7 Heat-Related Illnesses: Causes, Prevention, and Treatment

• Heat illnesses occur when our body cannot function as usual due to extreme heat or prolonged exposure to heat.
• There are seven main types of heat illness. Some types of heat illness, such as heat stroke or heat syncope, can be serious, requiring immediate medical attention.
• These illnesses can be prevented through actions like spending time in a cooler space, staying hydrated, and wearing sunscreen. 

Hot weather brings to mind sun-kissed skin, picnics with friends, and enjoying cool treats, like ice cream or fresh fruit. Yet warm weather also brings the potential for heat illnesses, a group of medical conditions that stem from the body’s inability to regulate body temperature due to extreme heat and/​or prolonged exposure to it. 

Heat illnesses can be quite serious; they account for 0.4 per 100,000 deaths annually in the US, with those over 55 experiencing more severe symptoms and a higher risk of death or severe complications. To help stay cool the next time a heat wave strikes, try these prevention tactics and learn the warning signs of the seven most common heat-related illnesses.

When it’s hot outside, our bodies naturally cool down by sweating. During extremely hot weather or if we spend too long in the heat, sweating sometimes isn’t enough, and the body struggles to regulate core body temperature. As our body’s response to heat becomes less robust, there’s an increased risk of heat illnesses, a group of different conditions that negatively impact health.

Heat illness is actually an umbrella term for any medical condition that occurs due to extreme heat exposure. The seven below are the most common, each with its own unique symptoms and treatments.

Heat Cramps

Heat cramps, muscle pains or spasms, often affect those who complete strenuous activity, such as lifting something heavy or walking for a long time, in a hot, humid environment. They often occur in the abdomen, hands, arms, legs, feet, and shoulders. First aid for heat cramps includes drinking water, avoiding salt tablets, and an ice bath for those who don’t have heart conditions. 

Heat cramps do not typically require immediate medical help, though a trip to the emergency department may be merited if the person experiencing heat cramps has any heart conditions or is on a low-sodium diet. Additionally, the Centers for Disease Control recommends seeking medical attention if the cramps don’t go away within one hour. 

Heat Exhaustion

Hot weather can lead to excessive sweating. Since sweat is made up of water and salt, heat may lead to an extreme loss of both. Should this occur, someone may be diagnosed with heat exhaustion.

Common symptoms include:

• Headache
• Nausea
• Dizziness
• Weakness
• Extreme thirst
• Overactive sweat glands
• Elevated body temperature
• Difficulty urinating or a decrease in urine output

Heat exhaustion is considered an immediate medical emergency, requiring a call to 911 or a prompt visit to a healthcare provider. While waiting for medical care, appropriate first aid includes removing unnecessary clothing, having someone stay with the person experiencing heat exhaustion, and applying a cold compress to the face and/​or neck. 

Heat Rash

If the skin becomes red and irritated during heat waves, someone may be diagnosed with a heat rash, also known as prickly heat. A heat rash usually looks like a small cluster of red bumps or pimples, typically appearing on the upper chest, neck, elbow creases, or groin. Heat rash is often due to the friction caused by heavy sweating in hotter weather. 

First aid for a heat rash includes keeping the rash area dry and spending time in a cooler, less humid environment when possible. 

Heat Stroke

Heat stroke, the most serious heat-related illness, occurs when the body’s ability to regulate heat fails. During a heat stroke, someone’s body temperature rises rapidly, sweat glands don’t work properly, and the body’s ability to cool itself down fails. The body’s temperature can rise to 106°F or higher, often within 10 to 15 minutes.

Symptoms of heat stroke include:

• Seizures
• Confusion or altered mental capabilities
• Slurred speech
• Hot, dry skin
• Very high body temperature
• Entering a coma, a state marked by a loss of consciousness

A heat stroke can occur from physical activity in the heat, referred to as exertional heat stroke, or from simply being in the heat too long, referred to as a classic or non-exertional heat stroke. Either requires immediate medical care. While waiting for medical attention to arrive, move the affected individual to shade or a cooler area, offer a cold compress for their neck or head, and remove any unnecessary clothing. 

Heat Syncope

Heat syncope is when someone faints or feels dizzy due to hot weather. Usually, it occurs when someone has stood in the heat for too long or when standing up after sitting or lying down. It is most common in those who are unfamiliar with being in a hot environment or who aren’t hydrated. Usually, rest and hydration can treat heat syncope, but severe cases, such as fainting and not getting up quickly, may require emergency medical attention. 

Rhabdomyolysis

When someone physically exerts themselves and experiences heat stress at the same time, they may suffer from rhabdomyolysis, rapid muscle breakdown. As muscles break down, muscle tissue dies, releasing electrolytes and other proteins into the bloodstream. Because this release is rapid, it may cause:

• Muscle cramps
• Dark urine
• Weakness
• Inability to exercise

In severe cases, it may also lead to an irregular heart rhythm and a higher chance of kidney disease or a seizure. In other cases, rhabdomyolysis can present no symptoms. When severe symptoms are present, seek immediate medical attention. While waiting on medical attention, the affected individual should head to a cooler environment, apply a cold compress on the skin, and remove unnecessary outer clothing. 

Sun Exposure

Sun exposure, commonly called sunburn, can occur in any type of weather, though it is more common in hotter climates. This condition occurs when the skin is exposed to extreme or prolonged sunlight, first manifesting as red and tender skin. If severe, skin may start to peel, burns may develop blisters, and affected areas can be hot to the touch. 

To treat sunburn, keep skin cool, apply a cooling ointment like aloe vera, stay hydrated, and use sunscreen and appropriate clothing to prevent future damage.

Signs of Heat-Related Health Problems

While the six illnesses above all manifest in different ways, there are some tell-tale signs that someone may be developing or suffering from a heat-related illness:

• Dizziness or lightheadedness
• Confusion
• Muscle weakness or cramps
• Profuse sweating
• Dry mouth or thirst
• Red, irritated, or dry skin
• Higher body temperature

If any of these signs are present, trying at-home treatment or seeking medical care is a good way to prevent complications.

While anyone in a hot environment may get a heat illness, some people are more susceptible due to physiological factors or their age. Individuals at a higher risk for heat illnesses include:

• Younger children
• Older adults
• Pregnant people
• Being an athlete who works out outdoors
• Those working outside, especially in a physically demanding role
• Individuals with an active viral infection, like a cold or the flu
• People with cardiovascular disease, diabetes, asthma, or another chronic medical condition that increases the risk of heat illnesses
• Those who are dehydrated or have recently experienced extreme fluid loss (i.e., via sweating)
• People taking certain medications, including diuretics and some blood pressure or heart medications.

There are also some environmental factors that can increase the risk of heat-related illnesses:

• Living in a place without air conditioning
• Hot and humid weather
• Long periods of heat exposure (i.e., spending all day outside when it’s hot)

Regardless of someone’s risk level for heat illness, they can take some prevention steps. The first step is: pay attention to the weather, noting days when it could be dangerous to stay out for long periods. Local news stations often broadcast when there’s a heat alert, as do heat health warning systems, like the one from the CDC. This heat tracker documents areas in the nation experiencing extreme heat, projected temperatures in different regions as climate change progresses, and a one-month forecast for each state.

Other steps to reduce exposure during a heat wave include:

• Spend as much time in cooler areas as possible: If living in a space without AC, consider investing in a fan or smaller AC unit or visiting public spaces with AC, such as a library or community center.
• Take a cool shower: When hot, it’s better to shower with cool water than hot water.
• Stay hydrated: Drink cold water or ice water as much as possible. The recommended daily water intake actually varies based on someone’s sex, activity level, age, and environment. When the climate is hot, the recommended amount of water increases.
• Dress for the occasion: Remove unnecessary clothing or dress in lighter fabrics when it’s hot outside.
• Avoid or limit alcohol and caffeine: Caffeine and alcohol both dehydrate the body, so they are best enjoyed in moderation or avoided entirely when the weather is hot. Instead, opt for a juice or water.
• Exercise indoors: When the weather is very hot, work out indoors. This could mean doing that daily walk at the shopping center instead of the park, or registering for a workout class in an air-conditioned gym or studio.
• Use sunscreen: Use SPF 15 or higher on exposed body parts to reduce the risk of sunburn. Hats, sunglasses, and other protective clothing can help too. 

When experiencing signs of heat-related illnesses, head to a cool place, drink fluids, and cool off with a shower or ice pack. It may also be beneficial to assess if a trip to the emergency room is necessary, as it often is for heat stroke or when more severe symptoms are present, such as ongoing dizziness or slurred speech.

Once in a medical facility, a doctor can prescribe the right course of treatment, which varies depending on the severity of the illness. Common medical treatments can include:

• Resting in a cool space 
• Hydrating
• IV infusions with electrolytes 
• Seizure treatments, such as anti-seizure medications and surgery on affected parts of the brain

Throughout treatment, healthcare providers and loved ones can encourage frequent sips of water as this helps with recovery.