Rihanna has been ordered by doctors to curb her partying lifestyle.

The 'Cheers (Drink to That)' singer was forced to pull out of a show in Malmo, Sweden, on Monday, October 31, 2011 after being hospitalised with a bout of flu, and her medical team are concerned she is going out too much while on tour.

A source told The Sun newspaper: “Rihanna is running on empty but she's still been going out drinking and living it up.

“She doesn't have any down time where she can completely relax. She spends most of her time in the studio, on stage or in clubs. Doctors are worried she's overdoing it.

“She needs to take some time off. Otherwise she'll be vulnerable to more illness.”

Rihanna, 23, posted a picture of herself with a drip in her arm from the hospital, and later released a statement apologising to fans for missing the show.

She said: “I am sorry to everyone who was coming out to my show in Malmo. I was so excited to perform for you all.

“It would have been a great time. So much better than being sick with the flu, ugh. I'm really disappointed I couldn't be there.”

Stars have rushed to wish Rihanna well with friend and mentor Jay-Z and US 'X Factor' judge LA Reid sending her flowers.

Rihanna's 'Loud Tour' resumed on November 01, 2011 in Stockholm, Sweden. - Bang Showbiz