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 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 shes still been going out drinking and living it up. She doesnt 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 shes overdoing it. She needs to take some time off. Otherwise shell 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 apologizing 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. Im really disappointed I couldnt 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. ES