On November 30, 2012, at age 26, Muniz was hospitalized after having a transient ischemic attack, and spoke about the experience on "Katie". He suffered a second attack a year later, on November 25, 2013. Muniz was interviewed in 2017 and asked about his health, and said he has had no issues. Although on October 9, 2017, it was revealed on "Dancing with the Stars" that he, in fact, has suffered significant memory loss, forgetting that he starred in his own films and shows including "Malcolm in the Middle".