The 83-year-old former "Mary Tyler Moore Show" star was taken off stage while performing at the Marquette Pavilion in Gary, Ind., on Tuesday night, Sherman said.
Asner was taken by ambulance to a Chicago-area hospital, according to Sherman.
Asner has been touring the nation portraying President Franklin Delano Roosevelt in a one-man show "FDR" for over three years.
The Associated Press contributed to this report.
