Amanda Seyfried says she thought she had a brain tumor

Actress Amanda Seyfried arrives at the Producers Guild of America Awards in Beverly Hills, California Jan. 26, 2013. (Reuters)

Amanda Seyfried has opened up about her mental health battle, saying she initially had fears she had a brain tumor.

The "Mean Girls" star, 30, told Allure magazine that she has been taking anti-anxiety medication for her Obsessive Compulsive Disorder (OCD) since she was 19.

“Yeah. I’m on Lexapro, and I’ll never get off of it. I’ve been on it since I was 19, so 11 years. I’m on the lowest dose,” she said. “I don’t see the point of getting off of it. Whether it’s placebo or not, I don’t want to risk it. And what are you fighting against? Just the stigma of using a tool?”

She added, “A mental illness is a thing that people cast in a different category [from other illnesses], but I don’t think it is. It should be taken as seriously as anything else,” she said. “You don’t see the mental illness: It’s not a mass; it’s not a cyst. But it’s there. Why do you need to prove it? If you can treat it, you treat it.

“I had pretty bad health anxiety that came from the OCD and thought I had a tumor in my brain,” she said. “I had an MRI, and the neurologist referred me to a psychiatrist.”

Seyfried explained, “As I get older, the compulsive thoughts and fears have diminished a lot. Knowing that a lot of my fears are not reality-based really helps."

Seyfried even said she didn’t put a stove into on a rental property she was renovating because she gets nervous about house fires.

“I always worry about people and how they use stoves. Which is just a controlling thing,” she said. “[It’s] about the gas. You could so easily burn down something if you leave the stove on. Or the oven.”

Seyfried revealed last month that she is engaged to "The Newsroom" star Thomas Sadoski after just six months of dating.

The pair fell in love after starring together in the comedy "The Last Word." Sadoski was previously married to Kimberly Hope, while Seyfried had been dating actor Justin Long.

This article originally appeared on News.com.au