The pop singer is a celebrity Dj on London's Heart Breakfast show, but she was too sick to head into the studio to join her co-presenter Jamie Theakston.
She took to her Twitter.com page to promise listeners she will bounce back quickly, writing, "Thanks for all your lovely messages! I'm feeling better already. Listening to Heart London, miss you Jamie Theakston, see you tomorrow!"
Fellow ex-Spice Girl Melanie Chisholm tweeted, "Get well soon Bunton missed you on my wireless this morning."