Lanning will be replaced by Alyssa Healy and will not be replaced in the squad, with Australia to find cover from the Australia A touring party.
On the advice of Cricket Australia medical staff, Lanning will tend to a medical issue which requires management from home.
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Lanning, 31, last year took an extended break from the game for personal reasons and leaves a big hole in Australia's batting order.
"It's an unfortunate setback for Meg and she's obviously disappointed to have been ruled out of the Ashes; it's a significant series for the team and she'll be missed, but she understands the need to put her health first," Cricket Australia head of women's performance Shawn Flegler said.
"Meg will remain at home where she will continue to work with medical staff with the aim to return to playing as soon as possible.
"We ask that Meg's privacy is respected at this time."
All-rounder Tahlia McGrath has been promoted to vice-captain for the multi-format series.
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