Compare conditions

Put any two — or three — conditions side by side, adult or pediatric, to spot the look-alike differences fast, row by row.

Heat Illness and Hypothermia

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In one line

·When body temperature climbs above 40°C (104°F), the brain and organs start to cook and fail; when it drops below 35°C (95°F), the heart slows dangerously and blood chemistry falls apart.

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Normal physiology

·The hypothalamus (your brain's thermostat, sitting just above the brainstem) constantly measures blood temperature and defends a core setpoint of 37°C by balancing heat production (from muscles and metabolism) with heat loss (through skin blood flow, sweat, and breathing).

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What goes wrong

·The thermostat loses the fight when outside heat (or cold) is too extreme, when your muscles make heat faster than sweat can dump it, when you're dehydrated and can't sweat, or when drugs or illness jam the hypothalamus signals.

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Hallmark signs

·Heavy sweating that later stops (in heat stroke)
·Confusion, slurred speech, or acting strange
·Shivering (in mild hypothermia) or no shivering (in severe hypothermia)
·Fast heart rate (tachycardia) or slow heart rate (bradycardia)
·Nausea, vomiting, or loss of appetite
·Muscle cramps or weakness
·Pale, cold, clammy skin (in heat exhaustion) or hot, flushed skin (in heat stroke)
·Dizziness, fainting, or feeling lightheaded

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Red flags · escalate now

·Core temperature above 104°F (40°C) or below 95°F (35°C)
·Confusion, slurred speech, or loss of consciousness
·Hot, dry skin with no sweating in a hot environment (heat stroke)
·Seizures or uncontrollable shivering
·Very slow heart rate (under 50 beats/min) or irregular heartbeat in a cold person

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Workup

·Core temperature (rectal, esophageal, or bladder thermometer)
·Serum electrolytes (sodium, potassium, chloride, bicarbonate)
·Creatine kinase (CK) and myoglobin
·Arterial blood gas (ABG)
·Complete blood count (CBC) with platelets
·Electrocardiogram (ECG)
·Blood glucose
·Creatinine and blood urea nitrogen (BUN)

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Treatment

·Immediate rapid cooling for heat stroke: ice-water immersion, cold IV saline, or evaporative cooling (mist + fans), targeting core temperature 38.5°C (101°F) within 30 minutes
·Slow, controlled rewarming for hypothermia: passive warming (blankets, warm room) for mild (32–35°C), active external warming (warm blankets, forced-air warmers) for moderate (28–32°C), or active core rewarming (warm IV fluids, warm humidified oxygen, or extracorporeal warming) for severe (below 28°C), targeting 0.5–1°C per hour
·IV normal saline bolus (1–2 liters in adults, 20 mL/kg in children) to restore blood volume
·Remove from heat source or cold environment immediately; stop exercise
·Treat seizures with benzodiazepines (lorazepam 2–4 mg IV or diazepam 5–10 mg IV); intubate and ventilate if airway is unsafe or brain swelling worsens
·Continuous cardiac monitoring; treat dangerous arrhythmias (ventricular fibrillation, ventricular a fast heart rate (tachycardia)) with defibrillation or medications (amiodarone, lidocaine) as needed
·Correct electrolyte imbalances (give calcium for high potassium, insulin + glucose to shift potassium into cells, give bicarbonate for severe too much acid in the blood (acidosis)); transfuse blood products if clotting fails (DIC)

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NCLEX trap

·Fever medicine does not work for heat stroke because the body's temperature control center (the hypothalamus, the brain's thermostat) is broken — it is not just 'set too high' like in a normal fever. The only way to fix heat stroke is to cool the body from the outside: ice-water baths, cold packs on the groin and armpits, and cold IV fluids. Pills cannot touch this kind of heat.
·Rough handling of someone with severe hypothermia (core temperature below 28°C or 82°F) can jolt the cold, irritable heart into a deadly rhythm called ventricular fibrillation — the heart quivers instead of pumping. Also, rubbing cold skin pushes icy blood from the arms and legs back toward the core, which can drop the core temperature even more (called 'afterdrop'). Move the person gently, warm them slowly from the inside out (warm IV fluids, warm oxygen, or ECMO if available), and do not shake, rub, or jostle.
·Severe hypothermia slows the body so much it can look dead — no detectable pulse, no breathing, stiff muscles, blue skin — but the brain can still be alive and protected by the cold. The rule is 'nobody is dead until they are warm and dead.' Keep doing CPR (gently, to avoid triggering a bad heart rhythm), get the person to a hospital with rewarming equipment (ECMO is best), and do not give up until the core temperature is at least 32°C (90°F).
·In heat stroke, you must keep cooling until the core temperature reaches 38–38.5°C (100–101°F), then stop to avoid overshooting into hypothermia. After cooling, the work is not done — you must watch for organ damage (kidney failure, muscle breakdown, bleeding problems, seizures) and treat each one. Cooling is the race you must win in the first hour; after that, you are treating the wreckage the heat left behind.
·Heat stroke and severe hypothermia damage the kidneys, heart, and blood-clotting system. IV fluids help, but you must give them carefully — not too fast (the damaged heart may fail and fill the lungs with water) and not too slow (the kidneys need flow to flush out the muscle breakdown). Monitor urine output, heart rhythm, and lung sounds closely. Fluids are part of the rescue, not a quick fix.
·Heat exhaustion means the body is still trying to cool itself — the person sweats, feels weak and dizzy, may have a headache, but the brain is alert and the core temperature is below 40°C (104°F). Rest in the shade, sip cool water, and the person recovers. Heat stroke means the thermostat is broken — no sweat, core temperature above 40°C, confusion or unconsciousness, and organs are shutting down. Heat stroke is a true emergency that needs ice baths and hospital care right away. Know the line between them.

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