--- title: "Heat Exhaustion vs Heat Stroke: How to Tell on the Job" description: "Heat exhaustion needs cooling and a medical check. Heat stroke is a 911 emergency. See symptoms side by side and first aid steps from OSHA and NIOSH." url: https://jmarsolutions.multisites.ai/guides/heat-exhaustion-vs-heat-stroke publisher: JMAR Solutions phone: +1-214-632-7780 quote: https://jmarsolutions.multisites.ai/contact --- Field guide # Heat exhaustion vs heat stroke: spot the difference fast Heat exhaustion is the body losing water and salt: heavy sweating, headache, nausea, dizziness, weakness. Heat stroke is worse: confusion, slurred speech, seizures or collapse. Heat stroke is a 911 emergency. Cool the worker, stay with them and call 911. OSHA says: when in doubt, cool the worker and call 911. Updated November 5, 20266 min read ## Heat stroke is a 911 call Confusion, slurred speech, seizures or collapse mean call 911 and cool the worker now. ## Do not diagnose OSHA says do not try to diagnose which illness is occurring. When in doubt, cool and call 911. ## Minutes matter NIOSH says body temperature can reach 106°F or higher within 10 to 15 minutes in heat stroke. ## Never leave them alone Stay with any worker who has heat symptoms until help takes over. ## What is the difference between heat exhaustion and heat stroke? Heat exhaustion is the body running low on water and salt. Heat stroke is the body failing to cool itself. NIOSH says heat exhaustion is “the body’s response to an excessive loss of water and salt, usually through excessive sweating.” Heat stroke is a 911 emergency. NIOSH calls heat stroke the most serious heat-related illness. It occurs “when the body can no longer control its temperature: the body’s temperature rises rapidly, the sweating mechanism fails, and the body is unable to cool down.” This guide is general safety information. It is not medical advice. Your site’s medical plan and local emergency services come first. If you think a worker has heat stroke, call 911 first. Then cool the worker. Do not wait to see if the worker feels better. ## How do the symptoms compare? Heat exhaustion looks like heavy sweating, headache and weakness. Heat stroke adds confusion, slurred speech, seizures or loss of consciousness. The lines can blur, so treat any worker with confusion as a possible heat stroke. Sign Heat exhaustion Heat stroke Mind Irritability Confusion, altered mental status, slurred speech Consciousness Dizziness, weakness Loss of consciousness (coma), seizures Skin and sweat Heavy sweating Hot, dry skin or profuse sweating Body temperature Elevated Very high; can reach 106°F or higher within 10 to 15 minutes Other signs Headache, nausea, thirst, decreased urine output Fatal if treatment is delayed What to do Medical evaluation, cool, sips of cool water Call 911, cool the worker fast, stay Source: NIOSH, Heat-related Illnesses. ## What are the signs of heat stroke? Look for confusion, slurred speech, collapse, seizures and very high body temperature. NIOSH lists these symptoms: confusion, altered mental status and slurred speech; loss of consciousness; hot, dry skin or profuse sweating; seizures; and very high body temperature. NIOSH also notes heat stroke is fatal if treatment is delayed. NIOSH says that in heat stroke “the body temperature can rise to 106°F or higher within 10 to 15 minutes.” It adds that heat stroke “can cause permanent disability or death if the person does not receive emergency treatment.” OSHA says heat stroke “requires immediate medical attention.” Read the [heat stroke](https://jmarsolutions.multisites.ai/glossary/heat-stroke) definition for a short form. ## What are the signs of heat exhaustion? Look for heavy sweating plus headache, nausea, dizziness, weakness, irritability, thirst, an elevated body temperature and less urine. NIOSH lists those symptoms. See the [heat exhaustion](https://jmarsolutions.multisites.ai/glossary/heat-exhaustion) definition. Heat exhaustion is not mild. OSHA says heat illness conditions can worsen quickly and result in fatalities. Take it seriously on every crew. ## What should you do for heat stroke? Call 911, cool the worker fast, and stay until emergency medical services arrive. NIOSH says “Call 911 for emergency medical care.” OSHA says “Confusion, slurred speech, or unconsciousness are signs of heat stroke.” Start cooling while you wait for help. 1. **Call 911.** Give the exact site address and gate. 2. **Stay with the worker.** NIOSH says to stay until emergency medical services arrive. 3. **Move the worker to a shaded, cool area** and remove outer clothing. 4. **Cool the worker quickly.** NIOSH lists a cold water or ice bath if possible, wetting the skin, cold wet cloths, and soaking clothing with cool water. 5. **Move air around the worker.** OSHA says to use fans to circulate air. 6. **Put cold wet cloths or ice on the head, neck, armpits and groin.** OSHA says “Never leave a worker with heat-related illness alone.” Do not give up cooling until the medical team takes over. ## What should you do for heat exhaustion? Get the worker out of the heat, cool them and get a medical evaluation. NIOSH says to take the worker to a clinic or emergency room for medical evaluation and treatment, and to call 911 if medical care is unavailable. Have someone stay with the worker until help arrives. NIOSH lists these steps: 1. Remove the worker from the hot area and give liquids to drink. 2. Remove unnecessary clothing, including shoes and socks. 3. Cool the worker with cold compresses, or have them wash the head, face and neck with cold water. 4. Encourage frequent sips of cool water. If the worker becomes confused, faints, has a seizure or cannot answer simply, treat it as heat stroke and call 911. ## Why should you not try to diagnose on site? Because symptoms overlap and time is short. OSHA says “Do not try to diagnose which illness is occurring.” It explains that diagnosis is often difficult because symptoms of multiple heat-related illnesses can occur together, and these conditions can worsen quickly. Then it gives the rule to follow: “When in doubt, cool the worker and call 911.” A supervisor’s job is not to name the illness. It is to start cooling, call for help and stay. Train every supervisor on that rule. Our [emergency protocol page](https://jmarsolutions.multisites.ai/resources/emergency-protocol) supports the training. ## What other heat illnesses look like NIOSH also lists heat cramps, heat syncope, heat rash and rhabdomyolysis. They are different problems with different first aid, and some need medical care. Illness Key signs Key point [Heat cramps](https://jmarsolutions.multisites.ai/glossary/heat-cramps) Muscle cramps, pain or spasms in the abdomen, arms or legs NIOSH says avoid salt tablets; get medical help for heart problems, a low sodium diet or cramps that last over 1 hour Heat syncope Short fainting, dizziness, lightheadedness on standing Sit or lie down in a cool place Heat rash Red clusters of pimples or small blisters Cooler, less humid area; keep dry [Rhabdomyolysis](https://jmarsolutions.multisites.ai/glossary/rhabdomyolysis) Muscle pain, dark urine, weakness Stop activity and seek immediate care NIOSH says rhabdo “causes the rapid breakdown, rupture, and death of muscle.” Dark, tea or cola-colored urine is a warning sign, so ask about it. Read our [heat illness pillar](https://jmarsolutions.multisites.ai/heat-illness) for more on recognizing each one. ## Who is at higher risk of heat illness on a crew? Anyone can get sick, but some workers face more risk. OSHA lists job risk factors: heavy physical activity, warm or hot conditions, lack of acclimatization, and clothing that holds in body heat. OSHA also lists personal risk factors: medical conditions, lack of physical fitness, previous heat illness, alcohol, drugs, and some medications. New workers come first on that list. OSHA says almost half of heat-related deaths occur on a worker’s first day on the job or first day back after an extended absence. Watch new and returning workers closely, and use a buddy system so no one works alone. ## What can a supervisor say in a 60-second huddle? Use plain words and repeat them every hot day: 1. “If you feel dizzy, sick, confused or weak, tell me or your buddy right away.” 2. “Watch each other. Confusion or slurred speech means call 911.” 3. “Heavy sweating, headache and nausea mean stop, cool down and get checked.” 4. “Drink often, even if you are not thirsty. Take every break.” 5. “I will stay with anyone who has symptoms. No one gets left alone.” These lines follow OSHA and NIOSH advice. For more scripts, see our [heat illness pillar](https://jmarsolutions.multisites.ai/heat-illness). ## How can employers lower the risk before anyone gets sick? Plan ahead with water, rest and shade, and ramp up new workers. OSHA says it “encourages water, rest, and shade as prevention as well as treatment for heat-related illness.” OSHA also says almost half of heat-related deaths happen on a worker’s first day on the job or first day back after an extended absence. Use the [heat acclimatization schedule](https://jmarsolutions.multisites.ai/guides/heat-acclimatization-schedule) and a written heat program. Keep cool water and a shaded rest area at the work, and practice the 911 call. Hydration supports the plan. OSHA says that on jobs longer than two hours, employers should provide electrolyte-containing beverages such as sports drinks. JMAR Solutions’ Rapid Restoration Drops are a dietary supplement that replaces electrolytes lost in sweat and supports hydration. JMAR says: “Rapid Restoration Drops are a safeguard, not a substitute for emergency care. In any suspected heat stroke or medical emergency, call 911 immediately.” See JMAR’s [hydration programs](https://jmarsolutions.multisites.ai/hydration-programs) for crew training. ## Next step Want a heat emergency plan your supervisors can follow? [Book a 15-minute demo](https://calendly.com/jen-jmarsolutions/15-min-meeting) with JMAR Solutions, or request a [free sample](https://jmarsolutions.multisites.ai/free-sample) for your next safety meeting. ## Frequently asked questions ### What is the difference between heat exhaustion and heat stroke? Heat exhaustion is the body's response to losing too much water and salt, mostly through sweat. Heat stroke is worse: the body can no longer control its temperature. Heat stroke can cause permanent disability or death without emergency treatment. Heat stroke is a 911 emergency. ### What are the signs of heat stroke at work? NIOSH lists confusion, altered mental status, slurred speech, loss of consciousness, hot dry skin or heavy sweating, seizures and very high body temperature. OSHA says confusion, slurred speech or unconsciousness are signs of heat stroke. Call 911 and cool the worker. ### What should I do for a worker with heat exhaustion? NIOSH says to take the worker to a clinic or emergency room for medical evaluation and treatment, call 911 if medical care is unavailable, and have someone stay with the worker. Move them out of the heat, give liquids, remove unnecessary clothing and cool them with cold compresses. ### Can heat exhaustion turn into heat stroke? Yes. OSHA says symptoms of multiple heat illnesses can occur together and that these conditions can worsen quickly. That is why OSHA says not to try to diagnose which illness is occurring. Cool the worker and call 911 when in doubt. ### Do electrolyte drops treat heat stroke? No. Nothing in this guide treats heat stroke except emergency care and rapid cooling. JMAR Solutions says its drops are a safeguard, not a substitute for emergency care, and says to call 911 immediately for any suspected heat stroke or medical emergency. ## Terms on this page - [Acclimatization](https://jmarsolutions.multisites.ai/glossary/acclimatization) - [Heat exhaustion](https://jmarsolutions.multisites.ai/glossary/heat-exhaustion) - [Rhabdomyolysis](https://jmarsolutions.multisites.ai/glossary/rhabdomyolysis) - [Buddy system](https://jmarsolutions.multisites.ai/glossary/buddy-system) - [Electrolyte](https://jmarsolutions.multisites.ai/glossary/electrolyte) - [Heat cramps](https://jmarsolutions.multisites.ai/glossary/heat-cramps) - [Heat stroke](https://jmarsolutions.multisites.ai/glossary/heat-stroke) - [Heat rash](https://jmarsolutions.multisites.ai/glossary/heat-rash) - [Hydration](https://jmarsolutions.multisites.ai/glossary/hydration) - [Sodium](https://jmarsolutions.multisites.ai/glossary/sodium) ## 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) 3. [CDC/NIOSH: Heat-related illnesses](https://www.cdc.gov/niosh/heat-stress/about/illnesses.html) 4. [CDC/NIOSH: Heat-related illnesses](https://www.cdc.gov/niosh/heat-stress/about/illnesses.html) 5. [CDC/NIOSH: Heat-related illnesses](https://www.cdc.gov/niosh/heat-stress/about/illnesses.html) 6. [CDC/NIOSH: Heat-related illnesses](https://www.cdc.gov/niosh/heat-stress/about/illnesses.html) 7. [CDC/NIOSH: Heat-related illnesses](https://www.cdc.gov/niosh/heat-stress/about/illnesses.html) 8. [CDC/NIOSH: Heat-related illnesses](https://www.cdc.gov/niosh/heat-stress/about/illnesses.html) 9. [CDC/NIOSH: Heat-related illnesses](https://www.cdc.gov/niosh/heat-stress/about/illnesses.html) 10. [CDC/NIOSH: Heat-related illnesses](https://www.cdc.gov/niosh/heat-stress/about/illnesses.html) 11. [CDC/NIOSH: Heat-related illnesses](https://www.cdc.gov/niosh/heat-stress/about/illnesses.html) 12. [CDC/NIOSH: Heat-related illnesses](https://www.cdc.gov/niosh/heat-stress/about/illnesses.html) 13. [CDC/NIOSH: Heat-related illnesses](https://www.cdc.gov/niosh/heat-stress/about/illnesses.html) 14. [CDC/NIOSH: Heat-related illnesses](https://www.cdc.gov/niosh/heat-stress/about/illnesses.html) 15. [CDC/NIOSH: Heat-related illnesses](https://www.cdc.gov/niosh/heat-stress/about/illnesses.html) 16. [CDC/NIOSH: Heat-related illnesses](https://www.cdc.gov/niosh/heat-stress/about/illnesses.html) 17. [CDC/NIOSH: Heat-related illnesses](https://www.cdc.gov/niosh/heat-stress/about/illnesses.html) 18. [CDC/NIOSH: Heat-related illnesses](https://www.cdc.gov/niosh/heat-stress/about/illnesses.html) 19. [CDC/NIOSH: Heat-related illnesses](https://www.cdc.gov/niosh/heat-stress/about/illnesses.html) 20. [CDC/NIOSH: Heat-related illnesses](https://www.cdc.gov/niosh/heat-stress/about/illnesses.html) 21. [CDC/NIOSH: Heat-related illnesses](https://www.cdc.gov/niosh/heat-stress/about/illnesses.html) 22. [CDC/NIOSH: Heat-related illnesses](https://www.cdc.gov/niosh/heat-stress/about/illnesses.html) 23. [CDC/NIOSH: Heat-related illnesses](https://www.cdc.gov/niosh/heat-stress/about/illnesses.html) 24. [CDC/NIOSH: Heat-related illnesses](https://www.cdc.gov/niosh/heat-stress/about/illnesses.html) 25. [CDC/NIOSH: Heat-related illnesses](https://www.cdc.gov/niosh/heat-stress/about/illnesses.html) 26. [CDC/NIOSH: Heat-related illnesses](https://www.cdc.gov/niosh/heat-stress/about/illnesses.html) 27. [OSHA: Heat overview, working in outdoor and indoor heat environments](https://www.osha.gov/heat-exposure) 28. [OSHA: Heat-related illnesses and first aid](https://www.osha.gov/heat-exposure/illness-first-aid) 29. [OSHA: Heat-related illnesses and first aid](https://www.osha.gov/heat-exposure/illness-first-aid) 30. [OSHA: Heat-related illnesses and first aid](https://www.osha.gov/heat-exposure/illness-first-aid) 31. [OSHA: Heat-related illnesses and first aid](https://www.osha.gov/heat-exposure/illness-first-aid) 32. [OSHA: Heat-related illnesses and first aid](https://www.osha.gov/heat-exposure/illness-first-aid) 33. [OSHA: Heat-related illnesses and first aid](https://www.osha.gov/heat-exposure/illness-first-aid) 34. [OSHA: Heat-related illnesses and first aid](https://www.osha.gov/heat-exposure/illness-first-aid) 35. [OSHA: Water. Rest. Shade.](https://www.osha.gov/heat-exposure/water-rest-shade) 36. [OSHA: Heat overview, working in outdoor and indoor heat environments](https://www.osha.gov/heat-exposure) 37. [OSHA: Protecting new workers from heat](https://www.osha.gov/heat-exposure/protecting-new-workers) 38. [OSHA: Heat overview, working in outdoor and indoor heat environments](https://www.osha.gov/heat-exposure) Checked against the sources above on November 5, 2026. Rules and guidance change, so check the linked page before you act. This page is general information, not legal or medical advice. ## Keep reading - [Heat illness: signs, first aid and when to call 911Heat stroke is an emergency. Call 911, stay with the worker, move them to shade and cool them fast. NIOSH says body temperature can reach 106°F within 10 to 15 minutes. Heat exhaustion needs medical evaluation. Heat cramps, heat rash, fainting and rhabdo each have their own signs and steps. Know them before the shift.](https://jmarsolutions.multisites.ai/heat-illness) - [A heat acclimatization schedule for new and returning workersNIOSH says to build heat tolerance over 7 to 14 days. New workers do no more than 20% of the usual time in the heat on day 1, then add no more than 20% each day. Experienced workers can do 50%, 60%, 80%, then 100% on days 1 through 4. Cut the time, not the work intensity.](https://jmarsolutions.multisites.ai/guides/heat-acclimatization-schedule) - [Heat stress prevention for high-risk crewsHeat stress prevention starts with water, rest and shade, then adds acclimatization for new workers, supervisor training and a written plan. NIOSH says to give workers cool water near the work area and to build up heat exposure over 7 to 14 days. Electrolytes support hydration when a crew sweats for hours.](https://jmarsolutions.multisites.ai/heat-stress-prevention) - [A 5-minute heat toolbox talk, word for wordA heat toolbox talk is a short crew meeting before work that covers the signs of heat illness, how often to drink, who watches whom, and when to call 911. This guide gives a word-for-word script that takes about five minutes, built on NIOSH training guidance, plus a sign-off sheet.](https://jmarsolutions.multisites.ai/guides/heat-toolbox-talk) - [3 Early Signs of Heat Illness Crews Often MissThree early signs crews miss are dark or low urine, headache with irritability, and muscle cramps. NIOSH lists decreased urine output, headache, and irritability as heat exhaustion symptoms, and tea or cola-colored urine as a sign of rhabdomyolysis. Act on these signs early. Heat stroke is a 911 emergency.](https://jmarsolutions.multisites.ai/blog/early-signs-of-heat-illness-crews-miss) - [Build a heat stress program in 8 stepsA heat stress program has eight parts: name a daily lead, measure heat on site, set advisory-day triggers, give water, rest and shade, acclimatize workers, train everyone, plan first aid and 911, then review. OSHA says employers should write the plan down. This follows OSHA and NIOSH guidance, not a final federal rule.](https://jmarsolutions.multisites.ai/guides/heat-stress-program-for-employers) ![Ironworkers silhouetted on a steel frame against a hot orange sunset](https://jmarsolutions.multisites.ai/_astro/sunset-steel.IhAMDca0_6wk53.webp) ## See it on your crew in 15 minutes Jennifer walks your safety team through the drops, the protocol and the numbers on a short live call. [Book a 15-minute demo](https://calendly.com/jen-jmarsolutions/15-min-meeting)