Author : Maria José Rei, pharmacist at Hospital da Luz Lisboa In the warmer seasons, high temperatures are associated with harmfull effects for health, increasing the cases of illness and mortality. Thus, particularly during a heatwave, which is a prolonged period with abnormally high maximum and minimum daily temperatures for the season, special care must be taken . Anyone can be affected by hot weather .There are, however, more vulnerable groups: The elderly; Younger children; Pregnant women; People with chronic illnesses. Among these, the elderly are a particularly vulnerable group: Their physiological ability to regulate temperature – and therefore to adapt to increased environmental temperature – is reduced; They are more likely to have chronic illnesses and take multiple medications; Some medications can interfere with the thermoregulation mechanism and/or potentiate some of the effects of heat. Medicines that may potentiate heat-related problems In most cases, when taken as directed, the drugs themselves pose no risk. They can, however, aggravate hot weather-related problems. Several mechanisms are involved like: Alteration of central thermoregulation; Decreased sweating; Dehydration; Sedation and cognitive impairment; Kidney function changes; Hypotension and slow heart rate, which can also increase the risk of fainting and falls. Examples of medicines that can potentiate the effects of heat If you take any of the medications listed below, during hot weather be more aware of the effects of heat. If in doubt, seek medical attention. Medicines used in cardiology : Diuretics can potentiate dehydration. Medicines to control blood pressure and angina pectoris can potentiate hypotension. Some medications used to control heart rhythm may be more toxic in case of dehydration. Medicines used in psychiatry : Antipsychotics and antidepressants can interfere with central thermoregulation and potentiate hypotension and cognitive impairment. Lithium can potentiate sedation and cognitive changes. Anticonvulsant medications can cause hypotension and sedation. Topiramate, in particular, has been linked to adverse events during hotwaves by decreasing sweating. Some drugs used to treat Parkinson disease and urinary incontinence can make sweating more difficult by affecting body temperature regulation. Some immunosuppressants and anti-inflammatories can affect kidney function in case of dehydration. Anxiolytics and opioids may have their sedative and cognitive-altering effects enhanced by heat. Recommendations to mitigate risks Do not stop taking your medication without talking to your doctor, as abruptly stopping your medication or losing control of your medical condition can have serious complications. Consult your doctor if your health condition requires regular follow-up, especially if several months have passed since your last consultation or if you notice changes in your usual condition. If you take medication to control your blood pressure, monitor it more frequently. If you take diuretics, watch out for signs of dehydration, such as thirst, dry mouth, dizziness, irritability, or darker and/or less frequent urinate. Do not take medicines, even over-the-counter ones, that have not been prescribed by your doctor or advised by a pharmacist who is aware of your health condition and usual therapy. Avoid alcohol consumption during hot weather, as alcohol increases the risk of dehydration. Follow all the protection recommendations during hot weather , not forgetting those that refer to nutrition and hydration . Precautions for storing and transporting medicines Check the package leaflet for your medications for storage requirements. Medicines that need to be stored below 25°C to 30°C can be stored in their usual place. High temperatures for a few days do not harm these drugs as long as they are protected from direct light and heat. During transport, if prolonged exposure to high temperatures is foreseeable (above 25°C to 30°C), they may be transported in non-refrigerated isothermal bags, as a precautionary measure. Medicines that must be kept at a temperature between +2°C and +8°C are usually kept in your fridge and therefore a heatwave will not affect their stability. However, once removed from the fridge, avoid leaving them out for a long time. They must be transported in a refrigerated isothermal bag, which contains ice accumulators, taking care to check that they do not come into direct contact with them so as not to freeze. For any medicine, even when well-packaged, it is important to make sure that it is not exposed for a long time to the high temperatures that are often reached, for example, inside cars left in the sun. Some drug formulations, such as capsules, suppositories and creams, are quite sensitive to high temperatures. You must not use any medicine in which you detect a change in appearance after exposure to heat, regardless of the expiry date. Source: Ana Paula Mendes. Ondas de calor: riscos associados aos medicamentos . Centro de Informação do Medicamento, 2023. Instituto Nacional de Emergência Médica. O que fazer em caso de desidratação . Joana Quintal, Autora Simon. Viajar com medicamentos . Centro de Informação do Medicamento, 2016. The content published in the Health Guide is intended for the general public and is provided for informational and educational purposes only. It does not replace individual medical assessment, diagnosis, or personalized clinical advice from a qualified healthcare professional. The content is produced or reviewed by physicians and other healthcare professionals at Hospital da Luz and is based on the knowledge available at the time of publication or the most recent update, as indicated at the beginning of each item.
