Rihanna Taken to Hospital, Tweets Picture of IV in Arm

                                                                         (Image Credit: Mike Marsland/Getty Images)

Pop star Rihanna was taken to the hospital Monday night and reportedly treated for a fever and the flu, but she's apparently fine now.

Before she went to the hospital, the "Birthday Cake" singer had attended the Met Costume Ball and looked stunning as she walked the red carpet in a long, fitted black leather gown by designer Tom Ford.

Some of her 18.5 million Twitter followers had been a little concerned when the singer's timeline went without regular updates Tuesday.  One fan tweeted the singer to ask what was going on, and the 24-year-old responded by  tweeting the photo of her arm hooked up to an intravenous therapy drip.

The Barbados-born singer, 24, didn't give any further explanation. Citing a source, E! reported Rihanna had had a fever and flu since last week and needed the treatment, but was fine now.

"There have certainly been instances where celebrities use the term exhaustion, what they really mean is rehab," longtime publicist and ABC News consultant Howard Bragman said.  "I think Rihanna was trying to send the message of, 'Look, I'm in the hospital, I'm trying to make myself better.'"

The hospital visit comes days after the pop star missed the final dress rehearsal for her "Saturday Night Live" performance because she reportedly was sick. The show's staff thought that Rihanna looked healthy when she did her live performance, though, according to TMZ.  Sources told the website that Rihanna had a doctor give her a penicillin shot before she took the stage.

"She's not one to stay at home at night and relax," Jennifer Peros, a reporter with US Weekly magazine, told ABC News.  "She's out partying at all the clubs around the world.  So I definitely think she may be burning the candle at both ends here. "

A previous bout of the flu forced Rihanna to scrap a show in Malmo, Sweden, in October.

"She really needs to slow down and focus on herself," consultant Bragman said.  "Taking care of herself, that's what's most important."