---
title: "What Is Heat Exhaustion? Heat Stress and Hydration Glossary"
description: "Heat exhaustion is the body's response to losing too much water and salt, usually through heavy sweating."
url: https://jmarsolutions.multisites.ai/glossary/heat-exhaustion
publisher: JMAR Solutions
phone: +1-214-632-7780
quote: https://jmarsolutions.multisites.ai/contact
---

Heat illness

# Heat exhaustion

Heat exhaustion is the body's response to losing too much water and salt, usually through heavy sweating. Signs include headache, nausea, dizziness, weakness and heavy sweating.

Heat exhaustion comes from losing too much water and salt through sweat. NIOSH lists headache, nausea, dizziness, weakness, irritability, thirst and heavy sweating as signs.

Move the worker out of the heat, give cool sips of water, and cool the head, face and neck with cold water. NIOSH says to take the worker to a clinic or emergency room for medical evaluation. Call 911 if medical care is unavailable. Do not wait. Heat exhaustion can turn into [heat stroke](https://jmarsolutions.multisites.ai/glossary/heat-stroke), which is always a 911 emergency. [Heat cramps](https://jmarsolutions.multisites.ai/glossary/heat-cramps) can be an early sign. See our [heat exhaustion vs heat stroke guide](https://jmarsolutions.multisites.ai/guides/heat-exhaustion-vs-heat-stroke).

[From JMAR SolutionsHydration programs and toolbox talks for crews](https://jmarsolutions.multisites.ai/hydration-programs)

## Related terms

-   [Heat stroke](https://jmarsolutions.multisites.ai/glossary/heat-stroke)
-   [Heat cramps](https://jmarsolutions.multisites.ai/glossary/heat-cramps)
-   [Heat stress](https://jmarsolutions.multisites.ai/glossary/heat-stress)
-   [Electrolyte](https://jmarsolutions.multisites.ai/glossary/electrolyte)

## Sources

1.  [CDC NIOSH: Heat-related Illnesses](https://www.cdc.gov/niosh/heat-stress/about/illnesses.html)
2.  [CDC NIOSH: Heat-related Illnesses](https://www.cdc.gov/niosh/heat-stress/about/illnesses.html)

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