Liz was due to appear on the ITV1 show with her bandmates, Kerry Katona and Natasha Hamilton, but began to feel really poorly backstage.
Medics then decided the singer was too unwell to appear on air and decided it was best if she abandoned the scheduled interview slot and returned home.
Liz had previously told her Twitter followers: "On my way to @thismorningitv with a very croaky voice. Looks like there'll be a lot of nodding at my end of the sofa. :) @AtomicKOfficial."
She has since added: "Thank you to all the lovely people behind the scenes @thismorningitv, my girls & the medics for looking after me today. xxx."
Going ahead without their bandmate, Kerry told hosts Phillip Schofield and Christine Bleakley: "[Liz] is not very well. She was a trooper, she came in this morning but, unfortunately, she's got a bit of a viral infection and she had to go home."
Along with Natasha, the girls then spoke about their forthcoming Atomic Kitten: Greatest Hits tour, which has come off the back of their successful Big Reunion in 2013.
Mum-of-five Kerry admitted: "I never thought in a million years, after having all my kids, they would get to see me in Atomic Kitten - and that's the reason why I'm here in the first place. It's so nice. I feel young again!"
Natasha, who has four children, added: "We always say about the band, 'It gets us out the house!' It's like a part time job.
"We love being mums and love being at home with the children, but it's nice to get all glammed up. We appreciate it more and we're in control more."
Last year, Natasha and her boyfriend - 5ive star Ritchie Neville - welcomed daughter Ella into the world.
She added: "Life has changed so much since The Big Reunion, so many great things have happened. I've got my beautiful little daughter now, Ella.
"She's five months and my three boys absolutely adore her and having a little sister."
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