Demi Lovato has revealed that she has a respiratory infection and has been coughing up blood.

The singer is currently on her North American Neon Lights tour, but it seems she has been feeling poorly.

The former X Factor USA judge said last night (March 11) on Twitter:

"The last thing I would EVER want to do is cancel a show, with that being said I'm super sick tonight so it may not be my best show BUT I'm SO excited to perform for you guys but I may need you to sing most of the show for me!!! Hahaha."

Lovato later posted a screenshot of a text message conversation she had with a friend that said she coughed up blood.

The 'Skyscraper' star then tweeted: "For all of you that are worried, I saw a doctor and it's just a respiratory infection.. And my phone is charging."

Lovato's next tour date meanwhile is due to take place on Thursday (March 13) at Auburn Hills, MI.