According to the city's Centre for Disease Control (HCDC), 17,718 dengue cases were recorded between the start of 2026 and May 31, despite the city only recently entering the rainy season.
The figures were released at a public health seminar on dengue prevention organised by HCDC and Takeda Vietnam on Saturday.
Le Hong Nga, deputy director of HCDC, said dengue cases had been reported across all 168 communes, wards and special administrative zones in the city.
More than half of all infections were among adults, with the highest incidence recorded in the 11-15 and 16-30 age groups, indicating that the disease is no longer concentrated mainly among children.
Nga said identifying transmission risks was the first step in protecting households, warning that mosquito breeding sites around homes continued to pose a significant threat.
Health experts said misconceptions about dengue remained common, with some patients underestimating the disease or attempting self-treatment, including intravenous fluid infusions without medical supervision.
Pham Van Quang of Children's Hospital 1 said severe dengue complications are most likely to occur between the third and seventh day of illness, often after the fever subsides.
These can include dengue shock syndrome, severe bleeding and multiple organ failure affecting the heart, liver, kidneys and brain.
Doctors urged people to seek medical attention immediately if they experience warning signs such as severe abdominal pain, persistent vomiting, cold extremities, bleeding gums, nosebleeds or reduced urination.
Experts urged households to spend about 10 minutes a week eliminating mosquito breeding sites by removing standing water and cleaning potential breeding areas.
HCDC said it was promoting a double shield approach that combines mosquito and larva control measures with vaccination to reduce infections, severe cases and the overall burden of dengue fever.
