High temperatures: A rising problem for pharmacovigilance

According to UN Weather report, there were approximately 489,000 heat-related deaths annually between 2000 and 2019, with 36 per cent occurring in Europe and 45 per cent in Asia.

With global warming making extreme weather phenomena more and more common, heat waves have also begun to break records. While some may welcome the seemingly sunnier summers, for millions this weather anomaly entails being hit hard physically and economically. Rising temperatures bring with them droughts, that cause issues in agriculture and food chains, threaten access to clean water, and cause wildfires that lower air quality. As heat waves intensify and lengthen, they are spreading globally. Urban areas are particularly vulnerable, due to them overheating faster than rural areas, causing the so-called 'urban heath island effect'. With this in mind, are pharmaceuticals at risk too?

Drug and heat interactions

Ambient temperature, simply meaning the temperature of the surrounding environment, can have different effects on the chemical compounds of drugs. Depending on the drug, higher temperatures may:

• Degrade active ingredients, breaking them down and potentially rendering the medication ineffective or even harmful. 

• Increase a drug's potency, raising the risk of overdose.  

• Damage medical devices that deliver the drugs, such as inhalers or EpiPens.  

Some common temperature-sensitive medications include antibiotics, vaccines, insulin, birth control pills, epinephrine, inhaled medications like Albuterol inhalers, nasal sprays and various ear, eye and oral drops. There are, however, many more. Depending on the medication, proper storage may require a controlled room temperature, or, in some cases, refrigeration to ensure safety. 

Medications that lose potency won't properly treat infections, chronic illnesses or work as a preventative method for these conditions. In some cases, this might lead to lifesaving treatments being low in quality or completely insufficient.  

Some medications may also make you more susceptible to sun and increase heat sensitivity by changing the natural processes of the body's cooling mechanisms. For example, different drugs can interfere with thermoregulation, fluid balance, vasodilation as well as impair sweating, reduce thirst sensation or increase photosensitivity causing a heightened risk for sunburns. In addition, some medications can increase heart rate and metabolism, which further adds to heat stress.

Medications for mental health can produce similar effects. Some antidepressants and antipsychotics can have an effect on the hypothalamus, a crucial structure in the brain that regulates body temperature, as well as sweat glands and thirst signals.

If the body is not able to cool itself properly, the risks range from dehydration, electrolyte imbalance, exhaustion and confusion to loss of consciousness, seizures, strokes and heart attacks. Overheating, a condition where the body's internal temperature becomes too high, is also known as hyperthermia.

Climate change and the pharmaceutical supply chain 

Securing much needed medications for everyone globally requires a well-designed and crisis proof network between production, delivery and end customer. This includes proper storage conditions, transportation and distribution during extreme weather conditions.

Environmental disruptions, like wildfires and droughts, limit access to pharmaceuticals for many and cause a wide range of health damages. Diminished water supply and dry soil may also impact the production of natural materials used in medicine production. Communities in areas with a limited access to cold chain or electricity due to isolation, instability or cuts during extreme weather face greatest risks, putting strain on their healthcare systems. Such conditions lead to safety issues and compromise the effectiveness and quality of medications and further widen the gap in access to essential drugs.

In addition to production and delivery, climate change also creates shifts in demand by changing disease patterns. Infectious diseases that are vector-borne, meaning transmitted by vectors like mosquitoes and ticks, like malaria and dengue thrive in higher temperatures due to the changes in insect activity. Chronic conditions, like cardiovascular diseases, also tend to worsen during these periods due to extra strain on the heart. Heat waves have also been associated with negative mental health, due to disruptions in neurotransmitters, physiological stress and worsened cognitive function. When it's really hot, individuals can become irritated, angry and even more depressed.

Managing medications safely

Despite these bleak developments in pharmacovigilance, an area in pharmaceutics focusing on drug safety, there are measures we can take to reduce potential risks and adapt.

On a personal level, patients can protect their medications by following safe storage practices that are usually described on packaging or as instructed by a health care professional. Usually this means keeping them out of direct sunlight, avoiding high-heat environments like parked cars and being mindful of dosage and any unusual symptoms that might arise after usage. Often the dosage or frequency can be adjusted together with a professional and a plan can be made in advance for hot weather.

On a larger scale, health systems and pharmaceutical providers have a chance to review how drugs are designed, distributed and stored. It is crucial to evolve beyond just monitoring adverse drug reactions, but take into account the rapidly changing environment of the patients. Heat-stable formulations, strengthened cold chains and support for better infrastructure capable of withstanding climate change are critical in further development.

Sources:

1. The potential impact of climate change on medication access and quality deserves far more attention, W. Kaplan, D.Hammer & K. Shioda (June 2025)

2. Heat and Medications - Guidance for Clinicians, CDC (June 2024)

3. How heat affects the mind, American Psychological Association (June 2024)

4. Some medications can increase risk of heat-related illness, UCLA Health (July 2024)

5. Deciphering the impact of heat wave in the global surge of infectious diseases, M.Meher, et al. (September 2025)

6. Extreme heat is breaking records worldwide: UN weather agency, United Nations (August 2025)

Assessed and Endorsed by the MedReport Medical Review Board