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Dr. Andrew Rynne
Dr. Andrew Rynne

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Exp 50 years

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Article Home Adult and Senior Health Heat-Related Illnesses: Heat Exhaustion and Heat Stroke

Heat-Related Illnesses: Heat Exhaustion and Heat Stroke

It’s great to be enthusiastic about sports and exercise, but when the weather is hot you need to do it all with caution. It’s not only about avoiding discomfort or an unwanted tan. Too much heat can make you seriously ill. You can stay safe in the heat by understanding heat-related illnesses and taking some precautions to avoid them. This article discusses symptoms, causes, risk-factors, treatment and prevention of heat-related illnesses.


It’s great to be enthusiastic about sports and exercise, but when the weather is hot you need to do it all with caution. It’s not only about avoiding discomfort or an unwanted tan. Too much heat can make you seriously ill. You can stay safe in the heat by understanding heat-related illnesses and taking some precautions to avoid them.

What Causes Heat-Related Illnesses?

Everyday your body makes countless adjustments to function smoothly irrespective of changes in the environment. The body’s cooling mechanism is one such homeostatic system that keeps its temperature maintained in hot weather. Your body accomplishes this by making more blood to circulate through the skin. However this leaves less blood available for your other organs and puts some extra load on your heart. Usually, these changes are able to cool you down without causing untoward symptoms. But under extreme conditions the system may become overwhelmed causing heat-related illnesses, such as heat exhaustion or heatstroke. High humidity increases the risk of heat-related illnesses by curbing the evaporation of sweat, thus putting extra pressure on the cooling mechanism.

What is Heat Exhaustion?

Heat exhaustion is the milder of the two heat-related illnesses. It usually occurs in a person exercising, playing or undertaking some other strenuous activity in hot weather. Its symptoms are somewhat similar to extreme exhaustion, and hence the name. A person experiencing heat exhaustion may begin to feel faint or dizzy. He may also feel worried and have a rapid heart rate. Other signs and symptoms observed include a cool and pale skin, profuse sweating, low blood pressure, headache and very little, dark colored urine. Body temperature maybe moderately increased (101-102 degrees F, but not above 104 degree F) which, is actually not fever, but caused by the heat.

What is Heat Stroke?

Heat stroke is the most severe form of heat illness. It is a medical emergency and can kill you if not treated promptly. A person with a heatstroke has a very high temperature (106 degrees F or higher), which can cause damage to the brain or other internal organs. Unlike heat exhaustion, heat stroke causes marked alteration in mental status (person is confused, delirious, unconscious, or having seizures). Skin usually feels hot and dry. Heat stroke usually occurs in a person predisposed to it because of an underlying medical condition or medication. Infants, elderly, and bed-ridden patients who are unable to modify their environment are more prone to heat stroke.

How is Heat Exhaustion Treated?

Symptoms of heat exhaustion usually resolve with some first-aid and care at home. If you think you could be having heat exhaustion:

  • Get out of the heat and into a shady or air-conditioned location.
  • Lie down and elevate your legs and feet slightly.
  • Loosen or remove your clothing to let your body cool.
  • Drink cool water or other nonalcoholic beverage without caffeine.
  • Do NOT drink alcohol. Alcohol can make heat exhaustion worse.
  • Cool your body by spraying or sponging with cool water and fanning.
  • If you are not able to keep down fluids because of vomiting, see a doctor as you may need intravenous fluids.

Heat exhaustion can quickly progress to heatstroke. If you do not feel better within 30 minutes, or fever greater than 102 F (38.9 C), fainting, confusion or seizures occur, seek emergency medical help.

What to Do In Case Of a Heat Stroke?

Heat stroke is a medical emergency. Call for an ambulance immediately if you suspect heat stroke. Take the following measures till help arrives:

  • Take the affected person to a cool, shady place quickly.
  • Remove the person’s unnecessary clothing.
  • Try placing him or her in a cool (not cold) bath of water if he or she is conscious and can be attended continuously (head needs to held above water at all times).
  • Otherwise, moisten the skin with lukewarm water and use a fan to blow cool air across the skin. The evaporation of water will promote faster cooling.
  • Cold compresses to the torso, head, neck, and groin will also speed cooling. Avoid wrapping the person in wet towels as it can actually hinder heat loss.
  • Give something to drink by mouth only if the person has a normal mental state. Do not try to force a delirious or unconscious person to drink.

How to Avoid Heat-Related Illnesses?

Some basic precautions can protect you from getting sick because of the heat:

  • Have a reasonable approach to physical exertion in hot and humid weather. Know that too much heat can make you seriously ill.
  • Limit vigorous outdoor activities for cooler times of the day -- before 10:00 a.m. and after 6:00 p.m.
  • If you have recently moved to a place hotter than what you are used to, start outdoor exercise with caution, giving your body enough time to adapt.
  • Drink water every 15 to 20 minutes, even if you don't feel thirsty. Your urine should be clear and pale. Dark-colored urine is an indication that you're not drinking enough fluids.
  • Avoid alcohol and caffeinated beverages. They can dehydrate you by promoting water loss.
  • Wear lightweight, loose fitting clothing that allows more air pass to over your body. Avoid dark colors, which can absorb the heat.
  • If you are on any long term medication, ask your doctor if it puts you at higher risk of heat related illnesses.

Recognize the Warning Signs

When exposed to a hot environment, be aware of early signs of heat-related illnesses. Muscle cramps, particularly in lower leg muscles (heat cramps) are an early symptom of heat related illness. Weakness, headache, dizziness or nausea could also signal impending heat exhaustion. If you get these symptoms, you can avoid heat exhaustion by immediately getting out of the heat.

Medicines and Heatstroke Risk

Some medicines hinder your body’s ability to deal with the heat and put you at a higher risk of heat stroke. Some medicines that may have such an effect include:

  • Allergy medicines (antihistamines)
  • Some blood pressure and heart medicines (beta blockers and vasoconstrictors)
  • Diet pills (amphetamines)
  • Laxatives
  • Mental health medicines (antidepressants and antipsychotics)
  • Seizure medicines (anticonvulsants)
  • Thyroid pills
  • Water pills (diuretics)

Talk to your doctor to know if any medication that you are taking might put you at an increased risk of a heat-related illness.


Having heat exhaustion or heatstroke makes your body more sensitive to heat for about a week afterwards. You should take it easy and avoid being in a hot environment during this time. Those recovering from a heat stroke should consult their family physician before resuming normal activities.