Zac Efron has allegedly been to rehab twice this year.

New reports claim the '17 Again' actor checked himself into a treatment facility to cure his supposed cocaine and alcohol addiction for a second time in April, after experiencing a major relapse.

Sources told TMZ the star initially sought help for his apparent two-year struggle with class A drugs in March, but was forced to return in April when he started using again on the set of Seth Rogen's comedy 'Neighbours'.

Zac is said to have acted ''erratically'' during filming, barely showing up to the shoot and causing worry amongst the cast and crew, leading him to seek care for a second time.

The gossip website also allege Zac's struggles stem from his personal and professional problems, suggesting the actor is disappointed his film career hasn't gone in the direction he hoped since his initial global success of Disney's 'High School Musical' franchise.

Another catalyst is said to be the Hollywood hunk's ''girl issues'' with sources saying he was led astray by ''a bad group of friends'', who he has since cut out of his life.

Zac appears to have turned his life around this summer, walking the red carpet at a premiere for his new thriller 'Parkland' at the Toronto International Film Festival on Monday (16.09.13).

He told reporters: ''I'm good, real good.''