The Fireworks singer has postponed gigs in Chicago and Minnesota which were due to be held on July 8th and 9th respectively.
According to MTV News, Russell Brand's wife has suffered an 'attack of food poisoning leading to severe dehydration'.
She said sorry to her legions of fans via Twitter and rescheduled both of the California Dreams tour dates for August.
'I apologise to my fans in Chicago and the Twin Cities for not being able to perform this weekend, but I am going to return in a few weeks to give them the very best show ever!' she wrote.