Tabare Vazquez, who took over from Jose Mujica – "the world`s poorest president" in March, was flying from South America to France on Monday when the 17-year-old girl was taken ill.
She was returning from a hockey tournament in Buenos Aires when she ate a snack containing peanuts, which she was allergic to, and stopped breathing.
Her mother called for help, and the captain asked if there was a doctor on board. And Mr Vazquez, a 75-year-old doctor, offered to help. With his personal doctor, he calmed the girl, gave her an intravenous injection and oral medicine.
The pair were able to stabilise the girl, without the flight having to turn back.
Doctor said it was the third time Mr Vazquez had stepped in to give medical assistance on a plane: the first time on a flight to Asia, and the second was on a flight to Europe, when he helped an American woman who was having an asthma attack.
The mother of the French girl thanked Mr Vazquez and his assistant, on arrival in France.
She said the Uruguayan president had "saved the life" of her daughter.
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