Miley Cyrus is "miserable" in hospital.

Writing on her Twitter page, the 21-year-old star, who was due to perform at the Scottrade Centre in St. Louis, Missouri, said: "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 (tbc)

"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 (sic)."

The 'Wrecking Ball' hitmaker also lashed back at suggestions she didn't want to perform.

She tweeted: "humans can b so selfish. if any1 thinks id rather b layin n a hospital bed than doing what i love on stage theyre f**kin LAME. im miserable (sic)"

A source told gossip website TMZ.com that Miley was spotted shopping with her mother, Tish Cyrus, not long before her allergic reaction.

The singer was allegedly given antibiotics because she is run down from partying and the recent death of her dog, Floyd, earlier this month.

A source claimed she has been "an emotional mess" since the dog was killed by a coyote on April 1 and was unable to sleep, adding: "She's been off the rails since this happened."

But her father Billy Ray Cyrus said she is doing well, tweeting: "Everyone and everything is o k. Thank you so much for your prayers and love. (sic)"

Miley kicked off her 'Bangerz' world tour in February and is due to wrap it up in Madrid, Spain on June 17, 2014.