When the thermometer rises, everyone suffers a little. But for people who take certain treatments long-term, extreme heat increases the risk of discomfort, dehydration or heat stroke. The body relies on sweating, blood flow to the skin, and water balance to cool itself, and many medications disrupt these mechanisms.
This is what pharmacist Dipa Kamdar points out in an article: five large families of drugs
currents clearly complicate life in the event of a heatwave.
These are the antidepressants (SSRIs and tricyclics), antipsychotics, certain heart and blood pressure treatments, stimulants for ADHD andinsulin. According to Health Insurance, sweating provides more than three quarters of temperature regulation, which explains why these treatments can be problematic.
How these medications disrupt body heat
SSRI and tricyclic antidepressants alter levels of serotonin and norepinephrine in the brain. Tricyclics can also block acetylcholine, a key sweating messenger, which sometimes reduces sweating. Conversely, increased norepinephrine can cause profuse sweating, and up to 14% of people taking antidepressants report this type of side effect. SSRIs can also interfere with the hypothalamus, the temperature “control tower,” which normally tells the sweat glands to turn on.
Antipsychotics, used against schizophrenia or bipolar disorders, block dopamine and also influence serotonin. Dipa Kamdar explains that this disrupts the hypothalamus’ ability to sense and correct temperature variations.
A person may not feel warm or thirsty, even though their body is becoming dehydrated.
These molecules also have anticholinergic effects, which further slow down sweating. For their part, beta-blockers reduce the frequency and strength of the heartbeat, and therefore blood flow to the skin. While diuretics and antihypertensives such as ramipril or losartan promote water loss and sometimes reduce the feeling of thirst.
ADHD stimulants and insulin: an often overlooked risk
Amphetamine-type stimulants prescribed in
ADHD act on dopamine and norepinephrine. They increase metabolism, internal temperature and modify sweating. In the heat, the body heats up more quickly, especially during physical exertion, with a risk of dehydration or heat stroke.
As these medications reduce the feeling of fatigue, some people strain without realizing it. Recent work suggests that, well hydrated, treated patients are not necessarily more exposed than expected, but the authors call for larger studies.
For theinsulinthe problem is twofold. Heat dilates blood vessels, which accelerates its absorption at the injection site and can make hypoglycemia more frequent and more sudden. Dipa Kamdar recalls that this causes dizziness, tremors, sweating, irritability, even loss of consciousness or convulsions.
At the same time, heat can degrade poorly stored insulin: it becomes cloudy or changes color and loses effectiveness. The symptoms of hypoglycemia are easily confused with those of a simple “heat stroke”, which complicates monitoring.
Medications and extreme heat: the right reflexes to adopt
Health Insurance and the ANSM insist on one point: you should never stop or change your treatment alone, even during a heatwave. However, it is useful to speak with your doctor or pharmacist in advance if you are taking one of these medications, especially in cases of advanced age, chronic illness or multiple treatments.
Drinking regularly (unless otherwise medically advised), staying in cool places, avoiding exercise during the hottest hours and watching for signs of dehydration or confusion are some of the basics.
Dipa Kamdar also advises checking the conservation information on each box. Many specialties must remain at 25 to 30°C, and insulin between 2 and 8°C before opening. It is best never to leave your treatments in a closed car or on a windowsill in direct sunlight.
Adrenaline inhalers and auto-injector pens can also become less effective if they get too hot. Anticipating heat episodes with healthcare professionals allows you to adapt your daily life, while keeping your treatment and your body safe.