The 88-year-old, who has been breathless in recent days and has delegated officials to read his speeches, was admitted following his morning audiences.
The pope, who had part of one of his lungs removed as a young man, has been experiencing breathing difficulties for over a week and has repeatedly asked aides to read his speeches aloud on his behalf.
Francis was hospitalized for three nights in March 2023 with bronchitis, which was treated with antibiotics.
In December of that year, he had to cancel a visit to Dubai for the United Nations COP28 climate change conference due to another bout of bronchitis.
The Argentine pontiff has faced various health challenges in recent years, including knee and hip pain, an inflamed colon, and surgery for a hernia.