By SARAH FITZMAURICE
Felling fragile: Selena Gomez was looking weary as she arrived at the hospital in LA. on Saturday
She was rushed to hospital on Thursday night after complaining of nausea and a severe headache and when she returned on Saturday Selena Gomez was looking tired and run down.
The 18-year-old singer cut a frail figure as she was seen entering the hospital in Burbank, California, dressed in grey tracksuit bottoms and a yellow and white striped vest.
Selena was clutching a jumper and the hospital bands could be seen on her wrists.
The Wizards of Waverly Place star was rushed to hospital on Thursday night following an appearance on U.S. television.
Her spokesman told MailOnline that the 18-year-old singer and actress was suffering nausea and a severe headache.
Under the weather: The 18-year-old actress was dressed in a pair of grey jogging bottoms and a yellow striped vest as she returned to the hospital
While Selena, who stayed at the hospital on Thursday night, has undergone a number of tests the cause of her illness is still a mystery.
There have been reports that she was suffering from food poisoning, however a spokesperson for the star was unavailable for comment earlier today.
Her illness meant the actress was forced to pull out of a promotional appearance for her new film, Monte Carlo on Friday.
Her boyfriend Justin missed an Ice Hockey on Friday night after hearing Selena had fallen ill.
The Canadian singer didn't show up to the game after reserving a block of seats at Vancouver's Rogers Arena to watch the Stanley Cup finals Friday night, E! News reported.
Mystery illness: The cause of her illness is not yet known but Selena has undergone a number of tests while at the hospital
Well wishes: Boyfriend Justin Bieber tweeted a message of support
And Selena was supposed to make an appearance at Santa Monica Place Center Plaza on Sunday with her band The Scene, but the event had to be cancelled due to Selena’s ill health.
The performance of Who Says and a fan Q&A session was rescheduled for today, but it is unclear if Selena is well enough to perform.
Hours earlier from being rushed to hospital Gomez had seemed to be on good form during the Tonight show, telling the host how her boyfriend Justin Bieber - who today tweeted his sweetheart a Twitter message of support - has already 'passed the mom test'
She said her mother Mandy had given Bieber, 17, the thumbs up.
No signs: Before Selena was rushed to hospital on Thursday she had appeared on the Tonight Show with Jay Leno
Animated actress: The 18-year-old had spoken to the chat show host about her boyfriend Justin Bieber
'Has your mom met Justin Bieber?' Leno asked, to which the smiling former Disney star replied: 'Yes.'
'And how did that go? Ok? Did she like him?' asked Leno.
'He passed the test," the Texas-born star responded.