The Los Angeles Times reported that Stoll fell ill at his Hermosa Beach home.
Kings general manager Dean Lombardi told the Times that he visited Stoll in the hospital and the "bottom line is that he's fine. Now the issue is what caused it."
The Kings did not immediately respond to an Associated Press email seeking comment on Stoll's condition Wednesday.
The 31-year-old Stoll missed all but the first game of the Kings' second-round playoff series against the Sharks after suffering a concussion following a hit by San Jose's Raffi Torres. He returned in time for the Western Conference finals against the Chicago Blackhawks.
Stoll also suffered a concussion during the 2006-07 season while playing for the Edmonton Oilers.
Information from: Los Angeles Times, http://www.latimes.com