But she says she does not know whether it is a bigger challenge than being a woman over 50 in Hollywood.
Garr, 56, was nominated for an Oscar for her role opposite Dustin Hoffman in Tootsie in 1983.
She noticed she was limping - the first symptom of her illness - 10 years ago, she told CNN's Larry King Live show.
But it was not until recently that she was finally diagnosed with MS, which attacks the nervous system, she said.
She told King that she had been relatively free of major problems so far.
"I'm going on with my life, I raise my daughter, I work," she said.
But she said she was now struggling to keep her acting career afloat.
"I worked the whole time but then later the work thinned out, but then I thought, 'What's worse in Hollywood, being handicapped or being a woman over 50?'
"You know it thins out anyway."
'Actor's protection'
She joked her lack of roles was like being hidden from the world in the FBI's witness protection programme.
"I used to say the William Morris agency put me in an actor's protection programme, it's really working very well," she said.
Garr began her career as a dancer, becoming a regular performer on the Sonny and Cher Comedy Hour.
Her first big film role was as Inga, the beautiful assistant in Young Frankenstein before playing Ronnie, the wife of the man who sees aliens in Close Encounters of the Third Kind.
She was given an Oscar nomination for best supporting actress for playing insecure actress Sandy opposite Dustin Hoffman in the hit comedy Tootsie.