Dizziness, nausea, lack of sweating or confusion in high heat — move to shade immediately, remove clothing and apply cool water to cool down; do not give water to anyone who is unconscious, call 120 right away

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United States National Weather Service: Heatstroke is a "serious medical emergency." Its manifestations include body temperature above 103°F (39.4°C), confusion, slurred speech, and hot, red skin. Treatment is to call emergency services immediately, move to a cool place, use cool water and wet cloths to lower temperature, and "do not give fluids." Manifestations of heat exhaustion include heavy sweating, fatigue, cool and clammy skin, and rapid, weak pulse; treatment is to move to a cool place, loosen clothing, and take small sips of water. Seek medical attention if vomiting, worsening, or if symptoms do not subside after 1 hour. The Yunnan Provincial Center for Disease Control and Prevention advises: immediately move to a cool, ventilated area, use cold, wet towels to lower temperature, provide drinks containing salt to those who are conscious, and call emergency services immediately for severe symptoms. It also states that severe heatstroke has an "extremely high mortality rate." The China CDC advises: cool the body first, then transport; cool the body within the "golden half-hour" after the patient loses consciousness. If conditions permit, young and healthy adults without underlying diseases can use cold water immersion for rapid cooling, while the elderly and those with underlying diseases should have water sprayed on the skin to cool via evaporation. The 2024 updated heat illness guidelines from 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 spraying and fanning, which is approximately half as fast as immersion. The National Institute for Occupational Safety and Health (NIOSH) states that during a heatstroke episode, body temperature can rise to above 106°F (approx. 41°C) within 10 to 15 minutes. The symptoms it lists include "hot, dry skin, or heavy sweating." The 2014 version of the heatstroke guidelines from the China CDC lists manifestations of heatstroke as "red, hot, and dry skin without sweating," and treatment requirements include "do not give the patient water to drink"; if the patient vomits, turn them onto their side to keep the airway clear.

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；US CDC/NIOSH. Heat-related Illnesses：「When heat stroke occurs, the body temperature can rise to 106°F or higher within 10 to 15 minutes」「Hot, dry skin or profuse sweating」. https://www.cdc.gov/niosh/heat-stress/about/illnesses.html；中国疾病预防控制中心职业卫生与中毒控制所 (2014). 公众高温中暑预防与紧急处理指南（2014 版）. https://niohp.chinacdc.cn/sndt/201405/t20140530_97623.htm

Do not wait to "wait and see"; during heatstroke, body temperature can rise to above 41°C within ten-odd minutes. Heatstroke may involve no sweating, or it may involve heavy sweating; NIOSH lists both, so do not let it pass just because the person is still sweating. Do not give water to someone who is not fully alert; if they vomit, let them lie on their side. There are different views on where to place ice packs. The China CDC says to apply them to the neck, armpits, and groin, while the Wilderness Medical Society says research does not show that applying them to these specific areas has a cooling effect. The Wilderness Medical Society's recommendation is that if ice packs are the only cooling method available, cover the entire body, and if ice packs are insufficient, then place them on the cheeks, palms, and soles of the feet. Both sides state that if conditions permit, use cold water immersion.