Dengue Fever in Chiang Mai: Symptoms, Hospital, Prevention
A high fever for more than 2 days needs a prompt doctor visit, with paracetamol only and no NSAIDs. Severe signs usually come as the fever falls, in a critical phase of about 24 to 48 hours. Chiang Mai cases peak from May to October.
A falling fever is not the end of dengue. The severe symptoms usually come as the fever falls.
Dengue numbers and season: Thailand and Chiang Mai
Thailand had 16,094 dengue cases from 1 January to 22 July 2026. By 15 September 2026 the count was 25,026 cases and 39 deaths.
Dengue counts for Thailand in 2026 from the DDC releases of 27 July and 15 September, checked 13 October 2026; no Chiang Mai count was found.Tap to enlarge diagram ↗
The September briefing says the count is 1.8 times lower than in 2025 but still trending up, especially in the South. DDC named Satun, Phuket, Nakhon Nayok, Ranong and Trang as the five provinces with the highest rates in the latest four weeks.
No Chiang Mai figure for 2026 appears in either release. Call the DDC hotline on 1422 for a provincial count.
When Chiang Mai sees dengue
The DDC epidemiology report says cases are most numerous during and after the rainy season, May to August. A study of Chiang Mai surveillance data for 2015 to 2024 puts May to October in the highest-risk group of months. It puts February to May in the lowest. Rainfall and humidity tracked the case count; temperature did not.
Symptoms and the fever curve
Dengue starts with sudden high fever, headache, body aches, pain behind the eyes, nausea, vomiting, severe abdominal pain, loss of appetite or a red rash. The fever lasts about 2 to 7 days.
Low platelets make bleeding easy, for example from the gums or the nose. In the first days a blood test may look normal or only slightly abnormal. Three in four infected people usually have no symptoms.
A high fever lasting more than 2 days needs a prompt doctor visit. Count from the first day of fever. Go earlier if the fever does not go down, vomiting increases, gums bleed, skin spots appear or the person becomes drowsy.
Dengue warning signs from the DDC release of 27 July 2026 and the DDC dengue note of 2020, checked 13 October 2026.Tap to enlarge diagram ↗
The July 2026 DDC release repeats the 2-day rule and the warning signs. The critical-phase detail below comes from the DDC dengue note of December 2020.
Getting tested in Chiang Mai
A Chiang Mai private lab lists a dengue package at THB 350 with results in 30 minutes. It has three parts.
The NS1 antigen test looks for the virus itself in the first 1 to 3 days of infection. The IgG/IgM test looks for antibodies from 3 to 5 days. A blood count checks the platelets.
The Mahidol Road branch is open daily from 07:00 to 20:00. Ask for NS1 if the fever is in its first days.
The day the fever falls
The severe symptoms usually come as the fever falls. Patients may think they have recovered and skip the visit. As the fever falls, vomiting and abdominal pain may continue.
The critical phase mostly lasts about 24 to 48 hours after the fever falls. Spotting it quickly and treating correctly cuts the case fatality from 10 percent to 1 percent.
Who is at higher risk
The main risk factors for death are obesity, an underlying disease, delayed treatment and taking NSAIDs. The fatality rate was highest in people aged 60 and over and in those aged 40 to 49.
In an emergency
The Thai emergency medical number is 1669. The hospital contacts are at the end.
What to take for the fever
Take only paracetamol with a fever. Avoid NSAIDs such as diclofenac, ibuprofen and aspirin. Avoid pain and anti-inflammatory drugs that irritate the stomach, the NSAID group.
Thai FDA material calls the NSAID group dangerous drugs that a doctor or pharmacist prescribes. The pharmacy guide covers the pharmacy counter.
The Aedes mosquito bites in the daytime, most in the 2 hours after sunrise. Cases usually rise much higher in the rainy season, when Aedes mosquitoes increase.
Cover water containers tightly, add larvicide sand, turn over unused containers and clear rubbish around the home.
Use DEET at 20-50% or picaridin at 5-20% on exposed skin.
An Aedes aegypti mosquito, the species that carries dengue.
The vaccine
DDC calls the dengue vaccine an option that may reduce the risk of severe illness and says to consult a doctor before vaccination. The DDC epidemiology report adds that it is not in the national immunisation programme but is offered at some clinics and hospitals.
The vaccine on offer is Qdenga. It is given twice, 3 months apart, to anybody aged 4 to 60 whether or not they had dengue before. Pregnant women and breastfeeding mothers should not have it.
Prices and clinics, read on 13 October 2026:
Lanna Hospital’s online shop sells the Qdenga four-strain vaccine at THB 2,600 for 1 dose, for ages 4 to 60. Ask what the price covers.
Chiangmai Ram Hospital’s online shop lists a dengue vaccine package at THB 2,800 for 1 shot and THB 5,500 for 2 shots.
CM Mediclinic offers Qdenga at its Chiang Mai clinic, in two doses 3 months apart. Ask the clinic for the price.
Chiangmai Ram Hospital
The hospital is at 8 Boonruangrit Road, Si Phum, Mueang, Chiang Mai 50200, tel. 052-004699. Its emergency line is 052-004601.
Chiangmai Ram Hospital 8 Bunrueang Rit Rd, Si Phum, Mueang Chiang Mai District, Chiang Mai 50200, Thailand · Open in Google Maps (opens in a new tab)The street front of Chiangmai Ram Hospital.
Bangkok Hospital Chiang Mai
The address is 88/8-9 Moo 6, Nong Pa Khrang, Mueang Chiang Mai, Chiang Mai 50000, and the number is 1719 for local calls only. Its Trauma Center of Excellence is open 24 hours, 7 days a week on +66 (0)52 089 888.
Bangkok Hospital Chiang Mai 88/8-9 Lampang - Chiang Mai Superhighway, Tambon Nong Pa Khrang, Mueang Chiang Mai District, Chiang Mai 50000, Thailand · Open in Google Maps (opens in a new tab)The lobby of Bangkok Hospital Chiang Mai.
Maharaj Nakorn Chiang Mai Hospital
The hospital is at 110 Inthawarorot Rd., Sri Phum, Mueang Chiang Mai District, Chiang Mai 50200. Its Emergency Room is open 24 hours a day, 7 days a week. The EMS service line is +6653-938-777.
Maharaj Nakorn Chiang Mai Hospital 110 Intrawarorot Rd, Si Phum, Mueang Chiang Mai District, Chiang Mai 50200, Thailand · Open in Google Maps (opens in a new tab)The trauma centre block at Maharaj Nakorn Hospital.
1Take paracetamol for the feverWith a fever, take only paracetamol and avoid NSAIDs such as diclofenac, ibuprofen and aspirin.
2See a doctor after more than 2 daysA high fever lasting more than 2 days needs a prompt doctor visit.
3Watch the day the fever fallsThe severe symptoms usually come as the fever falls, in a critical phase of about 24 to 48 hours.
4Go promptly if warning signs appearIf the fever does not go down, vomiting increases, gums bleed, skin spots appear or the person becomes drowsy, see a doctor promptly.
5Cut mosquito breeding at homeCover water containers, add larvicide sand, turn over unused containers and clear rubbish around the home.
Not confirmed: No 2026 Chiang Mai dengue count was found; the DDC releases give national figures. Call the DDC hotline on 1422. No hospital price list for a dengue test was found; the test price below is a private lab's. Whether Bangkok Hospital Chiang Mai and Maharaj Nakorn stock a dengue vaccine is not stated.
There is no published 2026 Chiang Mai count. Thailand had 16,094 cases from 1 January to 22 July 2026 and 25,026 by 15 September 2026.
When should I see a doctor for a fever?
A high fever lasting more than 2 days needs a prompt doctor visit.
Can I take ibuprofen for dengue fever?
Take paracetamol only and avoid NSAIDs such as diclofenac, ibuprofen and aspirin.
Why is the day the fever drops risky?
The severe symptoms usually come as the fever falls, which leads patients to think they are better. The critical phase mostly lasts about 24 to 48 hours.
Which mosquito carries dengue, and when does it bite?
The Aedes mosquito bites in the daytime, most in the 2 hours after sunrise.
Is there a dengue vaccine, and where in Chiang Mai?
Qdenga is given in 2 doses 3 months apart to ages 4 to 60. It is not in the national programme but some clinics and hospitals offer it. Lanna Hospital's shop lists THB 2,600 for 1 dose; CM Mediclinic offers it without a listed price.
When is dengue season in Chiang Mai?
Chiang Mai surveillance data for 2015 to 2024 put May to October in the highest-risk group of months and February to May in the lowest.
How much is a dengue test in Chiang Mai?
A Chiang Mai private lab lists a dengue package at THB 350 with results in 30 minutes. It includes an NS1 antigen test for the first 1 to 3 days of infection.
Do most people with dengue have symptoms?
Three in four people infected usually have no symptoms.
Who dies of dengue in Thailand?
The fatality rate was 0.16 percent to 22 July 2026, highest in people aged 60 and over and in those aged 40 to 49.
General information checked against the sources listed above, not legal advice for your situation. Rules and office practice change; confirm with the immigration office or a licensed adviser before you act. See how guides are checked.
