Heat exhaustion vs. heat stroke: Know the Signs

Updated: July 29, 2026

Hot, humid summer days can quickly take a toll on your body, especially when you're spending extended time outdoors, exercising or doing strenuous activities.

Heat-related illness can begin with relatively mild symptoms and become serious if you don't cool down and rehydrate. Knowing the difference between heat cramps, heat exhaustion and heat stroke, can help you recognize the warning signs early and know when emergency help is needed.

In the video below, Dr. Ryan Bird, Medical Director of Emergency Medicine at Touro, explains the signs of heat-related illness, what to do when symptoms begin and how to prepare for extreme heat.

Heat cramps: an early warning sign

Heat cramps can be one of the first signs that your body is struggling in the heat. They often cause painful muscle cramps or spasms, particularly during or after physical activity. 

If heat cramps develop:

• Stop your activity and move to a cool air-conditioned place
• Rest and allow your body to cool down
• Drink water or a sports drink to replace fluids
• Avoid returning to strenuous activity until the cramps have resolved

Paying attention to these early symptoms can help prevent heat illness from progessing.

What does heat exhaustion feel like?

Heat exhaustion occurs when the body becomes overheated and can no longer keep up with the heat and fluid loss.

Signs may include:

• Heavy sweating
• Cool, pale, or clammy skin
• Muscle cramps
• Weakness or fatigue
• Headache or dizziness
• Nausea or vomiting
• Fainting

If you think you may be experiencing heat exhaustion, move indoors or to a cooler area, loosen tight clothing and use cool, wet cloths or a cool shower to help lower your body temperature. Sip water and give yourself time to rest and recover.

Seek medical attention if you're vomiting, your symptoms are getting worse, or they do not improve after cooling down and rehydrating.

When heat illness becomes an emergency

Heat stroke is the most serious form of heat-related illness and requires immediate medical attention.

Warning signs can include:

• A body temperature of 103°F or higher
• Hot, red skin that may be dry or damp
• Confusion or unusual behavior
• Severe dizziness
• A strong, rapid pulse
• Loss of consciousness
• Seizures

If heat stroke is suspected, call 911 immediately.

While waiting for emergency medical help, move the person to a cooler area and begin cooling them with cool, wet cloths, or a cool bath or other available cooling methods.

How to prepare for extreme heat

The best way to manage heat-related illness is to prevent it in the first place.

Before spending time outdoors:

• Check for extreme heat warnings
• Drink fluids before heading outside and continue hydrating throughout the day
• Wear lightweight, loose-fitting clothing
• Take frequent breaks in the shade or air conditioning
• Avoid strenuous outdoor activity during the hottest parts of the day when possible
• Pay attention to early symptoms instead of trying to push through them

And never leave a child or pet unattended in a parked vehicle, even for a short period of time.

Listen to your body

Heat-related illness can progress quickly. If you begin experiencing cramps, dizziness, weakness, nausea or other symptoms while in the heat, stop what you're doing, get somewhere cool and begin rehydrating.

Recognizing the signs early can help heat exhaustion from becoming a life-threatening emergency. 

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