Effects of medications on heat loss capacity in chronic disease patients: health implications amidst global warming

Pharmacological agents used to treat or manage diseases can modify the level of heat strain experienced by chronically ill and elderly patients via different mechanistic pathways. Human thermoregulation is a crucial homeostatic process that maintains body temperature within a narrow range during heat stress through dry (i.e., increasing skin blood flow) and evaporative (i.e., sweating) heat loss, as well as active inhibition of thermogenesis, which is crucial to avoid overheating. Medications can independently and synergistically interact with ageing and chronic disease to alter homeostatic responses to rising body temperature during heat stress. This review focuses on the physiological changes, with specific emphasis on thermolytic processes, associated with medication use during heat stress. The review begins by providing readers with a background of the global chronic disease burden. Human thermoregulation and ageing effects are then summarised to give an understanding of the unique physiological changes faced by older adults. The effects of common chronic diseases on temperature regulation are outlined in the main sections. Physiological impacts of common medications used to treat these diseases are reviewed in detail, with emphasis on the mechanisms by which these medications alter thermolysis during heat stress. The review concludes by providing perspectives on the need to understand the effects of medication use in hot environments, as well as a summary table of all clinical considerations and research needs of the medications included in this review. Long-term medications modulate thermoregulatory function, resulting in excess physiological strain and predisposing patients to adverse health outcomes during prolonged exposures to extreme heat during rest and physical work (e.g., exercise). Understanding the medication-specific mechanisms of altered thermoregulation has importance to both clinical and research fraternities, paving the way for work towards refining current medication prescription recommendations and formulating mitigation strategies for adverse drug effects in the heat in chronically ill patients.