Complaining of severe stomach pain, Pasco Sheriff Lee Cannon was taken by ambulance to Columbia New Port Richey Hospital on Wednesday.
Cannon, who was sick with a possible flu virus last week, was expected to be kept for observation and tests overnight, said sheriff's spokesman Jon Powers.
"I would love to tell you he will definitely be out for a few days but you know him," Powers said.
"At the very least, we don't expect to see him here (today)."
Despite feeling sick for much of last week, Cannon, 52, continued to make appointments and work late at the office, Powers said. He missed only one day of work last week, Powers said.
On Wednesday, Cannon had a doctor's appointment in the morning, then went to have lunch with his wife, Jeanne.
When he returned, he began experiencing severe pain and decided to go to the hospital, Powers said. Doctors are not certain what was causing the pain, Powers said.
In the sheriff's absence, one of the four majors is typically appointed to oversee the agency. Because Cannon is expected to be released today, no one has been asked to step in, Powers said.
"We have rescheduled all of his appointments but expect him back at the agency within a few days," Powers said.