Zac Efron is a ''hero'' for going to rehab.

His 'Parklife' co-star Marcia Gay Harden has praised the ''brave'' actor - who has reportedly sought treatment for supposed cocaine and alcohol addictions earlier this year - and insisted he will motivate people to seek help in the future.

She told E! News: ''In my opinion, Zac Efron is a total hero. Him seeking help encourages other people with addictive issues to seek help. It's brave of him.

''I think only a coward lives in denial, and he is not a coward. He's a hardworking go-getter and I love him.''

Meanwhile, Zac's friend Rob Lowe recently defended his decision to go to rehab, noting that he must be ''serious about [his] recovery'' if his issues were kept quiet until after he'd left the treatment centre.

He previously wrote on Twitter: ''A thought: if you only find out a person has been to rehab weeks or months after they got out, they're probably serious about recovery.''

It has also been reported the star was ''happy'' and in good health, choosing to focus on his career.

A source had claimed: ''He's healthy, happy and not drinking. He's taking time to focus on working.''