Jesy Nelson is to take an “extended” break from the pop group for “private medical reasons”, their publicist has said.
A statement didn’t give any further details about the 29-year-old’s condition.
It comes after Nelson recently missed the final of the girl group’s BBC One talent show, and their hosting of the MTV European Music Awards.
Little Mix’s latest album entered the UK chart at number two on Friday.
In a statement, the group’s publicist said: “Jesy is having extended time off from Little Mix for private medical reasons.
“We will not be issuing any further comment currently and ask media to please respect her privacy at this time.”
Nelson’s bandmates Leigh-Anne, Perrie and Jade were seen without her on the final of Little Mix: The Search on 7 November, and on the MTV EMAs the following night.bbc.com