Certain medications, some of them prescription, others that can even be bought without a prescription from pharmacies, can become dangerous on hot days.
The CDC (Centers for Disease Control and Prevention), the main US federal public health agency, warns that certain medications and excessive heat combined can lead to potentially severe side effects. For this reason, the CDC has published recommendations for doctors and patients about how heat may interact with some treatments. Specialists point out that people undergoing chronic treatments should talk to their doctor before hot periods about any necessary measures – for example, how to hydrate, what symptoms to watch for and whether more careful monitoring of treatment is needed.
Medicines that become dangerous when it’s hot
Commonly prescribed medications that increase the risk of side effects during hot weather include: diuretics, anticholinergic agents (drugs that block the action of acetylcholine, a neurotransmitter involved in functions such as sweating, salivation, digestion, bladder contraction, and heart rate regulation), and some psychotropic medications.
Over-the-counter medications can also interact with heat.
“Certain drug combinations, such as an angiotensin-converting enzyme (ACE) inhibitor or an angiotensin II receptor blocker (ARB) with a diuretic, can significantly increase the risk of injury from heat exposure,” warn CDC experts.
ACE (angiotensin converting enzyme) is an enzyme involved in blood pressure regulation, ACE inhibitors are medicines used to treat high blood pressure and heart failure (eg: Enalapril, Ramipril). Angiotensin II receptor blockers (ARBs) are another class of drugs for hypertension and heart failure that work differently than ACE inhibitors but have similar effects on blood pressure (eg: Losartan, Valsartan).
Angiotensin-neprilysin receptor inhibitors (ANRIs), which are newer drugs used primarily to treat heart failure, may carry the same risk, the CDC also warns.
For children and adolescents, medications that may increase the risk of heat illness include nonselective antihistamines (eg, diphenhydramine), stimulants such as methylphenidate for attention-deficit/hyperactivity disorder (ADHD), tricyclic antidepressants, selective serotonin reuptake inhibitors (SSRIs), and diuretics.
What effects can they cause?
In the context of heatwaves, these drugs can increase the risk of heat-related illnesses because they can promote dehydration, alter blood pressure regulation, reduce the body’s ability to eliminate heat, or affect the mechanisms by which the body maintains its normal temperature. The risk is even greater when certain classes of drugs are given in combination.
According to the CDC, medications can affect the body, during hot periods, as follows:
– reduced feeling of thirst (this is the case with drugs such as: diuretics, ACE inhibitors, ARBs and ARNIs);
– interference with central thermoregulation (eg antipsychotics, anticholinergics, stimulants);
– impaired sweating and therefore impaired cooling (increased with selective serotonin reuptake inhibitors (SSRIs), serotonin and norepinephrine reuptake inhibitors (SNRIs), and decreased with tricyclic antidepressants (TCAs), typical and atypical antipsychotics, anticholinergic agents);
– volume depletion (decrease in the volume of circulating blood, especially through the loss of the liquid component – plasma, i.e. a form of dehydration that affects blood circulation); hypotension or reduced cardiac output, which can lead to dizziness, fainting and falls; in conditions of dehydration, the decrease in blood flow to the kidneys, together with the administration of drugs with nephrotoxic potential, can favor the occurrence of acute kidney damage (non-steroidal anti-inflammatory drugs (NSAIDs) – for example Ibuprofen, Naproxen, Diclofenac; diuretics; beta-blockers – for example Metoprolol, Bisoprolol; tricyclic antidepressants; laxatives);
European patients are paying the true price of government intervention in drug pricing
– the blood vessels on the surface of the skin do not dilate sufficiently, and the body can no longer effectively remove heat (for example – aspirin, beta-blockers and clopidogrel);
– drug toxicity caused by the reduced clearance (the speed with which the body, mainly the kidneys and liver, removes a drug) of drugs in dehydrated people, especially for drugs with a narrow therapeutic index (for example – carbamazepine and lithium);
– electrolyte imbalance (change in the concentration of essential minerals in the body, such as sodium, potassium, calcium and magnesium, which are necessary for the normal functioning of the heart, muscles and nerves) – which can be generated, for example, by: diuretics, antacids, laxatives, lithium and trimethoprim-sulfamethoxazole, etc.)
– Drowsiness, dizziness or difficulty concentrating which may decrease the feeling of thirst (which may be caused by, for example, opiates, benzodiazepines, typical and atypical antipsychotic drugs, antidepressants, anticonvulsants).
“Additionally, exposure to heat can damage medication delivery devices or degrade medications. Inhalers, for example, can explode in hot environments, such as car trunks on hot days. EpiPens can malfunction or release less epinephrine when exposed to heat. Insulin, which must be refrigerated, can become less effective if left in heat for long periods of time.” the CDC also warns.
What to do if you take a medicine from the list
Some medications can also increase the skin’s sensitivity to the sun. This is the case with antifungal drugs such as flucytosine, griseofulvin and voriconazole and antibiotics such as metronidazole, tetracyclines and fluoroquinolones. These can increase sensitivity to the sun and lead to a sunburn-like rash. Avoiding sun exposure, wearing protective clothing and hats, and a broad-spectrum sunscreen that filters UVA and UVB rays with an SPF of 30 or higher is recommended for patients taking these medications.
If you have drugs from the classes mentioned above in your treatment regimen, first of all pay extra attention to heat exposure. Avoid exposure as much as possible to prevent adverse effects. Talk to your doctor if you are taking any of the classes mentioned above. Depending on your health, he can decide whether closer monitoring or, in certain situations, adjustment of the treatment is necessary. But never change the treatment on your own initiative.
Do not, under any circumstances, stop taking the treatment without the doctor having decided to do so and without having prescribed other medicines.
Any change in the dose or medication administration schedule must be individualized. The decision will depend on the class of drug and will be made by considering the risks and benefits.
Why ibuprofen is recommended instead of paracetamol for menstrual pain. The difference between the two drugs
Talk to your doctor and ask about signs and symptoms that might indicate an interaction between heat and the medications you’re taking. It should guide you when to seek medical attention, which symptoms are an emergency, and what to do in an emergency.
Also, be very careful how you store your medicines during hot weather. Insulin must be stored according to the instructions in the leaflet. Unstarted insulin supplies are usually kept in a refrigerator (2-8°C), and the pen or vial in use can be kept, depending on the type of insulin, at room temperature for the period indicated by the manufacturer. Prolonged exposure to high temperatures may reduce its effectiveness.
Never leave medications in your car or other places that can get excessively hot. Always observe the storage conditions in the leaflet. Most medications are stored at room temperature, away from excessive heat, direct sunlight, and moisture, but some products, such as insulin or certain biologics, require refrigeration.
Be very careful with pressurized devices such as inhalers. Very high temperatures can affect their operation and, in rare cases, cause the container to explode.
If your doctor has adjusted the treatment regimen and made other recommendations, also determine with him when a new analysis and adjustment of the medication will be needed.
