Increased dehydration, reduced effectiveness, skin reactions… Some medications can worsen the health risks caused by high temperatures.
What are the risks?
Some medications can worsen the effects of high temperatures on the body: they can exacerbate dehydration (this is the case with diuretics, laxatives, some antiepileptics), increase body temperature (antidepressants, antipsychotics, antiparkinsonian drugs), or disrupt kidney function (anti-inflammatories and some antidiabetics), warns the French National Agency for the Safety of Medicines (ANSM).
Some neuroleptics, anti-migraine drugs and powerful painkillers (opiates) can also promote drops in blood pressure or cause drowsiness, with the risk of forgetting to drink enough, explains the ANSM.
During periods of intense heat, the body can lose up to several liters of water per day, and dehydration can also hinder the body's elimination of medications.
Sweating can alter the effect of medications in patch form, according to the ANSM (French National Agency for Medicines and Health Products Safety). For some medical devices, such as blood glucose self-monitoring strips for diabetics, their effectiveness may be reduced by heat.
Read also Everything you need to know (and do) in case of a heatwave
Sun and medication: a duo to watch out for
So-called photosensitizing drugs, such as certain treatments for acne, cancer, inflammation, infections, allergies, high cholesterol and some psychotropic drugs, can cause skin reactions when exposed to the sun: itching, redness or inflammation of the skin.
The ANSM (French National Agency for Medicines and Health Products Safety) recommends avoiding all sun exposure when taking medication that may interact with the sun. If exposure cannot be avoided, it recommends applying a high-protection sunscreen and covering up.
Special care is needed with gels containing ketoprofen, an anti-inflammatory used to treat tendonitis, back pain, osteoarthritis, or sprains. Even after stopping treatment, the treated area should continue to be covered for two weeks.
What impact on storage?
Many medications can be stored at room temperature, but if it is very hot, it is advisable to place them in the coolest room and transport them in an insulated container. These medications should not be exposed to direct sunlight.
Health authorities remind us that medications requiring refrigeration between 2 and 8°C, such as insulin and most vaccines, must be used promptly once removed from the refrigerator. For transport, refrigerated insulated packaging is necessary, for example, using ice packs to maintain the temperature.
However, the ANSM has not " There have been no reports of deaths or hospitalizations related to inadequate storage during the heatwave.e » in France.
Towards a better risk assessment
“ There are no specific clinical trials to develop improved heat resistance "medicines, but before being put on the market, all undergo stability studies to..." check if the active ingredient of the medication will degrade when exposed to high temperatures" explains Romain Barus of the regional pharmacovigilance center in Toulouse, in southwestern France, responsible for monitoring adverse drug effects during heat waves.
"It's mandatory and it's what will establish the rules for storing medicines." he adds.
To establish a cause-and-effect relationship, the Toulouse Regional Pharmacovigilance Centre will begin next year to look at which hospitalizations and possibly deaths are linked to an adverse effect that may have been exacerbated by the heatwave "based on data from the Health Insurance system and weather data."
This pharmaco-epidemiology project would allow us to " quantify the level of risk", in other words, to measure to what extent certain drugs increase the risk of heat-related complications, and in which patients.
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