Lady Gaga took a selfie in an oxygen mask late Wednesday, saying she'd been hospitalized for altitude sickness after her concert in Denver.
"Altitude Sickness is no Joke!" the pop star, 28, wrote on Instagram. "#hitThatHospitalS--t #artRaveDenver many true ravers crowd tonight."
The mile-high malady is hardly unusual in Colorado, of course. The Denver website has a whole section on how to deal with the altitude.
Something tells us Gaga might not have heeded tip No. 4, "Watch your physical activity," during her "artRAVE: The ARTPOP Ball" show.
The pop star's next concert, in Seattle on Friday, is scheduled to go on as planned.