It will also allow him to rest after his campaign for the congressional elections.
Pacquiao's chief of staff, Jayke Joson, said in Manilla on Monday doctors had discovered the 31-year-old boxer had an ulcer during a routine check-up on Sunday. Pacquiao's family convinced him to stay on in a suburban Manila hospital for a few days.
"Really, Manny can only rest if you confine him to a hospital," Joson said, adding Pacquiao was receiving intravenous dextrose drips. "It's been so intense a campaign he missed some of his meals."
Pacquiao's promoters are working toward a possible bout with Floyd Mayweather, or another fighter, as early as November.
The champion's mother, Dionisia, said her son was well and may be discharged from the hospital later on Monday or Tuesday.
Pacquiao won a seat in the Philippine's powerful house of representatives, which he will assume on June 30. Aside from preparing to enter the political arena, Pacquiao is yet to complete advertisements for products ranging from food to sports items, Joson said.
US-based promoter Bob Arum has said he will soon start talking to Mayweather's camp about putting together the world's top two welterweights for a November 13 bout in Las Vegas or Texas.
Arum said he hoped to match Pacquiao against former welterweight champion Antonio Margarito if talks with Mayweather fall through.