As temperatures climb with the arrival of summer, heat-related illnesses and emergencies become increasingly common. More than 700 people die from extreme heat every year in the United States alone, and the risks are growing.¹ Understanding how to recognize, prevent, and respond to heat emergencies can mitigate these risks.
Heat illness exists on a spectrum. Heat cramps (painful muscle spasms most often in the legs and abdomen, accompanied by heavy sweating) are frequently the first warning sign that the body is struggling to cope. If the situation is not addressed, it can escalate to heat exhaustion, which presents with heavy sweating, weakness or fatigue, cool and clammy skin, a fast weak pulse, dizziness, nausea, and headache. At this stage, moving to a cooler environment, loosening clothing, and hydrating are essential. Medical attention should be sought immediately if vomiting occurs or symptoms persist beyond an hour.²
The most dangerous heat illness is heat stroke, a life-threatening emergency defined by a combination of a core body temperature above 40°C (104°F) and changes in mental status, including confusion, slurred speech, or loss of consciousness.³ Anyone displaying these symptoms requires emergency medical care without delay. While waiting for help, the priority is rapid cooling: the person should be moved to a cool environment and have cool, wet cloths applied or be immersed in cool water.
The National Weather Service recommends to avoid giving fluids to someone with heat stroke,² as they may not be able to swallow properly and are at risk of aspiration. Active cooling, particularly cold-water or ice-water immersion, is strongly preferred over passive methods when possible. The goal is to bring core temperature below 39°C within 30 minutes of symptom recognition. Critically, common fever medications such as acetaminophen and NSAIDs have no role in heat stroke and should be avoided as treatment options, as the condition is not driven by the same physiological mechanisms as fever.³
Prevention remains the most powerful tool. The CDC recommends staying in air-conditioned spaces during peak heat hours, drinking fluids regularly without waiting for thirst, wearing loose and light-colored clothing, and never leaving children or pets in parked vehicles. Certain groups face substantially higher risk: adults over 65, young children, and people with chronic conditions such as heart disease, diabetes, obesity, or mental illness are limited in their ability to sense and/or respond to rising temperatures.¹ People taking medications that impair the body’s ability to regulate heat should speak with their doctor before summer outdoor activities in order to prevent heat-related emergencies.
The broader context of climate change makes these precautions increasingly urgent. Research has found that heat mortality events that would have previously been expected to occur once every 100 years in the climate of the year 2000 are now expected every 10 to 20 years and will become even more frequent as global temperatures continue to rise.⁴ Heat-related deaths in adults over 65 have increased by 167% compared with the 1990s, and in 2023, people worldwide were exposed to an average of 50 more days of health-threatening heat than would have occurred without anthropogenic climate change.⁵
With the risk of heat emergencies growing each year, it is increasingly important to understand how to protect oneself and others during summer months. Awareness and preparation are essential, and being able to identify the warning signs and take action quickly may save a life.
References
- Centers for Disease Control and Prevention. Protect Yourself From the Dangers of Extreme Heat. CDC Climate and Health (2024). https://www.cdc.gov/climate-health/php/resources/protect-yourself-from-the-dangers-of-extreme-heat.html
- National Weather Service. Heat Cramps, Exhaustion, Stroke. National Oceanic and Atmospheric Administration(2022). https://www.weather.gov/safety/heat-illness
- Barletta, J. F. et al. Society of Critical Care Medicine guidelines for the treatment of heat stroke. Crit. Care Med.53, e490–e500 (2025). https://doi.org/10.1097/CCM.0000000000006551
- Lüthi, S. et al. Rapid increase in the risk of heat-related mortality. Nat. Commun. 14, 4894 (2023). https://doi.org/10.1038/s41467-023-40599-x
- Romanello, M. et al. The 2024 report of the Lancet Countdown on health and climate change: facing record-breaking threats from delayed action. Lancet 404, 1847–1896 (2024). https://doi.org/10.1016/S0140-6736(24)01822