You know how annoying it is to have dry, itchy eyes? Jennifer Aniston does too. "I was addicted to eye drops," the actress confessed to us. Aniston, 47, says her symptoms got so bad that she had trouble reading scripts. The culprit, she eventually learned, was dry eye, a condition that affects up to 30 million Americans. In a recent phone chat, the star (a paid spokesperson for the pharmaceutical company Shire) shared what it's like to think you have allergies and discover you have something else entirely.

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So when did you start to have issues with your eyes?

I’ve had dry eye for years, I just didn’t know what it was. I didn’t know that dry eye was a diagnosable condition until 8 months or a year ago. I just thought that these were my eyes and I had allergies. My eyes are light, so I thought they were more sensitive to the outside elements. I really didn’t know, and I was just constantly using eye drops. It got to the point when I was using eye drops two to three times every hour to feel relief because it was so painful and so irritating and itchy. It got in the way of the joys of my daily life. Reading scripts starts to become impossible. I was getting headaches. My eyes were swollen and irritated.

How did you figure out what you had?

I was giving an interview and the interviewer said, “Do you have anything you’re addicted to?” And as I was literally putting in an eye drop I said, “Well, eye drops!” A couple of weeks after that came out, Shire approached me and said that’s actually a condition called dry eye and let’s team up and do a campaign that creates awareness. It’s kind of debilitating. It’s a big pain in the butt. Myeyelove.com is the website where you can get information. And I went to my doctor and found out that I sure as hell did have dry eye. And that was such a wonderful relief like I can’t even explain to you to get myself weaned off the eye drops.

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Were you hooked on the Visine-type eye drops or the rewetting ones?

Everything! I just did everything. I’d get the strongest ones you could buy. And it’s like, These are gonna burn. The bigger the burn, the better the eye drop. Then you keep using them and they lose their effectiveness.  

Are there any triggers that make your symptoms worse?

Just the environment. If I was at the beach it would kick up. The pollen would just be a nightmare. Even in my sleep. I would wake up and didn’t know if I would wake up with irritated or swollen eyes because it would itch throughout the night.  It was really something I was dealing with all day long. So I was pretty grateful to find out it was a thing that could be remedied.

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So many people these days have issues with irritated eyes.

The girls in my office ... my girlfriends. When I told them that’s what I had, each one would turn to the other and say, "Oh my God, that’s what I have!"

Did you have trouble on film sets and photo shoots with the lights and the makeup? Have you ever had to take a break because of it?

Yes, I’ve had to let my eyes calm down because they are so itchy and red. And the makeup—sometimes there’s that glittery eye shadow? Forget about it. That is like little razors in my eyeballs. So when I finish my makeup, that’s the least ideal time to put in my eye drops, but that’s what I would have to do because they were irritated from the makeup.

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Do you have a worst "oh, no" moment when dry eyes really became a problem for you?

Photo shoots. Wind machines are not fun—trying to give an expression where you’re blinking and have tears streaming down your face. 

Do you think people don't even know dry eye is a thing?

I read a lot about what I need to look out for and take care of, and I thought I was up on everything. I didn’t know about it. We go to the dentist and the doctor to get our physical and do all those checkups. And I had to go to the doctor to get my eyeglasses checked, but if you don’t have glasses, you don’t think that we have to consider our eye health.

It can be stressful to deal with an ongoing health issue. What is your advice for others?

Reach out to friends for support, and ask questions. There are answers everywhere.

This article originally appeared on Health.com.