Did you know that your body’s ability to cool off diminishes with aging? That’s why older people are especially susceptible to heat-related ailments such as heat exhaustion and heatstroke when outside temperatures climb. And because excessive heat can impair judgment and cause confusion, you should take precautions to protect yourself from being overcome by heat before you feel too hot.
The body’s cooling system
The body’s thermostat is in a small area of the brain called the hypothalamus. When the hypothalamus senses that body temperature is too high, because of either the weather or an illness, it increases sweat production and dilates blood vessels in the skin. Sweating cools the body through evaporation. Dilating blood vessels brings warm blood from the body’s core toward the surface, permitting heat to be transferred to the environment.
Normal aging reduces the effectiveness of those mechanisms by raising the temperature threshold for sweating, thirst, and heat-related discomfort—especially during waves of hot, humid weather.
Heat-related conditions
Hyperthermia is the general name given to a variety of heat-induced illnesses.
Heat cramps are painful muscle spasms in the legs, arms, or abdomen following strenuous activity in hot weather. Such cramps occur when the body loses water and salt (the two major components of sweat) because of profuse sweating. Additional symptoms can include fatigue and thirst.
Heat syncope is sudden dizziness or fainting that can occur after standing for an extended period in the heat, upon suddenly standing after prolonged sitting in the heat, and immediately after exercising in the heat. Signs and symptoms include pale and sweaty skin, a slowed heart rate, light-headedness, and visual disturbances. Body temperature is normal to slightly elevated.
Heat exhaustion (which can lead to heatstroke; see below) occurs when the body temperature rises, typically to 101°F to 104°F. Pulse and breathing rates may be normal or rapid. Signs and symptoms include:
- Weakness or fatigue
- Nausea or vomiting
- Profuse sweating
- Cold and clammy skin
- Darker than normal urine
- Dizziness, light-headedness, or loss of consciousness
- Headache
- Blurred vision
Heatstroke is a medical emergency. It occurs when body temperature rises dangerously high (above 104°F) and can’t cool down. High body temperature can cause irreversible brain damage. If not treated promptly, heatstroke can lead to seizures, coma, and death.
Classic heatstroke occurs most commonly during heat waves and in people older than 70 who have underlying medical conditions and an impaired ability to get cool or hydrated. Drugs, both prescription and recreational, frequently play a role (see below).
Another form, exertional heatstroke, mostly affects healthy, active people, particularly young athletes, within hours of exercising or overexerting themselves in hot weather.
Heatstroke is most likely to develop when the humidity is high and temperatures are 90°F or above. Humidity makes it feel hotter than it is. The heat index that you hear meteorologists refer to indicates how hot the combination of temperature and humidity feels to the human body.
The onset of heatstroke can be rapid, with progression to a life-threatening state within minutes. Signs and symptoms vary and can include:
- Hot, dry skin (often with no sweating)
- Rapid pulse
- Flushed face
- Rapid, shallow breathing
- Confusion or disorientation
- A change in behavior, such as agitation or combativeness
- Dizziness, fainting, or loss of consciousness
- Nausea or vomiting
- Staggering gait
If you suspect someone has heatstroke, call 911 right away. If not treated promptly, heatstroke can damage the brain, heart, lungs, liver, and kidneys. Heatstroke can also be fatal: The longer treatment is delayed, the higher the risk of death.
Each year, more than 600 deaths in the United States are attributed to exposure to extreme heat—though the official statistics are very likely an underestimate. The Federal Emergency Management Agency (FEMA) defines extreme heat as “a period of excessively hot weather, with higher than average temperatures for a particular region, combined with high humidity.”
Risk factors in older adults
Health factors that can increase the risk for classic hyperthermia include:
- Poor circulation
- Dehydration
- Obesity
- Inefficient sweat glands, which become more common with age
- Chronic illnesses such as heart, lung, and kidney diseases; diabetes; respiratory disorders; and skin disorders such as psoriasis, eczema, and scleroderma
- A salt-restricted diet
- Use of certain drugs that affect the body’s hydration status and response to heat, including tricyclic antidepressants; anticholinergics, such as antihistamines and antiparkinson agents; and certain heart and blood pressure drugs, notably beta-blockers, calcium channel blockers, and diuretics
- Mental states that affect judgment, such as dementia
- Disabilities or illnesses that restrict mobility, such as being bedridden or unable to take care of oneself
Lifestyle factors that increase susceptibility to classic heatstroke include:
- Living in an extremely hot residence
- Living alone or in social isolation
- Not having convenient access to transportation, which prevents people from seeking respite in air-conditioning
- Overdressing, especially among older people, who may not feel the effects of a heat wave because our perception of heat decreases as we age
- Drinking alcoholic beverages
Playing it safe
As soon as the air temperature starts to rise, take the following steps to ward off heat-related illness:
- Stay indoors in air-conditioning as much as possible. Being in air-conditioning, even if only for a few hours, significantly reduces the risk of hyperthermia. If you don’t have air-conditioning, try to keep your home cool by keeping shades or curtains drawn during the hottest part of the day, opening windows at night, and using fans. Run errands, exercise, or do other outdoor activities early to avoid the hottest part of the day. Spend time in air-conditioned environments, such as movie theaters, libraries, shopping malls, and senior centers (be sure to follow proper Covid-safety practices). Your community may provide cooling centers where you can spend the day.
- Stay hydrated. Drink water throughout the day, whether you feel thirsty or not: Older adults are less likely than younger people to recognize thirst. Avoid alcoholic beverages. If you’re on a diet that restricts liquids or have heart, kidney, or liver disease or epilepsy, check with your doctor first before you increase your fluid intake.
- Modify physical activity. Avoid strenuous exercise during heat waves. Adjust how much you walk, garden, and so forth. In some instances, it may be possible to exercise early in the morning or in the evening. Be sure to rest at the first sign of feeling fatigued, light-headed, or hot.
- Take baths and showers. Because water conducts heat away from the body, taking cool or tepid baths and showers is a good cooling technique.
- Wear appropriate clothing. Loose-fitting, light-colored, lightweight garments made of natural fibers that “breathe,” such as cotton, are best. A wide-brimmed hat can provide shade and keep your head cool.
- Talk with your doctor about your medications. It may be possible to alter a drug or dosage that could cause a problem. But under no circumstances should you change your medication on your own.
First aid for hyperthermia
Heat syncope and heat cramps can usually be relieved by drinking plenty of water and resting in a cool place. If symptoms don’t go away within 30 minutes, seek medical attention.
To treat heat exhaustion and stop it from turning into heatstroke, take these steps:
- Move the person out of the sun into a cool place, preferably one that’s air-conditioned.
- Have the person lie down on their back, with legs elevated (feet slightly higher than heart level).
- Remove any unnecessary clothing and loosen any that’s tight.
- Offer cool water (not ice cold, which can cause stomach cramps), fruit juice, or a sports drink with electrolytes like Gatorade to replenish sodium lost during sweating. In lieu of a sports drink you can use a solution made by adding ¾ teaspoon table salt and 2 tablespoons sugar to a quart of water. You can also use an oral rehydration drink mix, which contains electrolytes and sugar. Don’t offer salt tablets since they can induce vomiting and increase dehydration. Avoid alcoholic or sugary beverages.
- Apply an ice pack, a cold compress, or cool, wet towels to the back of the neck, armpits, and groin, to help cool the person.
- Splash or spray the person with cool water (such as with a garden hose), then fan the person’s skin or have them sit in front of an electric fan.
- Watch the person carefully for any changes in condition. If symptoms worsen or don’t improve within 30 minutes, or if the person has an underlying heart disorder, call 911.
- Once the person is feeling well enough, encourage them to shower, bathe, or sponge off with cool water.
If there are signs or symptoms of heatstroke, emergency assistance should be sought immediately. Without medical attention, heatstroke can be deadly. After you call 911, try to keep the person cool using the techniques outlined above. However, offer water only if the person is alert and can swallow. You can immerse a person in a tub of cool water or in a body of water such as a lake or a stream.
