How can you differentiate between heat stroke and heat exhaustion?

Reviewed by Yoshinori Abe, MD

Internal Medicine

Heat exhaustion and heat stroke are both heat-related illnesses, but they differ in severity. Heat exhaustion is the milder form, marked by heavy sweating, weakness, dizziness, nausea, and cool, clammy skin. Heat stroke is a medical emergency, characterized by a body temperature above 103°F, confusion, rapid pulse, and often hot, dry skin with little or no sweating.

Recognizing the difference matters—heat stroke can cause organ damage or death within minutes if untreated. If you're unsure which condition you or a loved one may be experiencing, don't guess. Take a free, instant, online symptom check to better understand your symptoms and confidently navigate your next steps.

Reviewed for medical accuracy: 07/14/2026

Important Next Steps

Learn if heat symptoms need urgent care Discover what may be causing your symptoms See if it could be heat stroke Find OTC relief for heat exhaustion symptoms Find a doctor for heat-related illness Understand medically valid heat exhaustion home remedies Find out how serious heat illness may be

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Explanation

When you have heat exhaustion, you might feel very tired, have a headache, feel dizzy, and your body sweats a lot. Your body temperature is usually only a little high. On the other hand, heat stroke is much more dangerous. With heat stroke, your body temperature is very high, and you may feel confused, have trouble speaking, or even lose consciousness. Here are some ways to tell them apart:

In Heat Exhaustion, you will usually notice:
Heavy sweating
Weakness and dizziness
A moderately raised body temperature
In Heat Stroke, you may see:
Very high body temperature
Confusion or strange behavior
Little to no sweating
Rapid breathing and a fast heartbeat

If you suspect heat stroke, it is important to get help immediately by calling emergency services. Cooling methods and fast treatment are needed to help prevent serious damage to your body. If you're experiencing any concerning symptoms and aren't sure whether you're dealing with heat exhaustion or something more serious, try Ubie's free AI-powered symptom checker to better understand what might be happening and what steps to take next.

(References)

Glazer JL. Management of heatstroke and heat exhaustion. Am Fam Physician. 2005 Jun 1;71(11):2133-40. PMID: 15952443.
Maule AL, Scatliffe-Carrion KD, Kotas KS, Smith JD, Ambrose JF. Heat exhaustion and heat stroke among active component members of the U.S. Armed Forces, 2019-2023. MSMR. 2024 Apr 20;31(4):3-8. PMID: 38722363; PMCID: PMC11107842.
Morris A, Patel G. Heat Stroke. [Updated 2023 Feb 13]. In: StatPearls [Internet].

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