Rachel Bilson Drug Use: 'The O.C.' Star Admits To Using Drugs And Alcohol Prior To Making It Big

Rachel Bilson hit it big when she landed a role on The O.C. in 2003, and luckily, she had gotten all of her wild ways out of her system beforehand.

Although Bilson's co-star, Mischa Barton, let loose after being cast, Bilson kept calm and focused on work -- which she claims was the result of her having already been down that road.

"I grew up in L.A. and did all that when I was younger," Bilson revealed to Health Magazine, according to E! News. "I went to the clubs and did all the drugs and alcohol."

At the time she began starring on The O.C. as Summer Roberts, Bilson was 21-years-old and single, but after hitting it off with her on-screen love interest, Adam Brody (who is now married to Leighton Meester), the pair began dating and continued with their relationship for three years.

"I got it out of my system, so by the time I was on The O.C., I was like, ‘Wow, I can just enjoy this,'" she recalled. "Then I started dating a costar, so it was more of a domesticated thing; you're just home or with friends—and not out to party."

Although Bilson and Brody were in a relationship for the majority of their time on the show, they eventually split in 2006, one year prior to the show's ending. Following her relationship with Brody, Bilson moved on with fellow actor, Hayden Christensen.

In 2007, Bilson and Christensen began dating after meeting on the set of Jumper, and one year later, they became engaged. 

"I've been in my relationship for seven years, so we've grown up together in a way," Bilson told Health Magazine of her fiance. "This is my partner, my support, just there for me no matter what. And vice versa."