- Heatstroke is a medical emergency; the WHO notes it has a high case fatality rate.
- Thailand's Department of Disease Control (DDC) lists very high body temperature, hot flushed skin, lack of sweating, confusion and loss of consciousness among its warning signs.
- For suspected heatstroke, call 1669 or get the person to hospital immediately, and start cooling them while you wait.
- Heat exhaustion usually improves within about 30 minutes of rest, cooling and fluids; if it does not, treat it as heatstroke.
- Older people, young children, pregnant women, outdoor workers, athletes and people with chronic illnesses are most at risk.
Heat in Thailand
Thailand's hot season, roughly March to May, brings temperatures that can reach the low 40s °C in parts of the country, and high humidity makes heat harder to shed at any time of year. In March 2026 the Department of Disease Control warned of heatstroke risk as the hot season began, aiming its advice particularly at older people, young children, pregnant women, outdoor workers, athletes and people with chronic illnesses such as heart disease and obesity.
Visitors are often caught out because they are not acclimatised, are more active than usual, and may be drinking alcohol. Long walks around temples at midday, island hiking, running and Muay Thai training are common triggers.
Heat exhaustion or heatstroke?
Heat exhaustion is the earlier, less severe stage. The NHS lists headache, dizziness and confusion, loss of appetite and feeling sick, heavy sweating with pale clammy skin, cramps, fast breathing or pulse, a high temperature and intense thirst. It is not usually serious if the person can be cooled down within about 30 minutes.
Heatstroke happens when the body can no longer control its temperature. The DDC's warning signs include very high body temperature, hot and flushed skin, lack of sweating, dizziness, nausea and vomiting, a racing heartbeat, confusion, weakness and loss of consciousness, and it notes that seizures or incoherent speech can occur. The WHO describes heatstroke as a medical emergency with a high case fatality rate, and the strain on the body can damage the heart and kidneys.
The key difference for a bystander is the brain: any confusion, unusual behaviour, slurred speech, a seizure or reduced consciousness in the heat should be treated as heatstroke.
First aid for suspected heatstroke
Call 1669 or get the person to hospital immediately. Then start cooling straight away, following the DDC's advice: move them into shade or a cool, ventilated place, lay them flat and loosen tight clothing. Cool the body with cold, wet cloths on the neck, armpits, head and body, and use a fan to speed heat loss. Cold packs to the neck, armpits and groin can help.
If the person is unconscious but breathing, the DDC advises placing them on their side to keep the airway clear. Do not give anything to drink to someone who is confused, drowsy or unconscious. If they are unresponsive and not breathing normally, start CPR if you are able to and follow the 1669 call handler's instructions; use an AED if one is available.
This guide summarises published public-health guidance. It is not a substitute for first-aid training or for the instructions of the 1669 call handler or a doctor; if in doubt, call 1669.
First aid for heat exhaustion
For someone who is alert and able to drink, the NHS advises moving them to a cool place, getting them to lie down with their feet slightly raised, giving plenty of water (sports or rehydration drinks are fine), and cooling their skin with cool water, a cold pack or a fan. Stay with them until they are better.
They should start to feel better within about 30 minutes. If they do not improve, if they become confused or lose consciousness, or if they have a seizure, call 1669: this is heatstroke. Even after recovery, take the rest of the day easy and avoid going straight back into the heat.
Staying safe in the heat
The WHO advises avoiding strenuous activity during the hottest part of the day, staying in the shade, drinking water regularly, wearing light clothing and using cool showers or a damp cloth to keep your body cool. Plan sightseeing and exercise for early morning or evening, and build up activity over your first few days.
Alcohol and some medicines, including certain blood pressure tablets and diuretics, can make it harder to cope with heat; ask your doctor or pharmacist if you take regular medication. Never leave children or anyone vulnerable in a parked vehicle, even briefly. Check on older relatives and neighbours during heat warnings.
In the heat
- Avoid strenuous activity in the middle of the day, especially in your first few days.
- Drink water regularly; carry it with you.
- Treat confusion, collapse or a seizure in the heat as heatstroke and call 1669.
- Cool a heatstroke patient while waiting: shade, wet cloths, fan, cold packs to neck, armpits and groin.
- Put an unconscious but breathing person on their side; give nothing by mouth.
- If heat exhaustion has not improved within about 30 minutes, call 1669.
Frequently asked questions
What is the difference between heat exhaustion and heatstroke?
Heat exhaustion causes symptoms such as heavy sweating, dizziness, headache and nausea, and usually improves within about 30 minutes of cooling and fluids. Heatstroke is a medical emergency in which body temperature control fails; confusion, collapse, seizures or loss of consciousness are warning signs.
What should I do if someone has heatstroke in Thailand?
Call 1669 or get them to hospital immediately. While waiting, move them somewhere cool, lay them flat, loosen clothing and cool them with cold wet cloths and a fan, as Thailand's Department of Disease Control advises.
Should I give water to someone with heatstroke?
Only if they are fully alert and able to swallow. Do not give drinks to someone who is confused, drowsy or unconscious.
When is the hot season in Thailand?
The hot season is roughly March to May, but heat and humidity can cause illness at any time of year, especially with exercise.
Who is most at risk of heatstroke?
The DDC highlights older people, young children, pregnant women, outdoor workers, athletes and people with chronic illnesses such as heart disease and obesity.
Sources
- World Health Organization — Climate change, heat and health fact sheet
- Asia News Network (The Nation) — Thailand warns of heat stroke risk as country enters hot season, 16 March 2026
- NHS — Heat exhaustion and heatstroke
- Department of Disease Control, Ministry of Public Health (Call Center 1422)
- GOV.UK — Thailand travel advice: Getting help
