Residents at the Pascha Bay hotel in Alanya fell ill on Sunday evening and into Monday morning, with several ambulances turning up to take the ill to hospital.
The Swedish tourist staying at the hotel travelled with charter trip company Fritidsresor. A representative told the TT news agency that the youngest child is one year old, but that the children suffering from diarrhoea and vomiting are all ages.
“Twenty-one children are still in hospital,” Fritidssresor spokesman Mathias Bergendahl said.
The young patients are on drips and receiving anti-biotics.
While the Turkish health authorities run tests to determine the cause of the outbreak, sources said they had already ruled out salmonella.