2) Zac Efron

Teen heartthrob Zac Efron reportedly went into rehab in 2013 to battle cocaine addiction, a problem which caused his acting career to suffer. Speculation as to why Efron turned to substance abuse has revolved around girl problems, issues with his parents, and a dissatisfaction with his movie career. Though at first it was believed that the 25 year-old star was battling alcohol problems, then the news emerged that the hard-partying actor was dealing with a much more sinister drug.

Zac Efron
Zac Efron Dealt With His Cocaine Addiction In Rehab.

Not long after the High School Musical star had left the facility, a source reassured, "He's doing great. He's taking care of himself and it shows." Luckily, Efron's addiction was nipped in the bud before he could go totally off the rails, setting a good example for any of his fans dealing with similar issues.

Lindsay Lohan

For a time, actress Lindsay Lohan pretty much had a revolving door into rehab with her name on it. The embattled Mean Girls star has gone all out since her adorable child actress days by doing coke, struggling with alcohol problems, countless stints in rehab, violating probation and spending at least 90 days in jail.

Lindsay Lohan
Lindsay Lohan Is Out Of Rehab & Clean...For Now.

Though once it looked as though there was no light at the tunnel for the child star of The Parent Trap, Lindsay seems to currently have a handle on her issues, committing to sobriety, avoiding temptation and turning her attention to making her reality show on Oprah Winfrey's network, Lindsay, as successful as possible. Fingers crossed, LiLo!

Next Page: Nicole Richie, Macaulay Culkin.