Scientists warn. Some drugs may cause dangerous side effects in hot weather
Usually our body reacts to the heat of dilating blood vessels and sweat secretion. Evaporation causes the cooling effect, which maintains a constant body temperature. Some drugs, however, disturb these thermoregulatory processes, and thus the body's ability to cool down by sweating at high temperatures.
In the worst case, this can be dangerous. Here are medicines that can cause dangerous side effects in the heat.
Are you afraid that your drugs can be a problem at high temperatures? Consult it with a specialist. – Reduction of dose or interruption of taking medication should take place only after consulting a doctor – says cardiologist Christopher Schneweis, who runs a cardiology clinic in Cologne.
People taking certain medications can be exposed to life threatening in hot weather, often not realizing it. This problem especially applies to the elderly.
The results of several studies confirm the impact of some drugs on the health risk associated with heat. In 2020, as part of a large -scale study, the relationship between heat waves, specific drugs and hospitalizations caused by heat among older patients suffering from chronic diseases was examined.
The results have shown that diuretic drugs, prescribed mainly in the case of heart failure, but also in the treatment of hypertension, increase the risk of hospitalization if they are taken in the heat. – Especially in older patients taking these drugs, there may be more fluid and electrolyte loss at very high temperatures, because they often do not drink enough fluid in hot weather – confirms the cardiologist Christopher Schnewewei.
The study also showed that in addition to diuretics, problems during hot weather may also cause antipsychotics and so -called anticholinergic drugs. Anticholinergic drugs inhibit the effects of acetylcholine neurotransmitter and are used to treat various diseases such as asthma, irritable bowel syndrome, Parkinson's disease, bladder hyperactivity, nausea, vomiting and dizziness.
Anticholinergic drugs also include many psychotropic, antidepressant drugs and many benzodiazepines (sleeping pills).
Increased risk of heat stroke
The most comprehensive review of literature on this subject was published in 2024 in the scientific journal “The Lancet” and confirmed that Some drugs may increase the risk of heat stroke (hyperthermia). Thermal stroke can occur when the mechanisms of heat adjustment in the body are overloaded. As a result, the body temperature increases very rapidly, usually above 40 degrees Celsius.
A moderate, short -term increase in body temperature is usually not a problem, but if the body is unable to remove heat, it accumulates, as a result of which the body temperature increases to 40 degrees and more.
– First, coagulation and blood circulation disorders occur. Then the blood thickens. Small clots clog small blood vessels. Kidneys, but also the liver and heart are not able to function properly – explains the neurologist prof. Frank Erbguth. In the worst case, this threatens multi -organ failure.
The thermometer shows the heat in the city (illustrative photos)
Sudden fatigue, headaches, balance disorders, and in the case of deterioration: nausea, vomiting and loss of consciousness. If someone has the described symptoms of heat stroke, you should immediately call an ambulance. The heat stroke can lead to a coma, and in the worst case it ends with death.
The impact of 27 popular drugs on body temperature in the heat
Scientists of this study from “The Lancet” analyzed 35 studies involving a total of 353 people, almost exclusively young men. They compared the impact of 27 drugs on prescription and without a prescription available to body temperature during exposure to heat while playing sports.
They examined beta-blockers, adrenaline, drugs against Parkinson's disease, antidepressants, antipsychotics, antiallergic drugs, blood vessels, diuretic tablets and agents against nausea. The World Health Organization (WHO) classifies these medicines as potentially harmful in the case of overheating.
The study showed that drug temperature with strong anticholinergic effects has a particularly strong effect on body temperature. For example, atropine – one of the many active substances of this group of drugs – at an ambient temperature of 30 degrees Celsius caused a 0.42 degree increase in body temperature and an increase in skin temperature by 2.9 degrees. People affected by this phenomenon were not able to excrete sweat – the body cooling function was disturbed.
Atropine is used in emergency medicine in the event of a slowdown in heart rate, it can be administered before anesthesia to accelerate heart rate, and in ophthalmology is used to expand the pupils.
Adrenaline, drugs against Parkinson's disease, beta-blockers
In addition to atropine, some other drugs also caused a significant increase in the inner temperature of the body during heat stress and reduced sweat production: among others adrenaline and drugs against Parkinson's disease, such as bromocriptin, levodopa and karbidopa.
Selective beta-blockers, e.g. propranolol, cause an increase in the inner temperature of the body while lowering the skin temperature. They did not affect the pace of sweating.
The analysis showed that the following drugs had no or only had a very little impact on the internal temperature of the body and sweating:
- antidepressants, including bupropion, citalopram, paroxetine and reboxetin,
- Haloperidol antipsychotic drug,
- Meprobamat sedative,
- antihistamine drug fxaphenadin,
- Blood vessels such as pryosin, clonidine and nifedipine,
- and nausea drugs, among others Ondansetron and Granisetron.
Scientists have not demonstrated a significant effect of diuretic drugs (hypertension tablets): acetazolmide, hydrochlorotiazide and furosemide.
Although this study is solid in terms of methodological, it is not important for the elderly and chronically patients who are exposed to heat mainly passively (in the study, the exposure to heat was studied while playing sports).
Scientists also did not examine the use of many drugs that are common among the elderly. In addition, the study at which the internal temperature and sweating pace were measured only included physiological effects, and not any changes in behavior caused by taking medication (e.g. reduction of the amount of liquids drunk or limiting the avoidance of heat).
Health institutions warn against using these drugs in the heat
The World Health Organization warns that the elderly is a group particularly vulnerable to the heat – especially if seniors are taking drugs that inhibit sweating or affecting circulation. As a particularly vulnerable group, women who “suffer from chronic diseases are mentioned, are socially insulated and live on the highest floors.” WHO lists specific groups of drugs that can cause dangerous side effects in the heat:
- anticholinergic drugs,
- antipsychotics,
- antihistamines,
- Parkinsonism drugs,
- antidepressants,
- Anthylakes and muscle relaxing drugs,
- anti-adrenergic drugs and beta-blockers,
- sympathomimetics,
- antihypertensive and diuretic drugs,
- Antilepsy.
In addition to thermoregulation, a group of these drugs can dangerously affect the body's water management -increase the risk of dehydration and cardiovascular metabolism disorders. Drugs lowering blood pressure, such as beta-blockers, are considered dangerous in the heat, because they make it difficult to give heat to the body, delay sweating and cause cardiovascular instability by lowering blood pressure too much.
