Why Heat Gets Harder as We Age
McMaster University • May 20, 2026
Overview
Summer heat can affect older adults very differently than younger people. As we age, the natural cooling systems our bodies rely on become less efficient, making us more susceptible to heat-related illnesses such as heat exhaustion and heat stroke. Understanding why this happens — and what you can do about it — is the first step toward staying safe.
Why Heat Affects Older Adults Differently
The body relies on several interacting systems to stay cool during hot weather. Aging can impair all three of these systems — thermoregulation, circulation, and fluid balance — often simultaneously. Here are six key age-related changes that affect heat response:
- Thermoregulation: The body’s internal thermometer becomes less accurate with age, meaning cooling responses such as sweating may be triggered more slowly or less strongly.
- Circulation: Aging reduces the heart’s capacity to pump blood efficiently to the skin, which is the primary route for releasing body heat.
- Fluid balance: Older adults have a diminished sense of thirst, reduced kidney efficiency, and lower baseline body water — all of which increase dehydration risk.
- Sweat glands: The number and output of sweat glands decline with age, reducing the body’s most effective cooling mechanism.
- Skin changes: Aging skin has fewer surface blood vessels, limiting the body’s ability to radiate heat outward.
- Chronic illness: Common conditions such as diabetes, heart disease, and kidney disease can further impair temperature regulation.
Is Your Medication Making You More Sensitive to Heat?
Many common medications interfere with how the body regulates temperature or maintains fluid balance. If you take any of the medications listed below, speak with your doctor, nurse practitioner, or pharmacist about your personal risk — especially before heat waves or strenuous outdoor activity.
|
Type of Medication |
Why It Increases Your Risk |
|
Heart & Blood Pressure (e.g., Beta-blockers) |
Can make it harder for your heart to pump warm blood to the skin for cooling. |
|
Diuretics (“Water Pills”) |
Help your body eliminate salt and water, which can lead to dehydration or salt imbalances in the heat. |
|
Antidepressants & Anti-anxiety |
Some can prevent you from sweating or change how your brain’s thermostat reacts to heat. |
|
Allergy & Cold Relief (Antihistamines/Decongestants) |
Can stop sweating or prevent blood vessels in your skin from dilating to release heat. |
|
Parkinson Disease Medications |
Many treatments can directly inhibit your ability to sweat. |
|
Memory & Alzheimer Disease Medications |
Some treatments cause side effects like diarrhea or vomiting, which can lead to rapid dehydration. |
|
Antipsychotics |
Can prevent sweating and, in some cases, cause your body temperature to rise on its own. |
Beat the Heat: Summer Safety Guide
Staying safe in hot weather starts with understanding your personal risk factors and taking consistent steps to stay cool and hydrated. The following strategies are particularly important for older adults:
Stay Hydrated
- Drink water regularly throughout the day — do not wait until you feel thirsty.
- Avoid alcohol and caffeine, which can accelerate dehydration.
- Eat water-rich foods such as cucumber, watermelon, and celery.
Keep Cool
- Spend time in air-conditioned spaces during peak heat hours (typically 11 a.m. to 4 p.m.).
- Use fans, cool showers, and damp cloths on pulse points (wrists, neck) to reduce body temperature.
- Wear lightweight, loose-fitting, light-coloured clothing.
- Keep blinds or curtains closed during the hottest parts of the day to reduce indoor heat.
Know the Warning Signs
- Heat exhaustion: heavy sweating, weakness, cold or clammy skin, weak pulse, nausea, or fainting.
- Heat stroke (call 911 immediately): body temperature above 39°C (103°F), hot and dry skin, rapid strong pulse, or unconsciousness.
Check In and Plan Ahead
- Ask a family member, friend, or neighbour to check on you on hot days.
- Know the location of your nearest public cooling centre.
- Talk to your healthcare provider about whether any of your medications increase heat sensitivity.
|
Key Takeaway Aging, chronic illness, certain medications, and dehydration can all increase the risk of heat-related illness. Staying hydrated, keeping cool, and consulting your health professionals about medication risks are the most effective steps you can take to stay safer in hot weather. |
