Halsey battled a "terrible" case of food poisoning shortly before their appearance at a festival in the U.K. over the weekend.
The Without Me singer, who uses both she/her and they/them pronouns, took to Instagram Stories on Saturday to share that they had been very sick prior to their gig in Leeds, England on Friday night.
"No idea how I'm still alive after my Leeds set," they wrote. "I have terrible food poisoning STILL! It started yesterday at 2pm and I somehow made it on stage (after the medical team at the festival were soooo helpful!)"
Halsey noted that they have played shows under "messed up conditions" in the past, but this was the "worst in recent memory".
"Felt like I was on Jupiter the whole time," the 27-year-old continued. "Thank you for being so cool and letting me basically do whatever just to survive the set! You guys would have been an unreal crowd under ANY circumstances let alone those. Time to rest now 4 Reading tomorrow."
Later, Halsey also shared footage showing them receiving medical attention, and in a voiceover, described being sick as "exceptionally not f**king chill".
After resting all day Saturday, Halsey planned to perform at the Reading Festival on Sunday night.
Back in May, the star revealed that they have been battling a variety of medical issues, including Ehlers-Danlos syndrome, but was abiding by a "treatment plan".