Doctors kept her in overnight and conducted "routine tests" on Friday morning (10Jun11), before allowing her to go home.
Gomez was spotted heading back to the hospital less than 24 hours later, and her boyfriend Bieber and best pal Lovato have shown their support for the ailing star by taking to their Twitter.com blogs to wish her well.
Bieber, who went public with his romance with Gomez earlier this year (11), simply tweeted "#getwellselena", while Lovato wrote, "praying for you friend.. Love you.. #getwellselena."
As a result of her illness, Gomez was forced to pull out of an event promoting her new movie Monte Carlo at the Santa Monica Place Center Plaza on Sunday (12Jun11) and the show was rescheduled for Monday (13Jun11).
Gomez is also due to headline Good Morning America's Summer Concert Series event in New York's Central Park on Friday (17Jun11).