Looney was sent home after shootaround Wednesday due to an illness, Dalton Johnson of NBC Sports reports.
Looney was initially ruled out for Wednesday's game against Sacramento for rest purposes, but it appears he's in fact battling an illness. While the sickness shouldn't have an impact on his status for Golden State's regular-season opener against Phoenix on Oct. 24, Looney could also be held out of Friday's preseason finale against San Antonio.