A group of tourists from Laos were rushed to hospital with food poisoning after having lunch at a restaurant in Da Nang on Saturday.
At midnight the same day, 26 tourists were sent to the emergency room where doctors treated them for stomach pains, vomiting, diarrhea and dizziness, and 20 more from the same group were admitted the following day suffering from the same symptoms.
Four of the victims were children, and the youngest was just two years old.
All of the victims are now in stable condition and have been discharged from hospital.
Authorities are investigating the incident.
Da Nang welcomed 5.5 million tourists in 2016, 1.67 million of whom were foreigners, official data shows.
The city issued food safety licenses to over 3,300 qualified food courts and restaurants in early 2017. The highest fine for breaking regulations is VND200 million ($9,000).