"Can I say it sucked balls?" the 51-year-old actress declared on Wednesday's The Kelly Clarkson Show.
Applegate learned she had MS while filming the latest season of Netflix's Dead to Me.
"There's four different kinds of MS so not everyone is the same. Everyone's symptoms are different, everyone's experience with it is different," Applegate prefaced to Clarkson.
"Shooting the show was the hardest thing I'd ever done in my life because I was diagnosed during shooting. I didn't know what was happening to me," the Married With Children alum continued. "I couldn't walk. They had to use a wheelchair to get me to set. I was freaking out until someone was like 'You need an MRI.' And then, I found out on a Monday after work that I had MS, you know, a disease that I am going to have for the rest of my life."
Looking back, Applegate realized she had "very small symptoms" four years prior to an official diagnosis. The actress had a weak leg and felt very tired on set. She previously spoke about dealing with balance issues.
"It presented itself a few years ago," Applegate shared.
Applegate made her first public appearance since revealing her MS diagnosis on. Nov. 14 when she received a star on the Hollywood Walk of Fame. She was set to receive the honor in 2020, but it got pushed due to the pandemic.
"Now my life is a different story," Applegate told Variety. "People are going to see me for the first time as a disabled person, and it's very difficult. So, for me, two years ago would have been so much better!"
Applegate shared her health news with the world in Aug. 2021, saying she had learned about it just a couple months prior. Production on the third and final season of Dead to Me was halted for five months. However the cast and crew, including Applegate's on and off screen best friend, Linda Cardellini, rallied around her to finish the shoot.
"It was like torture — and they felt like they were torturing me, too," Applegate explained. "But I was like, ‘No, no, no, no, no, no: We have to finish this story... We've got to get [fans] their closure too.' So, if that meant me having to take a break in the middle of the day so I could go sleep — or me just leaving because I couldn't do anymore — then that's what we had to do."
MORE: Christina Applegate chats with Kelly Clarkson