The club added: “Everyone at Newcastle United extends their best wishes to Eddie for a speedy recovery, and further updates will follow in due course.”
The statement did not give any further details of his illness or condition.
In Howe’s absence, assistant managers Jason Tindall and Graeme Jones will lead Newcastle for the visit of Ruben Amorim’s side to St James’ Park.
Tindall stood in for Howe at a pre-match news conference on Friday.
Last month, Howe guided Newcastle to their first domestic trophy for 70 years – and ended a wait for a major prize stretching back to 1969 – with a deserved Carabao Cup final win over Liverpool at Wembley.
Newcastle are currently seventh in the Premier League table.
Amersham-born Howe has been in charge of the Magpies since November 2021, when he succeeded Steve Bruce as the club’s head coach.
Newcastle have finished 11th, fourth and seventh in the past three seasons.
Howe has taken charge of 165 matches in all competitions for Newcastle, winning 84 drawing 36 and losing 45 of them.
Under Howe, the Magpies memorably beat Paris St-Germain in the Champions League group stage in 2023-24 campaign but failed to make it to the knockout stage.
He had two spells in charge of Bournemouth either side of brief stint at Burnley, and has been talked of as future England manager.
However, he said he was not interviewed by the Football Association to replace Gareth Southgate, with Thomas Tuchel appointed Three Lions boss last October.
