Jack Osbourne says that the worst part about his multiple sclerosis diagnosis is how "unpredictable" it is.

The 26-year-old recently became a father to baby Pearl and he appeared on "The Talk" with his fiance Lisa Stelly and mother Sharon Osbourne to talk about the illness.

The reality star told the show that the disease was not a "death sentence" like people may think.

"That's a huge misconception, people often think M.S. is Parkinson's or muscular dystrophy," he stated. "But it is actually very manageable and people live very normally."

"Another misconception is that it's a disease of age, the most common diagnosis is actually between 20 and 50. So little is known about it, and that's one of the huge reasons why I want to be so vocal about it."

But Jack added that there are still some parts of the illness he has to get used to.

"The toughest thing I am finding is that one minute I am fine and the next I am blind in one eye," he revealed. "That's the completely unpredictable thing about the disease."

Jack added that he was "having symptoms over the past three or four years and not realised it" including trouble with his bladder, stomach and numbness in his leg.