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What causes heat exhaustion and heatstroke?

Heat exhaustion happens when your body gets too hot. If you don’t treat heat exhaustion, it can lead to heatstroke. This occurs when your internal temperature reaches at least 40°C (104°F). Heatstroke is much more serious than heat exhaustion. It can cause shock, organ failure, or brain damage. In extreme cases, heatstroke can kill you.

SYMPTOMS

Symptoms of heat exhaustion are:

• Muscle cramps
• Heavy sweating
• Pale or cold skin
• Weakness and/or confusion
• Dizziness
• Nausea or vomiting
• Headache
• Fast heartbeat
• Dark-colored urine, which indicates dehydration

In addition to these symptoms, warning signs of heatstroke also include:

• Fever of40°C (104°F) or higher
• A flushed or red skin
• Lack of sweating
• Fast heartbeat
• Trouble breathing
• Fainting
• Seizures

CAUSES

Heat-related illnesses occur when your body can’t keep itself cool. As the temperature rises, your body produces sweat to stay cool. On hot, humid days, the increased moisture in the air slows down this process. When your body can’t cool, your temperature rises, and you can become ill.

Hot weather and exercise are the main causes of heat exhaustion and heatstroke. In hot settings, you need to be mindful of the temperature outside. The heat index is not the same as the temperature. It measures the air temperature plus the effects of humidity. Prolonged exposure to high temperatures increases your risk of heat-related illnesses.

DIAGNOSIS

How are heat exhaustion and heatstroke diagnosed?

If a person is displaying known heat illness symptoms, take their temperature. A reading of 40°C (104°F) or more means they probably have heatstroke. You should call 911 and get medical care right away.

PREVENTION

How can I prevent heat illness?

There are many things you can do to prevent heat-related illnesses. Babies, children, and elderly people are more sensitive to heat and require extra attention. You also are at greater risk if you are ill or have obesity or heart disease. People who work outside or in a hot setting also are at risk of heat exhaustion and heatstroke.

Don’t go outside when the temperature and heat index are high. If possible, stay indoors in air-conditioned areas. If you must go outside, take the following precautions:

• Wear lightweight, light-colored, loose-fitting clothing.
• Protect yourself from the sun by wearing a hat or using an umbrella.
• Use sunscreen with a sun protection factor (SPF) of 30 or more.
• Drink plenty of water. throughout the day. Dehydration and lack of salt contribute to heat-related illnesses. Some sports drinks can help replenish the salt in your body lost through sweating. Drink water or other fluids every 15 to 20 minutes, even if you don’t feel thirsty. If your urine is clear, you are probably drinking enough fluids. Dark-colored urine is a sign that you’re dehydrated.
• Avoid or limit drinks that contain caffeine (such as tea, coffee, and soda) or alcohol.
• Schedule outdoor activities for cooler times of the day — before 10:00 a.m. and after 6:00 p.m.
• Take frequent breaks from the heat and outdoor activities.
• Do not stay or leave a child in your car when it is hot outside. Even if you open the windows, the intense heat can be extremely dangerous.

Certain medicines can put you in danger of heatstroke. They affect the way your body reacts to heat. Contact your healthcare provider if you take any of these or have an ongoing health problem. They can help you manage the heat with your condition. These medicines include:

• Antibiotics
• Allergy medicines (antihistamines)
• Some medicines used to manage blood pressure, cholesterol, and heart disease (beta-blockers and vasoconstrictors)
• Some medicines that treat mental health conditions (antidepressants and antipsychotics)
• Seizure medicines (anticonvulsants)
• Water pills (diuretics)
• Laxatives
• Some diet pills
• Prescription acne medicines
• Illegal drugs such as cocaine (amphetamines)

TREATMENT

If you think you or someone else has heat exhaustion, treat symptoms in the following ways.

• Get out of the heat quickly and into a cool place, or at least shade.
• Lie down and elevate your legs to get blood flowing to your heart.
• Take off any tight or extra clothing.
• Apply cool towels to your skin or take a cool bath. This will help regulate and lower your internal body temperature.
• Drink plenty of water or other fluids. Do NOT drink alcohol or caffeinated drinks (such as soda). These can make heat exhaustion worse.
• Drink fluids, such as water or a sports drink. Do not guzzle them but take sips. Do not drink fluids with caffeine or alcohol.

Seek emergency care:

• Symptoms don’t improve or they still have a fever of 102°F after 30 minutes of initial treatment.
• The person goes into shock, faints, or has seizures.
• The person is not breathing. You also should begin CPR right away to try and revive them.

Living with heat exhaustion and heat stroke

After you’ve had heat exhaustion or heatstroke, you will be sensitive to heat. This can last for about a week. It’s important to rest and let your body recover. Avoid hot weather and exercise. Ask your doctor when it’s safe to return to your normal activities.

This information provides a general overview and may not apply to everyone. Talk to your healthcare provider to find out if this information applies to you and to get more information on this subject.