What are Heat-Related Illnesses?
Heat-related illnesses happen when your body cannot cool itself down effectively. They range from mild problems like heat rash and muscle cramps to life-threatening emergencies like heat stroke. The good news is that most heat-related illnesses are preventable.
Who Is at Higher Risk?
Some people are more vulnerable to heat-related illness than others. This includes adults over age 65 and young children or infants, as well as people with chronic medical conditions such as heart disease, lung disease, kidney disease, diabetes, or obesity. People taking certain medications—including diuretics ("water pills"), blood pressure medications, antihistamines, or psychiatric medications—should ask their doctor whether those medications increase their heat risk. Pregnant women, people who work or exercise outdoors, and people who aren't yet acclimatized to hot weather are also at higher risk, as are people who live alone or have limited mobility and anyone who has had a previous heat-related illness.
Know the Warning Signs
Mild heat illness shows up as heat rash—itchy or painful small blisters on the skin, especially on the neck, chest, or groin—or as heat cramps, which are painful muscle cramps in the legs, arms, or abdomen during or after activity in the heat. If this happens, move to a cool area, rest, drink water or a sports drink, and gently stretch cramped muscles. Heat rash usually resolves on its own if you wear loose clothing and avoid heavy lotions or creams on the affected area.
Heat exhaustion is more serious and should be taken seriously. Watch for heavy sweating, weakness or fatigue, headache, nausea or vomiting, dizziness or lightheadedness, cool clammy skin, and a fast heartbeat. If these occur, stop all activity immediately and move to a cool, shaded, or air-conditioned area. Remove excess clothing, drink cool water or a sports drink, and apply cool wet cloths to the skin or take a cool shower. Lie down and elevate your legs, and if symptoms don't improve within 15 to 20 minutes, seek medical attention.
Heat stroke is a medical emergency. Signs include confusion, slurred speech, agitation, or bizarre behavior; loss of consciousness or seizures; hot skin that may be dry or sweaty; a body temperature of 104°F (40°C) or higher; and a rapid heartbeat and breathing. If you suspect heat stroke, call 911 immediately. While waiting for help, move the person to the coolest area available and cool them as quickly as possible—immerse them in cold water if available, or apply ice packs to the neck, armpits, and groin. Do not give fluids by mouth if the person is confused or unconscious.
How to Prevent Heat-Related Illness
Staying cool means spending the hottest parts of the day, typically 10 a.m. to 4 p.m., in air-conditioned spaces; if you don't have air conditioning at home, a library, shopping center, or community cooling center can help. Cool showers or baths also help, and while fans can provide relief, they may not be enough once temperatures exceed 99°F (37°C).
Staying hydrated means drinking water throughout the day rather than waiting until you feel thirsty. Water is sufficient for activities lasting less than an hour, but for longer activities, a sports drink with electrolytes can help replace salt lost through sweat. It's best to avoid alcohol and heavily caffeinated beverages, since both can contribute to dehydration.
Dressing appropriately means wearing lightweight, loose-fitting, light-colored clothing along with a wide-brimmed hat and sunglasses outdoors. Sunscreen matters too, since sunburn impairs your skin's ability to cool itself for up to seven days.
Being smart about activity means limiting outdoor exercise and heavy work during peak heat hours, and taking frequent breaks in the shade or a cool area if you must be active in the heat. If you're not used to the heat, ease into outdoor activity gradually over 7 to 14 days to let your body acclimatize.
Looking out for others matters as well—check on elderly neighbors, relatives, or friends who live alone, especially during heat waves, and never leave children or pets in a parked car, even for a few minutes.
When to Call Your Doctor or Seek Emergency Care
Call 911 or go to the emergency room if you or someone else experiences confusion, difficulty speaking, or unusual behavior; loss of consciousness, even briefly; seizures; a body temperature of 104°F (40°C) or higher; or heat exhaustion symptoms that don't improve after 15 to 20 minutes of cooling and rest.
Call your doctor's office if you experience repeated episodes of heat cramps, heat exhaustion symptoms that have resolved but you'd like guidance on returning to activity, concerns about whether your medications increase your risk in the heat, dark-colored urine or significantly decreased urination after heat exposure (which may indicate dehydration or kidney problems), or a heat rash that becomes increasingly red, swollen, or painful (which may indicate a skin infection).
