ITV said the former Love Island contestant, 31, had been told by the programme’s medical team that it was not safe for her to return to camp.
Attwood becomes the first contestant to leave the show, which launched on Sunday night to an average audience of 9.1 million, according to overnight ratings from ITV.
A spokesman for the broadcaster said: “As a precautionary measure Olivia needed to leave the jungle to undergo some medical checks.
“Unfortunately the medical team has advised it is not safe for Olivia to return to camp as there needs to be a further investigation.
“She has been absolutely brilliant and she’ll be very much missed on the show.”
During the launch episode, Attwood was selected by the public to become a Jungle VIP, a Very Isolated Person, alongside radio DJ Chris Moyles, TV presenter and property expert Scarlette Douglas and Culture Club star Boy George.
After discovering the news, she said: “I am equal parts flattered and unnerved the public voted for me to be a VIP,” before guessing the voters know more about her fate than her.
This meant they spent their first night marooned on an island and also faced the first trial of the series.
Their challenge saw Attwood inserting her hand into small wall openings filled with worms in a bid to unscrew pipe fittings inside and stop the flow of water in chambers holding Boy George and Moyles.
Attwood shot to fame in 2017 on hit dating show Love Island and ahead of the new series said she was looking forward to debunking the misconception that she’s “high maintenance” and cannot cope without makeup.
Her representatives have been contacted for further comment.
The launch on Sunday night saw a new batch of 10 celebrities enter the Australian jungle for the first time since 2019, as the past two years were shot at Gwrych Castle in North Wales due to Covid-19 travel restrictions.
Hosts Ant McPartlin and Declan Donnelly confirmed there will be two extra arrivals to the camp, including former health secretary Matt Hancock.
The MP for West Suffolk is expected to join the camp in the coming days, as the presenters said they would be “rolling out the welcome mat for them soon”.
On Sunday, Prime Minister Rishi Sunak was quoted as telling The Sun he was “very disappointed” in the former health secretary because “MPs should be working hard for their constituents”.
On Monday, Business Secretary Grant Shapps said he will not be voting for Hancock to compete in the gruelling trials, and that he thinks his fellow Tory MP should be here “looking after his constituents”.
I’m A Celebrity… Get Me Out Of Here! continues on ITV and ITV Hub.