The 26-year-old actor shared on Twitter that he has spent the past several days recovering from a serious medical crisis.
"[I] was in the hospital last Friday. I suffered a 'Mini Stroke', which was not fun at all," the former Malcolm in the Middle star tweeted.
Muniz continued: "[I] have to start taking care of my body! Getting old!"
The actor has shared no further information on his medical condition as of yet.
He is best known for starring in Fox's hit sitcom Malcolm in the Middle from 2000 to 2006.
Muniz most recently appeared as himself on James Van Der Beek's series Don't Trust The B---- in Apartment 23. He also guest starred in Tim Allen's Last Man Standing earlier this year.