A spokeswoman for the "Wizards of Waverly Place" star says Gomez "wasn't feeling well and was taken to the hospital" and is undergoing "routine tests." She did not specify Gomez's condition.
The 18-year-old singer-actress was promoting the upcoming film "Monte Carlo" on the talk show.
Gomez's appearance to promote the film at a Santa Monica, Calif., mall on Friday was canceled.
The hospitalization was first reported by TMZ, which said Gomez suffered from nausea and a headache before going to a Los Angeles-area hospital.
