What Pharmacists Should Know for Heat Action Day

As the global community prepares for the fifth annual Heat Action Day on June 2, 2026, the focus shifted to the silent threat of indoor heat. Although many associate extreme heat with outdoor activities, this year’s theme highlights the critical health risks faced by individuals within their own homes, schools, and care facilities.^1,2

For pharmacists, this day serves as a vital call to action, as they are uniquely positioned to manage the complex intersection of extreme temperatures and pharmaceutical care. With climate change driving longer and more intense heatwaves, the role of the medication expert has never been more essential in protecting vulnerable populations from heat-related illnesses.³

Extreme heat is characterized by abnormally high temperatures and humidity lasting at least 2 to 3 days, which can severely impact the efficacy, safety, and accessibility of various medications. Pharmacists must be aware that heatwaves do more than just cause discomfort, as they can exacerbate chronic conditions such as diabetes, cardiovascular disease, and renal impairment. Furthermore, certain populations, including infants, pregnant women, and older adults, face a disproportionately high risk of dehydration, hyperthermia, and heat stroke. These risks are often compounded for those living in urban "heat islands" or energy-poor households where indoor cooling is unavailable or unaffordable.^1-3

A primary clinical concern for pharmacists is the physiological impact of specific drug classes on the body’s ability to regulate its temperature. The body relies on sweating, regulated by the neurotransmitter acetylcholine, to cool itself. However, medications with anticholinergic activity—such as many antipsychotics, antihistamines, and antidepressants—can impede this process.³

Additionally, selective serotonin reuptake inhibitors can impair the thermoregulatory function of the hypothalamus, and stimulants used for attention deficit/hyperactivity disorder and certain thyroid hormones can increase cellular metabolism and core body temperature. Medications like angiotensin-converting enzyme inhibitors and glucagon-like peptide-1 agonists may also decrease a patient's thirst, leading to dangerous levels of dehydration.³

The threat extends beyond physiological response to the very stability of the medications themselves. High temperatures can degrade various dosage forms, including transdermal patches and inhalers, and can impact the delivery of drugs via elastomeric infusion pumps used in home care. Maintaining the cold chain for insulin, vaccines, and blood products becomes a significant challenge during extreme heat events, particularly if power outages occur. Pharmacists are also tasked with monitoring the pharmacokinetics of drugs with a narrow therapeutic index, such as lithium or carbamazepine, as heat-induced dehydration can alter renal function and lead to toxic blood levels.³

To mitigate these risks, CDC suggests that pharmacists employ the HEAT questionnaire—addressing Housing, Emergency preparedness, Awareness, and Temperature—to evaluate a patient's risk profile. This includes asking patients if they have a plan for refrigerated medications during power outages and if they understand how their specific prescriptions might complicate their health in hot weather. Pharmacists should also provide targeted counseling on photosensitivity for patients taking certain antibiotics or nonsteroidal anti-inflammatory drugs (NSAIDs), recommending broad-spectrum sunscreen and protective clothing.³

As trusted community healthcare providers, pharmacists are encouraged to participate in Heat Action Day by sharing life-saving tips and collaborating with the broader medical team to adjust medication schedules during high-risk periods. By educating patients on how to store medications away from hot environments like cars and identifying those at risk due to polypharmacy, pharmacists can prevent avoidable tragedies. In a warming world, the proactive involvement of pharmacists ensures that life-saving medications remain a source of healing rather than a source of heat-related harm.^1-3

READ MORE: Heat and Medications: What Pharmacists Need to Know

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REFERENCES

1. International Federation of Red Cross and Red Crescent Societies. Heat Action Day. 2026. Accessed June 1, 2026. https://www.ifrc.org/get-involved/campaign-us/heat-action-day

2. Prepare Center. Heat Action Day. 2026. Accessed June 1, 2026. https://preparecenter.org/initiative/heat-action-day/

3. D’Souza MS, DiPietro Mager N. Heat and Medications: What Pharmacists Need to Know. Drug Topics. May 20, 2026. Accessed June 1, 2026. https://www.drugtopics.com/view/heat-and-medications-what-pharmacists-need-to-know