Heatwave and Medications: Which Treatments Become Risky in the Heat and How to Store Them

High temperatures can affect both the efficacy of certain medications and the body's ability to cope with extreme heat. The Centers for Disease Control and Prevention (CDC) in the US warns that certain treatments increase the risk of dehydration, overheating, and electrolyte imbalances, whilst exposing medications to excessive heat can reduce their effectiveness.

Specialists explain that some treatments interfere with the body's natural temperature-regulation mechanisms, reducing its ability to cool down, promoting dehydration, or altering its response to extreme temperatures, according to information published by Click!.

Elderly people and those with chronic conditions — cardiovascular disease, diabetes, or kidney disease — are among those most at risk of complications during heatwaves.

Medications that may increase the risk of complications during a heatwave

According to the CDC, several categories of treatments require extra caution when temperatures are high:

• Diuretics — promote fluid loss and can lead to dehydration and electrolyte imbalances.
• Antihypertensive medications, including angiotensin-converting enzyme (ACE) inhibitors and beta-blockers — can reduce the body's tolerance to heat.
• Medications with anticholinergic effects — reduce perspiration, hampering the body's natural cooling process.
• Certain antidepressants and antipsychotics — can affect body temperature regulation and the sensation of thirst.
• Stimulants used in the treatment of ADHD — can cause an increase in the body's core temperature.

Specialists advise patients not to discontinue their treatment on their own initiative, but rather to consult their doctor if they experience dizziness, signs of dehydration, or marked heat intolerance.

Antibiotics and antifungals that increase sensitivity to sunlight

In addition to their effects on temperature regulation, some medications increase the skin's sensitivity to solar radiation. These include antifungals such as flucytosine, griseofulvin, and voriconazole, as well as antibiotics such as metronidazole, tetracyclines, and fluoroquinolones. Combining these treatments with sun exposure can cause skin reactions similar to sunburn.

How to store medications correctly in hot weather

High temperatures affect not only the body but also the chemical stability of medications, reducing their effectiveness. Most products should be stored below 25°C, ideally between 15 and 25°C. Those requiring refrigeration must be kept between 2 and 8°C, as indicated on the packaging.

Specialists warn that inhalers should not be left in cars or other overheated spaces, as they can be damaged or may explode under conditions of extreme heat.

Insulin and GLP-1 medications — sensitive to heat

Insulin is a protein-based medication, and exposure to high temperatures can alter its structure and reduce its effectiveness. Manufacturers recommend storing unopened vials or pens in the refrigerator; those already in use may be kept at room temperature only for the period indicated in the package leaflet.

The same rules apply to GLP-1 class medications, such as Wegovy and Mounjaro, used in the treatment of type 2 diabetes and for weight management. These must be kept refrigerated before use, and after opening may be stored at temperatures below 30°C, in accordance with manufacturers' instructions.

Medical devices — equally vulnerable to heat

It is not only medications that are affected by high temperatures. Studies show that exposing blood glucose meters and test strips to temperatures of approximately 42°C under conditions of high humidity can produce falsely elevated blood glucose readings.

Specialists recommend storing medications and medical devices strictly in accordance with the instructions on the packaging, and avoiding exposing them to sunlight or overheated spaces, in order to preserve their effectiveness and safety in use.