Heat exhaustion symptoms: A road worker passed out on the street on a hot day

You’re out being active on a bright, sunny day and suddenly you’re overwhelmed by the heat. You start to feel like your body can’t cool down, your face is flushed, and your mouth is parched. Your muscles start to cramp and you feel like you might faint. You may be suffering from heat exhaustion. 

While heat exhaustion tends to be mild to moderate, symptoms can progress to a more dangerous condition called heat stroke. Here, we’ll explain heat exhaustion symptoms to watch out for, how to know when to seek medical advice, and what you can do to ease symptoms.

Heat Exhaustion Symptoms

Heat exhaustion symptoms: A hiker feels faint in the heat

Heat exhaustion is a heat-related illness and some of the main signs of heat exhaustion include changes in body temperature and dehydration. The excessive heat can cause heat stress and lead to symptoms including headaches and nausea along with difficulty breathing and feeling faint. Here are some of the symptoms of heat exhaustion:

  • Muscle Cramps
  • Heavy Sweating
  • Dehydration
  • Nausea
  • Fainting
  • Diarrhea
  • Dizziness
  • Pale, cool, and clammy skin with goosebumps
  • Rapid, weak pulse
  • Fatigue and anxiety
  • Core body temperature higher than 100.4°F

The Difference Between Heat Exhaustion and Heatstroke

Heat exhaustion symptoms: An athlete holds her hand to her forehead in the heat

Heat exhaustion and heat stroke are both heat illnesses that occur on a spectrum according to the CDC. The most minor heat illness is known as heat rash. This condition typically involves red blisters or itchy red patches on the elbows, knees, chest, and groin. It can be treated by moving to a cool place and applying baby powder to soothe skin irritation.

Next on the heat illness spectrum is sunburn. Symptoms of sunburn include skin blisters and red skin. Prevention and treatment consist of wearing sunscreen with an SPF of 15 or higher, applying aloe, and staying out of the sun. Heat cramps can also develop, causing your muscles to become tight due to dehydration. 

The next level of heat illness is heat exhaustion, followed by heatstroke. Heatstroke is the most serious heat-related illness and often requires medical attention. Severe cases of heatstroke can result in brain damage and even death. Symptoms of heatstroke that aren’t associated with heat exhaustion include:

  • Loss of consciousness
  • Pounding headache
  • Rapid, strong pulse
  • Vomiting
  • Hot, dry skin
  • Lack of sweat
  • Changes in demeanor including confusion, agitation, and numbness
  • Internal body temperature or fever higher than 104°F

Causes of Heat Exhaustion

Heat exhaustion symptoms: A heat warning sign in a desert environment

Heat exhaustion is caused by changes in body temperature. The normal core temperature of the human body is 98.6 degrees Fahrenheit. Core temperature, or internal temperature, is the measurement of your body’s temperature as it adjusts to outside temperatures. The human body moves blood closer to internal organs to compensate for cooler outdoor temperatures and uses sweating to decrease its internal temperature in hot weather.

When your body is unable to regulate its normal core temperature, you can develop heat-related illnesses. The main cause of heat exhaustion is the inability of your body to effectively cool itself down. This can occur if you are active in hot weather without drinking enough fluids. High humidity can also limit the ability of your body to cool itself off through sweat. That’s because moist, wet air doesn’t absorb body sweat into the atmosphere as effectively as dry air.

Dehydration, alcohol consumption, and overdressing can also cause heat exhaustion. Dehydration is a condition where the body doesn’t get enough fluids, resulting in a poor ability to produce sweat and cool off. Drinking alcohol can increase the risk of dehydration and limits your body’s ability to sweat and control body temperature.

Wearing the wrong clothes can also increase your risk of heat exhaustion. Avoid wearing tight clothes as they don't allow for proper airflow and can minimize the body’s ability to sweat. Skip thick fabrics, especially if it’s hot out. Take off extra articles of clothing if you start to heat up while exercising.

Risk Factors of Heat Exhaustion

While anyone can suffer from heat exhaustion, there are certain risk factors that can increase the likelihood of developing a heat-related illness. Certain medical conditions, medications, and external factors can increase sensitivity to heat. Here are some of the main risk factors of heat exhaustion.

  • Age: Children under the age of four years old aren’t able to regulate their temperatures as well as adults since they’re still developing. Kids can also develop dehydration more easily. Elderly people over 65 years old have a higher risk of developing heat exhaustion due to health changes and deterioration in overall health.
  • Medications: Many medications have side effects including dehydration that can directly affect the body’s ability to regulate temperature. Common culprits include blood pressure and heart disease medications such as beta-blockers and diuretics. Antihistamines for allergy symptoms, sedatives, and antidepressants can also increase the risk of heat exhaustion.
  • Overall health: Certain health conditions, including obesity, can increase the risk of heat exhaustion. The excess weight makes it more difficult for your body to sweat and cool down.
  • Heat index: The heat index combines the outdoor temperature with the humidity levels. The body is less effective at controlling its internal temperature when the humidity and heat are higher. When the heat index is at 91 degrees Fahrenheit or higher, the risk of heat exhaustion dramatically increases.

How To Treat Symptoms of Dehydration From Heat Exhaustion

Heat exhaustion symptoms: A pouch of orange flavored oral rehydration solution

Treatment of heat exhaustion typically involves simple first aid. As the temperature rises, move to a cooler location in the shade or inside where there is air conditioning. Take off any extra articles of clothing and use a fan to help cool yourself down. You can also jump into cool water such as a lake or river or take a cool bath at home.

For dehydration, drink plenty of fluids, starting with an oral rehydration solution (ORS), like DripDrop ORS. This solution contains a precise mixture of electrolytes and vitamins like potassium, sodium, and glucose. These ingredients can help replenish minerals that are lost during excessive sweating and can help reverse dehydration faster and more effectively than water or sports drinks.

If heat exhaustion is left untreated, you may develop symptoms of heatstroke. Heatstroke is a serious condition and should be treated as a medical emergency. Seek medical attention at the first warning signs, especially if you have a high fever. 

If you suffer from this heat emergency, call 911, and follow the medical advice of first responders. Try to get to a cool location and place ice packs under your armpits or by your groin. These areas of the body have large blood vessels that can cool the body more quickly than when placing ice elsewhere.

Prevent Heat Exhaustion With These Tips

Heat exhaustion is preventable. Lifestyle changes and drinking fluids rich in electrolytes like an oral rehydration solution are two of the easiest ways to avoid dehydration from heat exhaustion. 

Avoid exercising in high temperatures and extreme heat, especially when the heat index is above 91 degrees Fahrenheit. If there’s a heatwave, move your activities indoors or to a gym where there is air conditioning. 

Plan your physical activity in cooler locations such as on shaded trails or alongside rivers. Avoid strenuous activity in hot environments and try working outside during the cooler hours of the day, including early mornings and late evenings.

Increase your fluid intake and make sure to choose drinks like DripDrop ORS that contain sodium and glucose that your body loses through sweat to prevent dehydration.