Personal Risk Factors for Heat Stress: What You Need to Know
Part 3 of Our Cooling Plan Series

Understanding your personal risk factors is critical to staying safe during heat stress. In this part of our Cooling Plan Series, we focus on YOU, highlighting the key factors that make some people more vulnerable to heat-related illnesses. Knowing your risks, you can create a cooling plan that suits your unique needs.

A Hot Day Isn’t the Same for EVERYBODY!

Why Personal Risk Factors Matter

Not everyone reacts to heat the same way. Your age, health, medications, and even gender can increase your risk of heat exhaustion or heat stroke. Understanding these factors can lower your risk and help you stay safer during hot weather.

Age and Heat Sensitivity

Children and Heat Risk

Children are especially vulnerable to heat stress due to:

• High metabolic rate: Kids generate more body heat as they grow.
• Body composition: Babies have more body fat and less surface area to release heat.
• Lower blood volume: Makes transferring heat away from the core harder.
• Sweating: Children sweat less and start sweating at higher temperatures.
• Hydration: Kids often don’t recognize when they’re thirsty.
  

Tip: Always supervise children during hot weather and encourage frequent water breaks.

Older Adults and Heat Risk

Older adults are also at higher risk because:

• Slower metabolism: Leads to lower body temperature and less efficient heat regulation.
• Less fat under the skin: Increases sensitivity to temperature changes.
• Reduced blood circulation: Makes it more challenging to cool down.
• Decreased sweating: Sweat glands become less active with age.
• Weaker thirst signals: Older adults may not feel thirsty, increasing the risk of dehydration.

Fact: Adults aged 65+ have the highest rate of heat-related deaths.

CDC Data

Fitness Level and Medical Conditions

• Physical fitness: A healthy heart and reasonable fitness level help your body manage heat better.
• Heart-related conditions: Diabetes, hypertension, POTS, and pregnancy all increase risk. Example: Diabetes can change how your body uses insulin in the heat.
• Neurological conditions: Diseases like lupus, fibromyalgia, and multiple sclerosis (MS) can make you more sensitive to heat.
• MS Note: Heat can trigger symptoms (Uhthoff’s Phenomenon).

 

Medications That Increase Heat Risk

Many common medications, prescription or over-the-counter, can make it harder for your body to handle heat. A significant number of medications, many of which are over-the-counter, can reduce your tolerance to heat. Rarely is this side effect mentioned prominently. 

These include:

• Antihistamines (Zyrtec, Benadryl, Claritin, etc.): Reduce sweating.
• Antidepressants (SSRIs like Prozac): May increase the risk of sweating and dehydration.
• Antipsychotics (Abilify, Zyprexa): Affect temperature regulation.
• Anticholinergics (used for asthma, COPD, Parkinson’s): Impair sweating.
• Beta blockers and ACE inhibitors: Lower blood pressure and reduce heat tolerance.
• Alcohol: Increases dehydration risk.

Tip: Check your medications and heat sensitivity with your doctor or pharmacist.

 

Acclimatization: Adapting to the Heat

Your body can adjust to heat over time—a process called acclimatization. Acclimation usually takes 7-14 days. During this period, your body gets better at cooling itself, but you’re still at risk until you're fully acclimated. If traveling to a hotter climate, remember that your body needs time to adjust. It is going to “feel” hotter to you than others.

Repeat Heat-Related Illness

If you’ve had a heat-related illness, you’re more likely to experience it again. Previous heat illness can damage organs and reduce your body’s ability to handle heat. There is new information that prolonged exposure to heat has Long-term health effects. Heat can damage your cardiovascular system, kidneys, lungs, brain, nervous system, and skin. Heat can even cause premature aging at the same scale as smoking and drinking alcohol.

Gender Differences in Heat Risk

Studies show that males are at higher risk for heat-related illness. Take extra precautions if you or your loved ones work outside in the heat.

 

"The rate of heat-related deaths among persons aged ≥65 years was 0.7 per 100,000 population, the highest across all age groups." 
Source: CDC

 

Source: CDC

The next risk factor is how fit we are. You might remember from last week's blog that excess heat significantly strains our hearts. The heart must work harder to pump blood to our organs and muscles, and simultaneously move heat from our core to our extremities.

Being in better physical shape means your heart is more efficient at these crucial tasks. Here in Rochester, NY, we often talk about “Heart Attack Snow” because of how strenuous shoveling heavy, wet snow can be on the heart. It’s vital to recognize that heat can have a similar impact if our bodies aren't physically prepared for it. Like snow, there is a thing called Heart Attack Heat. Just like preparing your heart for strenuous snow removal, being physically fit helps your body cope with the heat demands.

How to Use This Information

As children from the '80s, we remember the coach yelling at us that we were weak because we asked for water during practice at triple-digit temps. Thank goodness the good old days are behind us, but our old macho attitudes are misguided and dangerous. Use this information to empower yourself and your body. As we have stated before, there is ONLY prevention. Use your personal information to ask yourself,

There’s no one-size-fits-all rule for heat safety. Ask yourself:

• How am I feeling?
• Have I had enough water?
• Am I putting unnecessary stress on my heart?
• What does my experience tell me?

Stay informed, listen to your body, and adjust your cooling plan based on personal risk factors.

Stay Cool,

The ThermApparel Team

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**This website is provided for educational and informational purposes only and does not constitute providing medical advice. The information provided should not be used for diagnosing or treating a health problem or disease, and those seeking personal medical advice should consult with a licensed physician. Always seek the advice of your doctor or other qualified health provider regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on ThermApparel’s website. If you think you may have a medical emergency, call 911 or go to the nearest emergency room immediately. Neither ThermApparel nor its employees, nor any contributor to this website, makes any representations, express or implied, with respect to the information provided herein or to its use.

ThermApparel is a small business making big waves in the heat sensitivity world by designing the first lightweight, comfortable and invisible cooling vest, UnderCool. Check us out online, on our blog, or on Facebook, Twitter, Pinterest, LinkedIn and Instagram.

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