Heat and Human Health: What Pharmacists Need to Know

Extreme heat events cause preventable deaths across the United States each year.^1,2 These events—days of heat and often humidity abnormally high based on geographic region—are responsible for the highest number of weather-related deaths, harming more people than floods, tornadoes, and hurricanes combined.^2,3 It is estimated that about two-thirds of the American population are exposed to a greater-than-expected number of extreme heat days,⁴ and the number of extreme heat events is expected to increase in the future.^2-4

There are many potential health threats associated with rising temperatures, either from exposure to higher temperatures or through associated environmental changes, such as those associated with greater humidity (which raises the heat index and impairs the body’s ability to cool via sweating) and reductions in air quality.^2-11 These threats can vary in their severity as well as in their short- and long-term impact, exacerbating health conditions associated with acute illnesses (eg, heat rash, heat cramps, heat edema, heat syncope, heat exhaustion, heat stroke, sunburn, and severe burns from hot surfaces), as well as chronic illnesses (eg, cardiovascular and respiratory conditions, kidney disease, adverse pregnancy outcomes, disrupted sleep, and impacts to mental health).^5-9 Human health also is impacted indirectly through the environmental impacts related to extreme heat (eg, crop failure and water supply reduction). ^5-9

Extreme heat may harm any of our patients.^2,3,6-9,12 However, some are at higher risk based on 3 major factors: exposure to heat (eg, patients who work outdoors, are unhoused, cannot afford air conditioning, or live in urban heat islands); sensitivity to heat (eg, infants and young children, patients who are pregnant, older adults, and those with certain chronic conditions, taking certain medications, or using drugs/alcohol); and ability to respond and prepare to heat events (eg, patients unable or unwilling to seek health care or go to a cooling center during a heat wave).^2,3,6-9,12

As accessible and trusted health care providers, pharmacists have important roles to play in helping patients mitigate the impact of heat on their health. The CDC provides guidance to clinicians to help their patients create a heat action plan to stay safe on hot and humid days. First, review the patient’s background to determine vulnerability to heat-related events. The HEAT questionnaire can be used to assess Housing and Indoor Environment, Emergency Preparedness, Awareness of Health Risks, and Temperature and Outdoor Environment.¹³ Based on information gathered, refer patients to needed resources and provide necessary education. Patients should be counseled on proper hydration (taking cool showers, wearing loose-fitting clothes, using sunscreen, and, if possible, avoiding being outside during the hottest times of the day); signs of heat-related illness and when to seek medical attention; and the HeatRisk tool, along with considerations related to indoor and outdoor air quality.^5-9,12

At home, patients can use blackout curtains or air conditioning, if they have them, to stay cool.¹² Patients without air conditioning should seek public cooling centers when temperatures are high; resources such as 211 can be used to find them in the local community.¹² Furthermore, fans should only be used when indoor temperatures are less than 90°F. Above that temperature, fans only move hot air around and can increase body temperature and dehydration.¹² Finally, discuss with patients taking certain medications about the potential for heat-drug interactions and collaborate with the members of their care team to create a medication plan for them.¹⁴ Teach patients about how to store medications properly and help them plan for medication storage when experiencing heat-related power outages.¹⁴Let patients know about the CDC’s patient-friendly resource, “Heat and Your Health,” which provides more information on the potential impact of heat on them, friends or family members, and their pets.¹² Pharmacists, along with other health care and public health professionals, should strive to raise awareness about the potential impacts of heat and heat-related environmental change on human health and incorporate practices to reduce patient risk.

Read the other installments:

Heat and Older Adults: What Pharmacists Need to Know

Heat and Medications: What Pharmacists Need to Know

REFERENCES

1. Centers for Disease Control and Prevention. Climate and health: Temperature extremes. March 2, 2024. Accessed April 27, 2026. https://www.cdc.gov/climate-health/php/effects/temperature-extremes.html

2. US Environmental Protection Agency. Climate change and extreme heat: What you can do to prepare. EPA; 2016. EPA 430-R-16-061.

3. Adams-Fuller T. Extreme heat is deadlier than hurricanes, floods, and tornados combined. Scientific American. July 1, 2023. Accessed April 27, 2026. https://www.scientificamerican.com/article/extreme-heat-is-deadlier-than-hurricanes-floods-and-tornadoes-combined/

4. Knowlton K. Climate change and health: Extreme heat. Natural Resources Defense Council. Accessed April 27, 2026. https://www.nrdc.org/resources/climate-change-and-health-extreme-heat#/map

5. National Academy of Medicine. Extreme heat as a climate health hazard. April 10, 2025. April 27, 2026. https://nam.edu/product/extreme-heat-climate-health-hazard/

6. Bell ML, Gasparrini A, Benjamin GC. Climate change, extreme heat, and health. N Engl J Med. 2024;390(19):1793-1801. doi:10.1056/NEJMra2210769

7. Ebi KL, Capon A, Berry P, et al. Hot weather and heat extremes: Health risks. Lancet. 2021;398(10301):698-708. doi:10.1016/S0140-6736(21)01208-3.

8. Khosla R, Jani A, Perera R. Health risks of extreme heat. BMJ. 2021;375:n2438. doi:10.1136/bmj.n2438

9. Centers for Disease Control and Prevention. Clinical overview of heat. September 18, 2025. Accessed April 27, 2026. https://www.cdc.gov/heat-health/hcp/clinical-overview/index.html

10. Readfearn G.‘Non-survivable’: Heatwaves are already breaching human limits, with worse to come, study finds. April 8, 2026. Accessed April 27, 2026. https://www.theguardian.com/environment/2026/apr/08/extreme-weather-heatwaves-breaching-human-survival-limits-study-finds

11. Jones, A.Understanding wet-bulb temperature: The risks of high wet-bulb temperatures explained. August 17, 2023. Accessed April 27, 2026. https://climatecheck.com/blog/understanding-wet-bulb-temperature-the-risks-of-high-wet-bulb-temperatures-explained

12. Centers for Disease Control and Prevention. About heat and your health. July 25, 2025. Accessed April 27, 2026. https://www.cdc.gov/heat-health/about/

13. Centers for Disease Control and Prevention. HEAT: A heat and health risk factor screening questionnaire. June 18, 2024. Accessed April 27, 2026. https://www.cdc.gov/heat-health/hcp/clinical-guidance/HEAT-screening-questionnaire.html

14. Centers for Disease Control and Prevention. Heat and medications: Guidance for clinicians. September 18, 2025. Accessed April 27, 2026. https://www.cdc.gov/heat-health/hcp/clinical-guidance/heat-and-medications-guidance-for-clinicians.html