We all know the air in Denver, Colorado is thin due to the high altitude, but who knew you could be hospitalized for it. Well, Lady Gaga did and shared a photo of herself in the hospital after her concert last night.

Jade Raven

Wearing an oxygen mask strapped over her mouth and nose, the pop star tweeted a photo of herself (check gallery) with the caption: “Altitude Sickness is no Joke! #hitThatHospitalS**t #artRaveDenver many true ravers crowd tonight.”

The singer had to receive medical treatment after suffering from altitude sickness following her show in Colorado for her ArtRave: The Artpop Ball tour.

According to Trip Advisor, altitude sickness is common for travelers who visit Colorado. Symptoms include making one feel dizzy, nausea or vomiting, a feeling of breathlessness, especially when exercising (hence her oxygen mask), loss of appetite, light-headedness and difficulty sleeping.

Hopefully Gaga feels better, and she can continue on with her tour.