WASHINGTON—The Pentagon has begun an investigation into Navy Rear Adm. Ronny Jackson, who served as the personal physician for three presidents until misconduct allegations emerged last week, dooming his bid to become secretary of veterans affairs.
The Defense Department’s Office of Inspector General is conducting the probe into allegations against Dr. Jackson and will decide afterward what further investigation or action should be taken, Pentagon spokesman Tom Crosson said in a statement.
The Pentagon didn’t detail the specific allegations being reviewed or their source. Dr. Jackson was accused by Sen. Jon Tester (D., Mont.), the senior Democrat on the Senate Veterans’ Affairs Committee, of mistreating lower-ranking employees, drinking to excess on overseas trips, and handing out prescription drugs.
Mr. Tester has said the allegations were based on complaints by active-duty and retired military officers who had worked in the White House Medical Unit and who had come to the committee.
The Navy and the Navy Bureau of Medicine and Surgery have their own Offices of Inspector General and could be tasked with the investigation.
Dr. Jackson gave up his position as President Donald Trump’s personal physician when he was nominated to be VA chief. In a statement announcing his decision to withdraw from the cabinet-level nomination, Dr. Jackson called the allegations “completely false and fabricated.”
Dr. Sean Conley, a Navy commander who has worked at the White House since December 2016, has been named to take his place as the president’s physician. Dr. Conley joined the Navy in 1998, military records show.
Dr. Jackson, after dropping his bid to win Senate confirmation, resumed his work at the White House Medical Unit, White House officials said, but no longer leads that unit.
U.S. defense officials have said the Navy only learned of the allegations presented by Mr. Tester during Dr. Jackson’s nomination battle. During his tenure aAt the White House, Dr. Jackson was under the supervision of the White House Military Office and largely outside the traditional Navy chain of command.
Military officials last investigated Dr. Jackson in 2013, when the Navy Bureau of Medicine and Surgery looked into charges that Dr. Jackson, then a captain, and a fellow Navy captain had created an unhealthy environment at the White House office they led while Dr. Jackson served as the president’s physician, defense officials said. Dr. Jackson and his colleague were allowed to stay in their jobs.
Mr. Trump nominated Dr. Jackson in March to the rank of two-star rear admiral. The Navy said he remains a candidate for the second star, which would be conferred by the Senate.
Write to Nancy A. Youssef at Nancy.Youssef@wsj.com