A statement released by her publicist says the Friday show at Allstate Arena in Rosemont, Ill., has been rescheduled to Aug. 21 and her Saturday show at St. Paul's Xcel Energy Center is now set for Aug. 23.
The statement says the food poisoning led to severe dehydration. She performed ill at Summerfest in Milwaukee Thursday.
John Boler, vice president of sales and marketing at Summerfest, says Perry wasn't feeling well when she arrived. He says a doctor attended to her during the day and the performance.
He says she performed beautifully despite being sick.
Perry apologized but said she plans to give fans the best show ever when she returns.