Who is most at risk for hyperthermia?

September 25, 2025 •

4 min read

Hyperthermia, the dangerous overheating of the body, is a preventable but potentially fatal condition. Anyone can be affected by extreme heat, but certain individuals and groups face a significantly higher risk due to various physiological, medical, and environmental factors.

Quick Summary

Several groups are at heightened risk for hyperthermia, including infants, older adults over 65, outdoor laborers, and individuals with chronic medical conditions like heart disease or obesity. Factors such as certain medications, dehydration, and high humidity also increase vulnerability for heat-related illnesses.

Key Points

Older Adults: The elderly, especially those over 65, are at high risk due to poorer temperature regulation, chronic health issues, and medication effects.
Infants and Children: Young children's bodies are less efficient at cooling and they depend entirely on caregivers to manage their environment and hydration.
Outdoor Laborers and Athletes: Those involved in strenuous physical activity in hot conditions produce significant internal heat and lose fluids rapidly through sweating.
Chronic Illnesses: Conditions like heart disease, diabetes, and obesity impair the body's natural cooling responses, increasing vulnerability.
Certain Medications: Drugs such as diuretics, antidepressants, and blood pressure medications can interfere with sweating and body temperature control.
Prevention is Key: Staying hydrated, seeking cool environments, and avoiding peak heat hours are crucial preventive measures for all at-risk groups.

Vulnerable Populations

Certain individuals are less able to regulate their body temperature or respond appropriately to heat stress, placing them in a high-risk category for hyperthermia. Understanding these groups is the first step toward effective prevention.

Older Adults

Adults aged 65 and older are particularly susceptible to hyperthermia for several reasons:

Decreased Temperature Regulation: The body's ability to adjust to sudden temperature changes declines with age.
Chronic Health Conditions: Many older adults have medical conditions, such as heart disease, diabetes, or high blood pressure, that can interfere with the body's normal response to heat.
Medications: Prescription drugs, including diuretics (water pills) and certain blood pressure or psychiatric medications, can affect sweating and the body's ability to control its temperature.
Reduced Awareness: Older adults may be less aware of changes in temperature or less likely to notice their own symptoms of overheating.
Social Factors: Those who live alone or in homes without air conditioning are at increased risk, especially during heat waves.

Infants and Young Children

Infants and young children are also highly vulnerable to extreme heat:

Inefficient Thermoregulation: Their bodies have a higher metabolic rate and are less efficient at sweating compared to adults, making it harder for them to cool down.
Reliance on Caregivers: They are completely dependent on others to regulate their environment, including ensuring proper clothing, hydration, and shade.
Higher Surface Area-to-Mass Ratio: A child's larger surface area relative to their body mass means they absorb heat from their environment more quickly than adults.

Athletes and Outdoor Workers

People who engage in intense physical activity, whether for work or sport, are at elevated risk:

Increased Internal Heat Production: Strenuous exertion generates a significant amount of metabolic heat, which can overwhelm the body's cooling mechanisms.
Dehydration: Heavy sweating during activity leads to rapid fluid loss, which impairs the body's ability to cool itself effectively.
Environmental Exposure: Individuals like construction workers, farmers, and athletes are exposed to direct sunlight and high temperatures for extended periods.

Individuals with Chronic Medical Conditions

Pre-existing health issues can compromise the body's ability to manage heat:

Cardiovascular Disease: Conditions like heart disease and high blood pressure force the heart to work harder to pump blood, which is already strained in hot weather.
Obesity: Excess body weight can cause the body to retain more heat.
Diabetes: This condition can affect blood vessel function and hydration, complicating the body's response to heat.
Mental Health Conditions: Certain psychiatric medications can suppress the body's thermoregulation and sweat response.

Comparison of Risk Factors

Below is a table comparing the primary risk factors for different high-risk groups to illustrate their varied vulnerabilities.


Risk Factor	Older Adults	Infants/Children	Athletes/Outdoor Workers	Chronic Conditions	Medication Use
Inefficient Temperature Regulation	High	High	Low (unless untrained)	High (condition dependent)	High (drug dependent)
Dehydration Susceptibility	High (reduced thirst sensation)	High (reliant on others)	High (high sweat rate)	High (condition/drug dependent)	High (drug dependent)
Physical Exertion	Low (typically)	Low (typically)	High	Varies	Varies
Medication Impact	High	Low	Low	High	High
Environmental Exposure	Low (typically indoors)	Low (typically indoors)	High	Varies	Varies
Behavioral Awareness	Low	Low	High	Low (mental health)	Low (mental health)

Mitigating the Risk of Hyperthermia

For high-risk individuals, proactive measures are crucial for preventing hyperthermia during hot weather.

Staying Hydrated and Cool

Drink plenty of fluids throughout the day, even if not thirsty. Water is best, but electrolyte drinks can help replenish minerals lost through sweat.
Avoid dehydrating beverages like alcohol and caffeine.
Spend time in air-conditioned environments during the hottest parts of the day. Utilize public spaces like malls or libraries if home cooling is inadequate.
Take cool showers, baths, or apply wet cloths to the skin to help lower body temperature.

Adjusting Activities and Environment

Limit or avoid strenuous physical activity during peak heat hours (typically late afternoon).
Schedule outdoor tasks for the cooler morning or evening hours.
Wear loose-fitting, light-colored clothing made from breathable fabrics.
Never leave a child, pet, or vulnerable adult in a parked car, even with windows cracked.

Medical and Social Considerations

Check on elderly neighbors, friends, and relatives who live alone, especially during heat waves.
Discuss heat risks with a healthcare provider, especially for those with chronic conditions or those on medications that affect thermoregulation.
Learn to recognize the symptoms of heat-related illness, such as dizziness, headache, nausea, and confusion.

Conclusion

While anyone can experience a heat-related illness, understanding who is most at risk for hyperthermia is critical for targeted prevention. Infants, older adults, outdoor workers, athletes, and individuals with underlying medical conditions or those on specific medications require special attention during periods of extreme heat. By implementing simple yet effective strategies like staying hydrated, seeking cool environments, and modifying activity levels, we can significantly reduce the risk and protect those most vulnerable. For further resources and information on heat safety, consult the Centers for Disease Control and Prevention guidelines. CDC.gov

Glossary of Heat-Related Conditions

Hyperthermia: An elevated body temperature that results from the body's inability to dissipate heat effectively.
Heat Exhaustion: A moderate heat-related illness caused by excessive fluid and salt loss, characterized by heavy sweating, weakness, and nausea.
Heat Stroke: A life-threatening medical emergency where the body's temperature is critically high (typically above 104°F) and the central nervous system begins to fail.
Heat Cramps: Muscle spasms that can occur during intense exercise in hot conditions due to electrolyte imbalance.

Frequently Asked Questions

A fever is a controlled rise in body temperature in response to an infection, triggered by the hypothalamus. Hyperthermia, however, is an uncontrolled elevation of body temperature caused by the body's failure to regulate heat effectively, often due to environmental factors or intense activity.

Yes, several classes of medications, including diuretics, beta-blockers, some antidepressants, and psychiatric drugs, can interfere with the body's ability to sweat and regulate temperature, thereby increasing hyperthermia risk.

Older adults are more vulnerable because their bodies don't adapt as well to temperature changes, they often have chronic medical conditions that affect heat response, and they may not recognize their own symptoms of overheating as quickly.

Outdoor workers can protect themselves by taking frequent breaks in shaded or air-conditioned areas, drinking plenty of water, wearing loose and light-colored clothing, and avoiding the most strenuous tasks during peak heat hours.

Early signs of heat-related illness include heavy sweating, muscle cramps, headache, dizziness, and nausea. Recognizing these symptoms early and taking action, such as cooling down and rehydrating, can prevent more severe conditions like heatstroke.

Yes, people living in high-density urban areas, especially in neighborhoods with less green space and limited access to air conditioning, are at higher risk due to the 'urban heat island effect,' where concrete and pavement trap heat.

Heatstroke is a medical emergency. If someone shows signs like confusion, loss of consciousness, or a temperature over 104°F, call emergency services immediately. While waiting for help, move them to a cool place and begin active cooling with ice packs or a cool bath.