Does Idina Menzel have asthma?
Idina has never herself said that she has asthma. She very well could have asthma, she displays some of the common symptoms, but it could just be because in Wicked she sang up in the air surrounded by smoke and fog. I think that would make it hard for anyone to breathe, let alone sing. So basically, until Idina says herself that she has asthma, it is just a rumor.