Christina Applegate is undergoing a string of tests after being misdiagnosed with multiple sclerosis.

The 54-year-old actor revealed in October that she was mistakenly told she had the progressive autoimmune condition in 2021, and she was going through a slow process of being tested for conditions that can mimic the symptoms of MS.

Speaking on her MesSy podcast – which she co-hosts with Jamie-Lynn Sigler – she said: “We’re going into square one, just doing some testing and going one by one of the sister diseases to MS.

“You’ve got RA (rheumatoid arthritis), lupus, Lyme disease, all these things can kind of mimic MS.

“So now I’m being tested for all that stuff slowly but surely.”

The Anchorman star previously admitted she was “not happy at all” about the misdiagnosis because she felt her health was worse than ever.

“(The doctor) came into my room and said, ‘Congratulations, you don’t have MS.’ I was, like, not happy at all. Everybody else was so happy,” she told her MesSy co-host.

“You don’t get misdiagnosed and then all of a sudden, ‘I’m better’.

“I haven’t gotten better, Jamie! If anything, I’ve gotten worse.

“So I’m back at square one where I don’t know what’s going on with me. And that’s going to be an online investigation that my doctors are going to be getting into just to find out what has been going on since 2021, why did this happen?”