Evan Agostini, Associated Press
Heath Ledger

Actor Heath Ledger died from an accidental overdose of six different drugs — painkillers and sedatives, the New York medical examiner said Wednesday, leading doctors to warn of the dangers of mixing prescription drugs.

The 28-year-old film star died "of acute intoxication" from the combination of two strong painkillers, two anti-anxiety medicines and two sleeping aids, according to the medical examiner's office.

Among the drugs found in his body were oxycodone, a painkiller sold as OxyContin and used in other pain relievers such as Percodan and Percocet. Others included drugs sold as anti-anxiety pills Valium and Xanax, which are sedatives.

The medical examiner and police wouldn't identify the medications Ledger had in his apartment when his body was discovered on Jan. 22, nor would they discuss who had prescribed them.

The Drug Enforcement Administration is investigating how Ledger obtained the medications and whether they were prescribed illegally.