University Health Service

Girl drinking from a water bottle on a hot day

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Why chill out? People can suffer heat-related illnesses when they are unable to get cool. The body normally cools itself by sweating, but when humidity is high and sweat does not evaporate quickly, body temperature can rise rapidly. Very high body temperatures may damage the brain or other vital organs. Other factors that increase risk are include age, obesity, fever, dehydration, heart disease, mental illness, poor circulation, sunburn, and prescription drug and alcohol use.

Heat-related illness:

Heat exhaustion is a milder form of heat-related illness that can develop after several days of exposure to high temperatures and inadequate or unbalanced replacement of fluids. It is the body's response to an excessive loss of the water and salt contained in sweat. Those most prone to heat exhaustion are the elderly, people with high blood pressure, and people working or exercising in a hot environment.

Warning signs of heat exhaustion include:

  • Heavy sweating
  • Paleness
  • Muscle cramps
  • Tiredness
  • Weakness
  • Dizziness
  • Headache
  • Nausea or vomiting
  • Fainting
  • Skin may be cool and moist
  • Pulse will be fast and weak
  • Breathing will be fast and shallow

If heat exhaustion is untreated, it may progress to heat stroke. Seek medical attention immediately if symptoms are severe, or if the person has heart problems or high blood pressure.

Otherwise, help the person to cool off, and seek medical attention if symptoms worsen or last longer than one hour.

Cooling measures that may be effective include the following:

  • Cool, nonalcoholic beverages
  • Rest
  • Cool shower, bath, or sponge bath
  • An air-conditioned environment
  • Lightweight clothing

Heat stroke is defined as core body temperature of more than 105° F and brain dysfunction. It occurs when the body is unable to regulate its temperature. The body's temperature rises rapidly, the sweating mechanism fails, and the body is unable to cool down. Body temperature may rise to 106° F or higher within 10-15 minutes. Heat stroke can cause death or permanent disability if emergency treatment is not provided.

Warning signs of heat stroke vary but may include the following:

  • Rapid, strong or weak pulse
  • An extremely high body temperature (above 103° F or 39.4° C, measured orally)
  • Red, hot, and dry skin (no sweating)
  • Throbbing headache
  • Dizziness
  • Nausea
  • Confusion
  • Unconsciousness

If you see any of these signs, you may be dealing with a life-threatening emergency. Call 911 while you begin cooling the person.

Get him/her to a shady area.

Cool him/her rapidly using whatever methods you can. For example, immerse the person in a tub of cool water; place the person in a cool shower; spray him/her with cool water from a garden hose; sponge the person with cool water; or if the humidity is low, wrap him/her in a cool, wet sheet and fan him/her vigorously.

Monitor body temperature, and continue cooling efforts until the body temperature drops to 101-102° F.

Sometimes a person's muscles will begin to twitch uncontrollably as a result of heat stroke. If this happens, prevent self-injury but do not place any object in the mouth and do not give fluids. If there is vomiting, make sure the airway remains open by turning the person on his/her side.

Heat cramps usually affect people who sweat a lot during strenuous activity. This sweating depletes the body's salt and moisture. The low salt level in the muscles may be the cause of heat cramps. Heat cramps may also be a symptom of heat exhaustion.

Heat cramps are muscle pains or spasms—usually in the abdomen, arms, or legs—that may occur in association with strenuous activity. If you have heart problems or are on a low-sodium diet, get medical attention for heat cramps.

If medical attention is not necessary, take these steps:

Stop all activity, and sit quietly in a cool place.

Drink clear juice or a sports beverage.

Do not return to strenuous activity for a few hours after the cramps subside, because further exertion may lead to heat exhaustion or heat stroke.

Seek medical attention for heat cramps if they do not subside in one hour.

Sunburn damages the skin and should be avoided. Although the discomfort is usually minor and healing often occurs in about a week, more severe sunburn may require medical attention.

Consult a health care provider if the sunburn affects an infant younger than one year old or if these symptoms are present:

  • Fever
  • Fluid-filled blisters
  • Severe pain

Also, remember these tips when treating sunburn:

  • Avoid repeated sun exposure.
  • Apply cold compresses or immerse the sunburned area in cool water.
  • Apply moisturizing lotion to affected areas. Do not use salve, butter, or ointment.
  • Do not break blisters.

Heat rash is a skin irritation caused by excessive sweating during hot, humid weather. It can occur at any age but is most common in young children.

Heat rash looks like a red cluster of pimples or small blisters. It is more likely to occur on the neck and upper chest, in the groin, under the breasts, and in elbow creases.

The best treatment for heat rash is to provide a cooler, less humid environment. Keep the affected area dry. Dusting powder may be used to increase comfort.

Beat the heat: suggestions for staying cool

Anyone, even young and healthy individuals, can succumb to heat if they participate in strenuous physical activities during hot weather.

Find air conditioning. See Where to Get Cool on Campus.

Cut back on strenuous outdoor activity. Exercise during the early morning or late evening hours when heat and ozone levels are at the lowest levels of the day.

If you must be outdoors, try to limit your outdoor activity to morning and evening hours. Rest often in shady areas so that your body's thermostat will have a chance to recover.

Drink plenty of hydrating fluids (avoid alcohol). Increase your fluid intake, regardless of your activity level. Don't wait until you're thirsty to drink. (If your health care provider generally limits the amount of fluid you drink or has you on water pills, ask how much you should drink while the weather is hot.) Avoid very cold drinks, because they can cause stomach cramps.

Replace salts and minerals, which are lost through heavy sweating. A sports beverage can replace the salt and minerals you lose in sweat. However, if you are on a low-salt diet, talk with your health care provider before drinking a sports beverage or taking salt tablets.

Wear lightweight, light-colored, loose-fitting clothing. Dress infants and children in cool, loose clothing and shade their heads and faces with hats or an umbrella.

Avoid sunburn, which affects your body's ability to cool itself and causes a loss of body fluids. It also causes pain and damages the skin. Limit sun exposure during mid-day hours and in places of potential severe exposure such as beaches. If you must go outdoors, protect yourself from the sun by wearing a wide-brimmed hat (also keeps you cooler) along with sunglasses, and by putting on sunscreen of SPF 15 or higher (the most effective products say "broad spectrum" or "UVA/UVB protection" on their labels) 30 minutes prior to going out. Continue to reapply it according to the package directions.

Do not leave children or pets in cars. Cars can heat up to dangerous temperatures very quickly.

Take showers or baths or go swimming. U-M offers three pools on campus (North Campus, Central Campus and Intramural Sports Building). See current hours at the U-M Recreational Sports website.

Where to get cool on campus: The following buildings offer air-conditioning. Follow links for hours -- many are open late or even 24 hours/day.

Campus Computing Sites -- Note: the MI Union Computing Center is accessible via Card Reader through West Quad Courtyard 24 hours/day

Duderstadt Center on North Campus - open 24 hours

Michigan Union

Palmer Commons Plaza (Windows Room/lobby on 3rd floor)

Pierpont Commons on North Campus

U-M Recreation Sports Building Hours and Swimming Pool Hours

Shapiro Undergraduate Library - open 24 hours

For more information:

To use UHS, see Schedule an Appointment (UHS offers options for urgent health concerns)

Nurse Advice by Phone is available day and night, which may save a trip to UHS or the ER.