“Once Upon a Time” star Jennifer Morrison struggles with something on set — and it has nothing to do with Hades and the Underworld. The normally private actress, who is also known for her roles in “House” and “How I Met Your Mother,” is opening up about her experience with migraines.

Morrison’s “Once Upon a Time” character, Emma Swan, may seem invincible when facing fairytale villains, but that’s not always the case off-camera. Three years ago she began experiencing migraine attacks.

“I was actually driving which was what was really scary,” Morrison told International Business Times of one of her first migraine attacks. “If you start to feel like you have blurred vision while you’re driving obviously that’s not a good situation. Luckily I was able to pull over right away and stay pulled over for as long as it was lasting. But then that turns into the pain, which lasts for a long time.”

Morrison revealed that there have been times where she’s had to report to set after having a migraine for 24 hours. However, since her migraine trigger is from bright flashes of light, there are also instances where being on set can actually cause an attack.

“Usually I’m able to push through but obviously it’s not great when you can’t read your script or you can’t quite focus on the face in front of you. So it takes an extra kind of endurance to push through the symptoms and to try to stay as present as possible at work.”

Despite the harsh symptoms that accompany a migraine — blurred vision, throbbing pain, sensitivity to light and nausea — Morrison, 37, prides herself in not letting her migraines affect her work. When she feels an attack coming on she tries to stay in a darker room and avoid long exposure to light. She’s also cut back on her driving, which she found was a migraine trigger when she was overtired or exhausted. But with that being said, she knows that’s not always the case for others who suffer from migraines, and that’s why she partnered up with Teva Pharmaceuticals' MoreToMigraine.com campaign.

“It’s one of those things that if I had known about that when I first started experiencing some of the symptoms I would have been more aware of what the problem was,” the actress explained of the resources on the site. “When it first started happening, especially because mine started with the blurred vision, I wasn’t sure what it was. So then I was panicking on top of it like, ‘Oh my gosh, what is happening to me.’ And if I had a resource like MoreToMigraine.com where I could have gone there and looked at the possible symptoms, and look at the possible causes and things I can bring up to my doctor, then I think I would have had at least the comfort of knowing where to start.”

Jennifer Morrison Jennifer Morrison has teamed up with MoreToMigraine.com to help others suffering from migraines get the resources they need. Photo: courtesy of Teva Pharmaceuticals

 “It’s one thing for me where I’m just dealing with it for my own self and trying to push through on set, but we’re talking about moms with kids, with babies, with toddlers, dealing with migraines that are debilitating,” she continued. “And that would be really hard. You can’t stop being a caretaker even though this is happening. Or people who have really high-pressure situations where they’re in a courtroom and suddenly get a migraine. These are really debilitating circumstances for certain peoples lives, so I think that it impacts everyone’s life a little bit differently.”

Since first experiencing migraine attacks, Morrison has worked with her doctor to help limit them. And she’s certainly not letting them affect her career or stop her from living her life.

“Maybe it’s just partially my personality, but I have a determination to find a way to push through and find a solution that works for me. I’ve never missed a day of work, I’ve never had them have to have an insurance day for me. I find a way to push though. That’s the choice that I’ve made and I guess maybe I’ve been lucky that I’ve been able to find a way to push through. The things I want to do creatively are not going to be altered by that.”

That creative desire Morrison has led her to recently start her own production company, Apartment 3C Productions. Her first project, “Sun Dogs,” is with writer Anthony Tambakis, who she previously worked with on “Warrior.” And although Morrison enjoys being in front of the camera, she’ll actually be behind the camera for “Sun Dogs,” sitting in the director’s chair for her first feature film.

“The one thing you’re always searching for as a director is great content and [Tambakis’] scripts really are just so special. I read [“Sun Dogs”] and loved it and we spend the next, I guess six months, talking about the little tweaks and changes we wanted to make … He’s just been absolutely wonderful. He’s a great collaborator and he’s so supportive. He’s just been totally by my side through this whole thing and really championed me for this. I feel really grateful for that. Now we’re in the process of casting and finalizing everything and starting to do location scouting. It’s all becoming very real.”

Once Upon a Time Emma & Hook Jennifer Morrison, pictured here with co-star Colin O'Donoghue, who plays Killian Hook, stars as Emma Swan on ABC's “Once Upon a Time.” She's also jumping behind the camera for "Sun Dogs," her first full length directorial debut. Photo: ABC