Miley, who's allergic to penicillin, says that while she wasn't given that particular drug to fight the flu, she was prescribed a medication in the same drug class that caused a severe allergic reaction.
"They gave me this medicine and I was on this medicine for five days. It's all good and then on the sixth day I just woke up and it was ... so scary. I had basically been poisoning myself with something I didn’t know I was really scary allergic to," she explained. "I never thought I'd get stuck in there as long as I did. I basically thought I'd be stuck for a night, and I was actually there for five or six days."
And what was the worst part of her hospitalization?
"Honestly just not being out on the road," she said. "I would feel good … [and ask doctors] 'Can I go? Can I get back on the stage?' That was the hardest part. … I was just crying because I was so bored."
Though Miley, 21, assured fans that she's feeling much better and is most likely in the clear.
"I should be all good, but what was the worst is that this reaction can happen from five to 27 days," she explained. "But I've been really good, and now, I just have to be more careful."