Lady Gaga in Toronto with dog Asia

Lady Gaga is seen leaving her hotel along with her dog Asia in Toronto on July 8, 2014. She signed autographs and took pictures with fans who were waiting outside her hotel.

Splash News

She may do what she wants with her body, but she's got to be careful. 

Lady Gaga Instagrammed a photo of herself in the hospital Wednesday night. The ARTPOP singer apparently got altitude sickness after her show in Denver, Colo., sending her to the hospital.

Alongside the pic -- which showed Gaga donning an oxygen mask and full stage makeup -- the singer wrote, "Altitude Sickness is no Joke! #hitThatHospitalSh– #artRaveDenver many true ravers crowd tonight."

Assuming she gets better quickly, Lady Gaga will continue her artRave tour in Seattle on Friday night, which will be the last U.S. stop of her current run. After a quick stop in Canada, she'll head to Japan.