A man pours water atop his head outside the Emergency Aid Coalition during a heat wave in Houston, Texas, U.S., August 25, 2023.
| Photo Credit: Reuters
The world just experienced the hottest day on record and prolonged heat waves have become more common due to climate change, conditions that can alter medications and their effects on patients taking them.
How does heat alter the effects and quality of medicines?
Medications for common conditions can increase patients’ sensitivity to heat by impairing the body’s response to high temperatures, including the ability to sweat and the rate of blood flow.
When sweat evaporates, it removes heat from the skin. Not being able to sweat can cause the body to rapidly accumulate deadly levels of heat.
Heat waves also increase the risk of deterioration for nearly all medications, whether capsules, sprays, tablets, syrups, or some other form, if they are not kept within a certain temperature range.
The heat-related effects of medications can vary based on individual health status, dosage and environmental conditions.
Patients should consult their physicians about potentially adjusting doses or scheduling in hot weather, and they should keep cool by staying hydrated, carrying fans, and seeking shade or air conditioning, experts say.
What medications increase sensitivity to heat?
Blood pressure and heart failure medications: Angiotensin converting enzyme (ACE) inhibitors suppress thirst, making it harder to know when to drink more water and increasing the risk of dehydration. Calcium channel blockers can cause mineral imbalances, making it harder for the body to regulate its temperature, while beta blockers can make it harder to sweat and keep the body cool. Diuretics, or water pills, can also cause dehydration and mineral imbalances.
Allergy medications: Some over-the-counter antihistamines reduce sweating and can impair temperature regulation.
Psychiatric medications: Certain antipsychotic medications limit patients’ ability to sweat. Some antidepressants have the opposite effect, increasing sweating and repressing thirst. Stimulants such as amphetamines and other drugs used to treat attention deficit hyperactivity disorder may interact with the central nervous system to raise body temperature.
Thyroid medications: Thyroid hormone pills also can raise body temperature, impair temperature regulation and cause excessive sweating.
What is a safe temperature range for storing medicines?
Extreme heat (and extreme cold) can significantly alter the effectiveness of prescription and over-the-counter drugs.
Some medications can tolerate temperatures up to 30 degrees C. However, in general, they should be stored at 15-77 degrees C in a cool, dry place, away from sunlight. Temperature storage guidelines for specific drugs can be found on manufacturers’ websites.
It’s hard to predict the extent to which a medication will degrade in extreme temperatures because each drug is different, said Amy Bachyrycz, a pharmacy faculty member at the University of New Mexico in Albuquerque in the U.S.
In general, medicines should not be left in hot cars or for hours in hot mail boxes if they have been ordered online.
