12/21/2011 at 08:00 AM EST
, Naya Rivera plays fresh-faced cheerleader beauty Santana Lopez – but away from the cameras, the actress admits it has taken a lot to achieve her picture-perfect look.
"I had really bad skin for awhile earlier this year," Rivera said Tuesday on the set of her Proactiv
shoot, where she revealed to PEOPLE exclusively that she is the brand's new spokesperson. "It sort of just came out of nowhere. It was like adult acne, and I was like, I've had great skin my entire life. How am I dealing with this now at 24?"
The actress says once her problem surfaced, filming Fox's hit show became less comfortable.
"It was pretty embarrassing going to work every day and having to be on camera and having the makeup artists be like, 'Oh, what's going on?' " She explains. "[My Glee
costars] were really supportive. I would always go around and talk about it. It was a point of insecurity for me. But I'm glad I got it fixed, I'll say that."
Although the L.A. native says she has "scarring issues" from her breakouts, she's at least been able to stop the problem from getting worse, thanks to the help of the line she now endorses.
"I used Proactiv and it really did work for me," she says with a big smile. "It helped me out, so I got in contact with the company and told them I would love to share my story. So I showed them photos and they said, 'This is great.' Wait till people see my pictures. That's all I have to say. I definitely have the photos to prove [I had a problem]."
It took "a couple of months" before she started seeing improvements, but now Rivera wants other girls battling with the same issue to know: "It's a process, but it does get better."