Dizziness, nausea, lack of sweating, or confusion in hot weather — move the person to a cool area immediately, remove clothing, and cool them down with water; do not give water to anyone who is unconscious, and call 120 right away.

No cost involved.

National Weather Service (USA): Heatstroke is a "serious medical emergency." Its manifestations include body temperature higher than 103°F (39.4°C), confusion, slurred speech, and hot, red skin. Treatment involves calling emergency services immediately, moving to a cool place, cooling with cold water and wet cloths, and "do not give fluids." Symptoms of heat exhaustion include heavy sweating, fatigue, cool/clammy skin, and a rapid, weak pulse; treatment involves moving to a cool place, loosening clothing, and taking small sips of water; seek medical attention if vomiting, worsening, or if symptoms do not subside within 1 hours. Yunnan Provincial CDC reminds: immediately move to a cool, ventilated area, use cold, wet towels to cool down, provide saline drinks if conscious, and call emergency services immediately if symptoms are severe; severe heatstroke has an "extremely high mortality rate." China CDC reminds: cool down first, then transport; cool down within the "golden half-hour" after the patient loses consciousness. Conditional: young and middle-aged adults without underlying diseases can use cold water immersion for rapid cooling; the elderly and those with underlying diseases should spray water on the skin and rely on evaporation for cooling. The heatstroke guidelines updated in 2024 year by the Wilderness Medical Society state that cold water immersion is the most important method for treating severe heatstroke and provides the fastest cooling. If ice water is unavailable, use the coldest water at hand; if immersion is not possible, use water spraying combined with fanning, which provides a cooling speed of approximately half that of immersion.

US National Weather Service. Heat Related Illnesses. https://www.weather.gov/safety/heat-illness ; 云南省疾控局 (2026). 出现这些症状，你可能是中暑了. https://ynsjkj.yn.gov.cn/html/2026/jikongkepu_0719/2606.html ; 中国疾病预防控制中心. 高温天气，中国疾控中心提醒您谨防中暑：「如有条件可用冷水浸泡的方法对无基础疾病的青壮年快速降温。老人和有基础疾病的患者可向皮肤喷水通过蒸发降温。降温应遵循"先降温，后转运" 的原则」. https://www.chinacdc.cn/jkkp/ggws/hjyssj/202409/t20240906_296985.html ; 国家卫生健康委 (2010). 高温中暑预防知识要点. https://www.nhc.gov.cn/wjw/jbyfykz/201007/1edb19b7dd4e4bdf8da5ea45f4a64e23.shtml ; Eifling KP 等 (2024). Wilderness Medical Society Clinical Practice Guidelines for the Prevention and Treatment of Heat Illness: 2024 Update. Wilderness & Environmental Medicine 35(1_suppl):112S-127S. https://doi.org/10.1177/10806032241227924（正文站点拒绝自动抓取，具体推荐按荒野医学会官网的更新摘要核对：「cold water immersion … is the most important method of treating severe heat illness」「If CWI is unavailable, evaporative cooling is the recommended second-line treatment. … generally half as fast as CWI」https://wms.org/magazine/magazine/1540/Heat-Illness-CPG/default.aspx）；Lipman GS 等 (2019). 同指南 2019 版. https://doi.org/10.1016/j.wem.2018.10.004

Do not wait to "wait and see"; heatstroke can progress from dizziness to coma in just a few dozen minutes. Do not pour water into the mouth of an unconscious person, as they may choke. There are differing opinions on where to place ice packs. The China CDC recommends applying them to the neck, armpits, and groin, while the Wilderness Medical Society states that research does not show cooling effects from applying them to these specific areas. Their recommendation is that if ice packs are available, cover the entire body; if ice packs are insufficient, then place them on the cheeks, palms, and soles of the feet. Both sides agree that if conditions permit, use cold water immersion.