Simpson had to reschedule her appearance on NBC's "Today Show" and also pulled out of a guest spot on CBS's "The Late Show with David Letterman.

"Today" host Matt Lauer announced during Tuesday's show Simpson, 26, had rescheduled her planned performance outside the New York studio for Friday.

Her rep, Rob Shuter, told People magazine that Simpson came down with laryngitis Monday.

"The timing could not have been worse," he said.

Doctors reportedly told Simpson, 26, if she fails to abide by orders to rest her voice, she could suffer permanent damage.