Zac Efron collapsed after overdosing on prescription drug oxycodone in January, it has been reported.

The former 'High School Musical' star allegedly binged on the powerful painkiller in addition to a cocktail of other drugs and alcohol during a wild night of partying in his hotel room and had to be resuscitated by guests at the party.

National Enquirer magazine obtained a photograph of Zac passed out in his suite at the Thompson Hotel in New York City on January 3

An eyewitness - who passed a lie detector test - told the publication: ''My worst fear was that he had died from an overdose. He went through a lot of pills even though it was clear he was entering a danger zone.''

As well as alcohol and oxycodone - known as ''hillbilly heroin'' - Zac is alleged to have consumed Adderall and marijuana.

The 25-year-old actor was so desperate to get his hands on some oxycodone tablets he asked his party guests to score some pills on the streets. The pills street value is $30 each and he asked for 40 individual tablets.

The source added: ''If he didn't have such a need for the oxy, I don't think he would have let us come into the room, he was like a junkie. He wanted the drugs so bad, and this was the only way he could get them.''

Zac appears to be serious about getting himself clean and completed a stint in a rehab centre approximately five months ago, but the insider warns a relapse could be serious for him.

The source said: ''I was scared for him. If he doesn't clean himself up, he'll be Hollywood's next big drug tragedy.''