Medications to treat various chronic diseases may hinder the body’s ability to lose heat and regulate its core temperature to optimal levels.

The loss of effective thermoregulation has implications for elderly people receiving treatment for illnesses like cancer, cardiovascular, Parkinson’s disease/dementia and diabetes, particularly during hot weather, according to a review by a team of scientists from various institutions in Singapore.

The group, led by Associate Professor Jason Lee from the Human Potential Translational Research Programme at the Yong Loo Lin School of Medicine, National University of Singapore (NUS Medicine), identified and reviewed relevant research papers using keyword searches on databases such as PubMed and Google Scholar.

These papers studied the associations and effects of medications on thermoregulation. The review findings were presented in a topical manner, focusing on medication classes used to treat commonly diagnosed chronic conditions (e.g., diabetes, cardiovascular disease, neurodegenerative disease, and cancer).

The findings show that medications used to treat common chronic conditions, like blood thinners, blood pressure drugs, Parkinson’s disease/Alzheimer’s medications, and some chemotherapy drugs, can make it harder for the human body to handle hot weather by reducing its ability to sweat or increase blood flow to the skin.

Lead author and second-year PhD candidate from the Human Potential Translational Research Programme Mr Jericho Wee said, “Rising global temperatures caused by climate change pose a significant health concern for clinical patients reliant on long-term medications and healthcare. Increasingly, we will continue to see more elderly patients, many who have multiple health conditions and are taking different types of medication concurrently to manage their chronic diseases, compounding the risk of heat-related illness and dehydration. Understanding how each medication impacts thermoregulation, in the face of warmer environments, is the crucial first step to predicting the possible health outcomes when multiple medications are taken concurrently.”

While previous reviews have highlighted the impacts of medications on heat, the scope of those reviews did not present the evidence in the context of the chronic diseases and ageing. The team’s narrative review presents the evidence in the context of high ambient temperatures and their impact on chronic disease sufferers who are on long-term and life-long medication.

Senior author Assoc Prof Jason Lee, who is also Director of the Heat Resilience and Performance Centre at NUS Medicine said, “This review emphasises the importance of studying the mechanisms of altered thermoregulation in individuals with diabetes and other cardiometabolic conditions to prevent heat-induced conditions. This is most relevant in Singapore and many other countries, where we have rapidly ageing populations and rising ambient temperatures. Pharmacological and thermal physiologists should focus transdisciplinary efforts on this area of research to refine and enhance safe medication prescription guidelines to preserve the health of people who need these medications, even in hot weather.”

The study was supported by the National Research Foundation, Prime Minister’s Office, Singapore under its Campus for Research Excellence and Technological Enterprise (CREATE) Programme.

The findings were published in Pharmacological Reviews, titled Effects of Medications on Heat Loss Capacity in Chronic Disease Patients: Health Implications Amidst Global Warming.