On a hot day, you may feel different, uneasy, or a bit “off” in ways that are easy to dismiss but difficult to ignore. Your hands and feet might swell up, you may get headaches more readily, and your energy may seem to drain much faster than usual. For people who live with chronic pain, migraine, or inflammatory conditions, these feelings can be particularly pronounced.
These experiences do, however, have a reasonable explanation: temperature affects how the body regulates blood flow, fluid balance, and physiological stress. The impact of an increasingly warming climate is making these effects more relevant to everyday health.
At the core of the issue is thermoregulation, which is the body’s capacity to maintain, or regulate, a stable internal temperature. In hot weather, blood vessels near the skin widen, a process known as vasodilation. This helps release heat, but it also increases demands on the cardiovascular system, which can in turn contribute to light-headedness, fatigue, fluid loss, and/or peripheral swelling. In colder conditions, the opposite happens. Blood vessels constrict to conserve heat, a process known as vasoconstriction, which can temporarily reduce local blood flow and sometimes blunt pain sensation.
Plunging into the cold
The physiological responses the body has to the cold can help explain why some people report relief from cold exposure, such as through cold plunging. These “polar dips” have become increasingly popular lately and often involve participants submerging themselves in tubs full of ice or even cutting holes in frozen lakes to go for a dip.
From a research standpoint, there is some evidence that cold-water immersion can reduce delayed-onset muscle soreness after exercise, although the benefits appear to be modest and short-term rather than universal. Although cold exposure may reduce perceived discomfort, it should be viewed as a complementary strategy rather than a stand-alone or primary treatment for chronic pain. That said, if your subjective experience of a plunge leaves you feeling refreshed and invigorated, dive in!
Heat and chronic pain
In Canada, population-based estimates suggest that approximately 18.9 percent of adults live with chronic pain. Prevalence increases substantially with age. Within chronic pain, there are several conditions that are, themselves, very common.
Global Burden of Disease analyses estimate that lower back pain affects approximately 7.5 percent of the global population at any given time. Migraine affects roughly 14 to 15 percent of people worldwide and remains one of the leading causes of disability. Rheumatoid arthritis, a chronic inflammatory joint disease, affects about 0.5 to 1 percent of adults in high-income countries.
Many people with these conditions report that their symptoms fluctuate with weather and temperature, as heat may exacerbate inflammatory processes. Dehydration, which is common in warm climates, can amplify inflammation in the body.
Supporting the body through heat and inflammation
Heat exposure may increase the physiological strain you experience through dehydration and inflammation. Here are some evidence-based strategies that can help mitigate these effects:
Hydration
Adequate hydration supports thermoregulation and reduces cardiovascular and physiological strain during heat exposure, with older adults at higher risk due to reduced thirst sensitivity.
- Drink fluids, such as water or electrolyte drinks, regularly throughout the day.
- Monitor fluid intake by keeping your urine pale yellow or clear—darker urine is a sign you need more water.
Anti-inflammatory nutrition
Certain nutrients are associated with reduced inflammation and may support symptom management.
- Omega-3 fatty acids (such as those found in fatty fish) are associated with reduced inflammatory markers and joint pain.
- Polyphenol-rich foods (such as berries) contribute to antioxidant and anti-inflammatory effects.
- Curcumin (turmeric extract) has demonstrated modest reductions in pain and inflammation.
Pacing and heat exposure
Reducing exertion during peak heat lowers physiological strain and risk of heat-related illness.
- Schedule activity during cooler parts of the day.
- Incorporate rest to prevent cumulative heat stress.
Vulnerable population: older adults
Aging is associated with reduced thermoregulatory capacity, making older adults especially vulnerable to the effects of extreme climates. Older adults tend to have diminished sweating, impaired vasodilation, and a less reliable sense of thirst, all of which can make it more difficult to regulate body temperature. These compounding physiological changes can increase susceptibility to dehydration, heat stress, and negative downstream health effects.
This vulnerability is compounded by the higher prevalence of chronic conditions in later life. Many older adults live with several conditions at the same time, known as multimorbidity, and take medications that can impair thermoregulation and/or fluid balance.
Diuretics, antihypertensives, and anticholinergic medications can all increase sensitivity to heat. These intersecting risks mean that heat exposure is not simply uncomfortable but also potentially hazardous.
Epidemiological evidence reinforces this point. Heat waves are associated with increased morbidity and mortality, with disproportionate impacts on older populations. The Lancet has reported that heat-related mortality among adults aged 65 and older has increased substantially in recent decades.
Mitigating temperature effects
From a practical perspective, several strategies can help mitigate the effects of heat. Maintaining adequate hydration is essential, particularly for older adults who may not experience thirst as readily. Pacing activity during hot periods can prevent symptom exacerbation. Access to cool environments, whether through air conditioning or shaded spaces, can reduce physiological strain.
As climate patterns continue to change, heat is becoming a more consistent feature of daily life. Recognizing its effects on the body, particularly among older adults and those living with chronic pain, is an important step in adapting to this reality. Paying attention to temperature is no longer simply about comfort. It is also part of a broader, evidence-informed approach to maintaining health and well-being over time.
Supplements for pain and inflammation
Omega-3 fatty acids
Meta-analysis evidence indicates small reductions in joint pain and use of nonsteroidal anti-inflammatory drugs in people with inflammatory conditions such as rheumatoid arthritis who supplement with omega-3s.
Curcumin
Systematic reviews of randomized trials on the turmeric extract show reduced pain and improved function in osteoarthritis, with effects comparable to some non-prescription analgesics.
Vitamin D
Meta-analytic evidence has found a greater mean decrease in pain score with vitamin D supplementation compared with placebo in people with chronic pain.
Magnesium
A meta-analysis of randomized trials reported reductions in migraine frequency and severity with supplementation.
Collagen peptides
Systematic review evidence suggests modest improvements in joint pain, particularly in people with osteoarthritis, with supplementation.
Even the toughest systems have limits
Resilient corals are shrinking as oceans warm. Under prolonged heat-related stress, corals lose their energy-producing symbiotic algae, a phenomenon known as bleaching, slowing growth and, in some cases, leading to starvation and mortality.
Similar principles apply to us. The human body can tolerate short periods of heat through sweating and increased blood flow, but sustained exposure places strain on these systems. Just as short-term stress is manageable, chronic stress can take a serious toll. Similarly, over time, dehydration, cardiovascular load, poor sleep, and inflammation can accumulate, worsening fatigue and chronic conditions.
Just as stress accumulates, it’s not a single hot day that has a major impact but rather repeated or prolonged exposure to heat that pushes both ecosystems and human physiology beyond their limits.
This article was originally published in the July 2026 issue of alive magazine.
