The 30-year-old "Black Hawk Down" and "Pearl Harbor" star was admitted to Cedars-Sinai Medical Center in Los Angeles early Sunday. His illness was described as a flare-up of an ongoing medical condition.
"He has had a lot of testing," publicist Susan Patricola told Usmagazine.com Friday. "They released him, and they are trying to figure out what it might be. He is fine."
Patricola did not say exactly when Hartnett left the hospital.
Celebrity Breakups and divorces of 2014 [PHOTOS]