Queen Elizabeth II left a London hospital on Monday after a one-day stay for treatment of a stomach infection.
The 86-year-old was admitted Sunday after experiencing symptoms of gastroenteritis. Officials said she has remained under close observation just as a precaution. It was her first hospitalization in 10 years.
All of the queen's official engagements for next week have been canceled or postponed.
The symptoms of gastroenteritis, which are commonly vomiting, nausea and diarrhea, usually pass after one or two days, although they can be more severe in older or otherwise vulnerable people. WebMD characterizes the illness as what many people often dub the "stomach flu," and dehydration is a common complication.