The group of tourists had a buffet breakfast at their hotel in Da Nang before traveling to the nearby Hoi An Town; and had lunch at an out of town restaurant in Cham Islands.
In the afternoon, they began suffering stomach pain, vomiting and diarrhea and were sent to the emergency room at a hospital in downtown Da Nang.
Doctors diagnosed digestive disorders and acute gastritis. All the tourists victims are now in stable condition and were discharged from the hospital Tuesday.
The hospital reported the incident to city authorities.
In 2017, 46 tourists from Laos were hospitalized with food poisoning after having lunch at a restaurant in Da Nang. The restaurant was later fined VND25 million ($1,080) for failing to meet food safety standards.
Da Nang, usually considered Vietnam's third most important city after Hanoi and Saigon, is one of the top holiday destinations in the country. Last year it received 7.6 million tourists, 2.87 million of them foreigners, a 23.3 percent increase year-on-year.
Official data shows 91 cases of food poisoning affected more than 2,000 people in Vietnam in the first ten months of last year and killed 15 people.