Pope Francis has a respiratory infection and will need to spend "a few days" in hospital in Rome, the Vatican has said.
The pontiff had breathing difficulties in recent days but does not have Covid, the statement said.
He will need "a few days of appropriate hospital medical therapy".
"Pope Francis is touched by the many messages received and expresses his gratitude for the closeness and prayer," the statement added.
His closest staff, including security, were expected to stay the night at the Gemelli Hospital, a person with direct knowledge told the BBC earlier.
This is the busiest time of the year for Pope Francis, 86, with many events and services scheduled ahead of Easter weekend.
A Palm Sunday Mass is scheduled this weekend, and Holy Week and Easter celebrations next week.
He is also scheduled to visit Hungary at the end of April.
On Wednesday morning, he presided over his weekly general audience in St Peter's Square.
Though he looked to be in good spirits, he was seen grimacing as he was helped with getting into his vehicle, AFP news agency reports.
The pontiff has suffered from mobility problems related to his knee in recent months, forcing him to use a wheelchair.
He also underwent surgery to treat a colon problem at the same hospital in Rome in 2021. In January he said the condition had returned.
Despite his ailments, the Pope has remained active and has undertaken trips abroad this year. He visited the Democratic Republic of Congo and South Sudan in February.
In January, the Pope led the funeral of his predecessor Pope Benedict XVI - who was the first pope to step down voluntarily for centuries. He said this was due to ill health.
Pope Francis has previously indicated that he may also wish to follow in Benedict's footsteps in the event that his health deteriorated.
https://www.bbc.com/news/world-europe-65117270
