Frankie Muniz, who played the eponymous character in Fox’s hit sitcom Malcolm in the Middle, suffered a “mini-stroke” and has been in the hospital since Friday.

“I was in the hospital last Friday," Muniz said on Twitter (@frankiemuniz) Tuesday. "I suffered a ‘Mini Stroke’, which was not fun at all.”

A “mini-stroke” refers to a transient ischemic attack (TIA), in which blood is unable to reach the brain and causes symptoms similar to a stroke. While a TIA does not cause lasting damage, it could serve as a sign of a future stroke.

Muniz, 27, had been exercising and was going to his girlfriend Elycia Turnbow's mother’s house when the symptoms began setting in, according to People. Muniz was unable to see out of his right eye and later began experiencing pain, dizziness and numbness. He has been hospitalized in Phoenix, Ariz. since Friday.

"I consider myself to be very healthy," Muniz told People. "I'm home and trying to relax and get ready to get back to work. My biggest problem is I always want to be working, going non-stop. So it's a wakeup call to take a little time and relax a bit."

Even with these cautionary words, Muniz, who has acted sparingly since his Emmy-nominated work on Malcolm in the Middle, has an adventurous side that led him to try racecar driving, and more recently, playing drums for the band Kingsfoil. Muniz intends to go on Kingfoil's upcoming eight-date tour, which kicks off this coming weekend.