anxiety) and amphetamines (uppers like Adderall).

Mixing heroin and cocaine is often termed "speedballing." It's the same mixture that killed Chris Farley, River Phoenix, and John Belushi.