Heat-Related Illness: Heat Rash, Heat Exhaustion, Heat Stroke and More

Sunny days can be inviting, but extreme heat can quickly turn dangerous. In addition to sunburn and increased skin cancer risk, high temperatures can overwhelm the body’s ability to regulate itself. This can lead to a variety of heat-related illnesses. 

As temperatures continue to rise across the United States, so do the risks. According to the Centers for Disease Control and Prevention (CDC), heat-related illnesses are sending more people to the emergency room than ever before. The National Oceanic and Atmospheric Administration confirmed summer 2025 was the hottest on record. The CDC reports that extreme heat is now the deadliest weather-related hazard in the country. 

“People are ending up in the hospital now and even experiencing long-term effects from what can be a one-time heat event,” said Michael Sousa-Johnson, MS, LAT, ATC, athletic trainer with Covenant Health Sports Medicine, stationed at Cumberland County High School. “In some extreme cases, it can even lead to death.” 

Understanding the different types of heat illness and how to respond can help keep you and your loved ones safe this summer. 

What Are Heat-Related Illnesses? 

Heat-related illnesses occur when the body cannot cool itself effectively. High temperatures, especially when combined with humidity, can lead to conditions ranging from mild discomfort to life-threatening emergencies. 

According to the Tennessee Department of Health, more than 2,000 Tennesseans require emergency care for heat-related illness each year. Most cases occur between May and September, but longer and more intense heat waves are increasing both the frequency and severity of cases. 

“There’s really a spectrum when it comes to heat illness,” Sousa-Johnson said. “There isn’t a hard line between stages. Things can go from bad to worse within minutes if they’re not recognized and managed.” 

Who Is Most at Risk? 

Anyone can experience a heat-related illness, but some groups are more vulnerable: 

• Children younger than 4 

• Adults 65 and older 

• Pregnant women 

• People with chronic conditions such as diabetes, heart disease or kidney disease 

• Individuals who are overweight 

• People recovering from illness 

• Outdoor workers and athletes 

• People without access to cooling or shelter 

Alcohol use, certain medications and lack of heat acclimation can also increase risk. 

Early Warning Signs to Watch For 

Heat illness often begins with mild symptoms that can quickly worsen if ignored. Early warning signs include: 

• Headache 

• Dizziness 

• Heavy sweating 

• Shortness of breath 

• Intense thirst 

“These are the body’s early signals,” Sousa-Johnson said. “Most of the time, they can be managed with rest, shade and water. Ignoring them is where people get into trouble.” 

Humidity makes the body feel hotter by preventing sweat from evaporating. When sweat cannot evaporate, heat is trapped in the body. Make sure to take extra precautions on humid days. 

Common Heat-Related Illnesses 

Heat cramps 

Heat cramps are often caused by fluid and electrolyte loss due to sweating. Symptoms may include muscle cramps, pain and cool, moist skin. Treatment includes rest, hydration and electrolyte replacement. “Hydration starts well before you ever go outside,” Sousa-Johnson said. “If you’re not drinking enough ahead of time, you’re already behind.” 

Heat syncope 

Heat syncope is fainting after prolonged heat exposure. Symptoms include dizziness, lightheadedness and fainting. Treatment includes sitting or lying down and slowly rehydrating. 

Heat rash 

Heat rash occurs when sweat becomes trapped in the skin. Symptoms include red or itchy skin and small bumps. Treatment includes keeping the skin cool and dry. 

Heat exhaustion 

Heat exhaustion happens when the body loses too much water and salt. Symptoms include heavy sweating, fatigue, nausea, headache and dizziness. “People with heat exhaustion may stop making sense when they talk,” Sousa-Johnson said. Treatment includes cooling down, removing excess clothing and drinking fluids. 

Heat stroke 

Heat stroke is a medical emergency. Symptoms include confusion, unconsciousness, hot dry skin and a body temperature above 105 degrees Fahrenheit. “If someone becomes unconscious, stops sweating or feels hot and dry, that is a major red flag,” Sousa-Johnson said.  

If you believe you or someone else is experiencing heat stroke, seek medical attention immediately. Until you can be seen by a medical professional, move to a shaded or cool area and remove unnecessary layers of clothing. Use a cold compress or a cold, wet cloth to lower body temperature. 

Heat Safety Tips 

Hot weather can take a serious toll on the body, especially during physical activity. Dehydration and heat-related illnesses can develop quickly, but they’re also completely preventable with the right habits. Understanding when to hydrate, when to rest and how to recognize early warning signs can help you stay safe and perform your best in the heat. 

Avoid common heat mistakes such as: 

• Not drinking enough water 

• Skipping breaks 

• Exercising during peak heat 

• Ignoring symptoms 

Stay hydrated by: 

• Drinking plenty of water before activity 

• Continuing to drink water consistently during activity 

• Using electrolytes during longer outdoor activities 

To stay safe in the summer heat, Sousa-Johnson also suggests: 

• Having somewhere shady to rest  

• Keeping plenty of cold water available 

• Stopping to rest when you notice symptoms of exertional heat illness 

He further explained, “Heat illness has cumulative effects. It’s not here one day and gone the next. If you don’t get back to a normally hydrated state, you’ll end up right back where you were the day before. Heat-related illnesses are 100% preventable, it just takes knowing what to look for.” 

When to Contact a Health Provider 

If you think you or someone else is experiencing heat stroke, call 911 or go to the nearest emergency room. If symptoms of heat exhaustion last more than 30 minutes, seek emergency care to make sure it’s not a heat stroke.  

Covenant Health’s hospital emergency departments are open 24/7 throughout East Tennessee. Other heat illnesses like heat rash and heat cramps don’t usually require medical attention, but consult a provider if symptoms do not go away after home treatment.