LONDON — Queen Elizabeth II was hospitalized Sunday over an apparent stomach infection that has ailed her for days, a rare instance of ill health sidelining the long-reigning monarch.
Elizabeth will have to cancel a visit to Rome and other engagements as she recovers, and outside experts said she may have to be rehydrated intravenously.
Buckingham Palace said the 86-year-old queen had experienced symptoms of gastroenteritis and was being examined at London’s King Edward VII Hospital — the first time in a decade that Elizabeth has been hospitalized.
‘‘As a precaution, all official engagements for this week will regrettably be either postponed or cancelled,’’ the palace said in a statement. Elizabeth’s two-day trip to Rome had been planned to start Wednesday.
The symptoms of gastroenteritis — vomiting and diarrhea — usually pass after one or two days, although they can be more severe in older or otherwise vulnerable people. Dehydration is a common complication.
The illness was first announced Friday, and Elizabeth had to cancel a visit to Swansea, Wales, on Saturday to present leeks — a national symbol — to soldiers of the Royal Welsh Regiment in honor of Wales’ national day, St. David’s Day. She instead spent the day trying to recover at Windsor Castle, but appears to have had trouble kicking the bug.
A doctor not involved in the queen’s treatment said that if medical officials determined that she is losing too much fluid, she would be rehydrated intravenously.