The singer was due to perform at the Sprint Centre in Kansas City last night and in St Louis tonight but has been forced to cancel both of the dates due to the severe allergic reaction to antibiotics.

Doctors have placed her on medical rest to help speed up her recovery.

She tweeted: "Kansas I promise Im as heartbroken as you are. I wanted so badly 2 b there 2night. Not being with yall makes me feel s**ttier than I already do.

"Mr. Octopussy & some amazing Drs are taking good care of me."

Today she also hit back at people on Twitter who have criticized her for the cancelations saying: “humans can b so selfish. if any1 thinks id rather b layin n a hospital bed than doing what i love on stage theyre fuckin LAME. im miserable.

"I can't get a hold of my team because it is so early so I want to be the one to tell my fans especially the ones trekking to get there.

"The hospital is sayin i wont b released today therefore Im not going 2 make it 2 St Louis. Im so sorry but somethings are outta my control."