The 65-year-old bestselling author, who was diagnosed with breast cancer in March following a routine mammogram, was shocked to discover fake announcements of her death had been published online.
According to MailOnline, she took to social media platform X to blast the obituary before deleting her post.
"'I've taken the post about the obituary down, because I don't want people to think I'm upset by it," Fallon wrote.
"I'm not. Pissed off yes. But more, I just want people to know that any photos you see of me in hospital, looking sad or with tubes sticking out of me are 100 per cent fake – AI generated."
The fake obituary came not long after Fallon took to Instagram to share the good news with her followers that her surgery had been successful and doctors had "basically got it all".
She posted a video with her cat and told fans: "The surgeon said I can lift some weights so I'm starting with this one (the cat).
"Just a little update, all is good, yesterday I had my follow-up and they have basically got it all.
"What they haven't got is a clear margin around the edge of what they have taken so I am going to have to have another op.
"It will be just to make sure they get everything, which is a bit of a pain, but it isn't a worry – they just need to make sure they have a clear margin, so will be the exact same operation as last time."
In the caption, Fallon acknowledged the "fabulous" treatment she was getting and how lucky she was to get an early diagnosis.
"I've had so many conversations with lovely people who've come up to me in the street in the last couple of weeks and told me their own personal experiences, and it's totally rammed home both how different it is for everyone and also how important screening and early diagnosis really is," she wrote.
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