The First Signs of Heat Exhaustion

How do you handle heat, cold, and altitude illness?

One pattern runs all three: environmental illness announces itself early, quietly, and reversibly, then escalates to emergencies that are hard to fix in the field, so the entire skill is recognizing the early stage and acting on it immediately, at the cost of a break, a layer, or a descent. Heat's early warning is exhaustion before stroke, cold's is the umbles before the shutdown, altitude's is the headache before the edemas.

The pattern's corollary is the buddy system, formalized: the person developing any of these is the last to notice (all three degrade judgment on their way in), so groups watch each other by habit, kids get watched doubly (they compensate silently and crash fast, a Chapter 51 theme), and the observation is behavioral, not interrogative: "how are you feeling" collects lies; watching the stumble, the quiet, and the untouched water bottle collects data.

Everything here builds on installed equipment: Chapter 4's forecast reading, 17's hydration, 23's layers, 27's sun-and-siesta, 36's warm nights, and 47's kit and training. This chapter is what happens when the environment gets past them.

Heat illness: the spectrum

Heat illness is a spectrum with a bright line in the middle. Heat cramps (painful muscle cramps during hot effort) are the opening bid: stop, shade, water with electrolytes, gentle stretching. Heat exhaustion is the body still fighting: heavy sweating, pale clammy skin, weakness, headache, nausea, dizziness, irritability, maybe a fast weak pulse. Heat stroke is the fight lost: the cooling system fails, core temperature runs away, and the signs flip: hot skin (dry or sweaty), confusion, slurred speech, stumbling, combativeness, collapse, seizures. Exhaustion is a stop-everything problem you fix in the shade; stroke is a life-threatening emergency you cool while help comes.

	Heat exhaustion	Heat stroke
Skin	Pale, clammy, sweating	Hot; dry or still sweating
Mind	Tired, irritable, dizzy	Confused, slurring, combative, out
Action	Shade, cool, drink, rest	Cool aggressively + SOS now

The mental status line is the diagnostic that matters: a hot person who's miserable but tracking is exhausted; a hot person who's confused, ataxic, or "just not right" is having a heat stroke until proven otherwise, and the response is Chapter 48's fast protocol energy, applied with water.

Treating heat: shade, water, and the aggressive version

Heat exhaustion: stop the activity completely (this is non-negotiable and the part pride fights), shade (real shade, the Chapter 8 tarp, the creek's trees), cool actively (wet the clothing, fan, cold water on head, neck, wrists), drink (water plus electrolytes: the kit's ORS, the sports powder, or salted snacks with water; plain water alone in quantity can worsen the salt picture), and rest until genuinely recovered, which means the rest of the hot hours, not fifteen minutes. Someone who reached exhaustion today is more vulnerable tomorrow; the trip plan adjusts.

Heat stroke: SOS/call first (Chapter 42), then cool by every means at once: into the creek or lake if safely possible (supported, airway watched: immersion is the gold standard the wilderness sometimes actually offers), or continuous dousing with water and fanning, ice from the cooler to neck, armpits, and groin, clothing off. Don't wait for shivering or "enough": cooling continues until mental status returns or help takes over. Nothing by mouth for the confused (choking risk). This one kills fit young people at summer trailheads every year, and aggressive early cooling is the entire difference.

The humidity footnote that changes thresholds: sweat only cools by evaporating, so humid heat (the Southeast's specialty) disables the body's system at temperatures dry heat shrugs at. Chapter 43's heat index is the honest number, and the siesta schedule (Chapter 27) plus the hydration cadence (Chapter 39) are the preventions already installed.

Hypothermia: the umbles

Hypothermia's early stage announces in the umbles: mumbles (quiet, withdrawn, slurring), stumbles (clumsy on easy ground), fumbles (zippers and buckles suddenly hard), grumbles (personality goes flat or foul), plus shivering, in a person who's been cold, wet, windy, or all three, at temperatures nowhere near freezing (Chapter 23's 50°F-and-drizzle is the classic venue). The victim will deny everything, which is part of the illness: the cooling brain defends its own decline.

Mild (shivering, umbling, still coherent): fix it now and it's an anecdote. Out of wind and wet (shelter, the vehicle, the tent), wet clothes off and dry layers on (the sealed sleep set earns its keep), insulate from the ground (Chapter 10's physics in triage form), feed the furnace (sugar first, then sustained calories: this is Chapter 36's warm-body doctrine at clinical strength), warm sweet drinks if swallowing is normal, hot water bottles (Chapter 36's trick) at chest, armpits, and groin, and gentle activity once fuel is aboard. Recovery is real when shivering fades and the person returns to themselves.

Severe (shivering stops, profound confusion or unconsciousness, rigid): this is an SOS emergency handled with extreme gentleness: no rubbing, no rough handling (a cold heart is electrically irritable, and rough movement can stop it), no walking them around. Build the hypothermia burrito: dry insulation everywhere including underneath, vapor barrier outside (tarp, emergency blanket), hot bottles wrapped at the core only, horizontal, handled like glass, evacuated professionally. Severely hypothermic people have survived astonishing things when handled gently; "cold and dead" is a hospital determination, not a field one, and rescuers train on exactly that phrase.

Frostbite: the freezing injury

The ladder: frostnip (cold, pale, numb skin: fingertips, toes, nose, ears; painful on rewarming, no lasting damage) is the warning shot: warm it now (fingers in armpits, the buddy's belly per winter tradition, warm hands cupping the nose) and upgrade the protection (dry gloves, the gaiter, Chapter 43's wind chill respected). Superficial frostbite (skin waxy, white, hard on the surface, soft beneath) and deep frostbite (hard through, wooden, blistering later) are tissue actually freezing, and the field rules invert intuition:

Never rub (frozen tissue is full of ice crystals; rubbing is a blender), never rub with snow (folklore with a body count), no fire-and-stove rewarming (numb tissue burns without reporting it: the frostbitten hand roasted over the fire is a double injury classic), and don't thaw what might refreeze: freeze-thaw-freeze destroys tissue far worse than staying frozen while you evacuate, so a frozen foot that has to walk out, walks out frozen: hospital rewarming is controlled, warm-water-bath, and analgesized, which the field can't offer.

What the field does do: get shelter, treat the whole person for hypothermia (they're linked; the cold that froze the toes is working on the core), splint-and-pad frozen parts, skin-to-skin warmth for frostnip and small superficial patches when refreezing is off the table, and evacuate. Prevention was cheaper the whole time: dry gloves and socks (Chapter 26's rotation), the wind covered (Chapter 43), boots not laced strangling-tight (circulation is heat delivery), and the buddy face-check in real cold, because noses frostnip without their owners' knowledge.

Altitude: the headache that means something

Acute mountain sickness (AMS) arrives above roughly 8,000 feet in the unacclimatized: headache plus fatigue, nausea, poor appetite, dizziness, and bad sleep, typically 6–24 hours after arrival: essentially a hangover you didn't earn. It's common (a large minority of lowlanders feel it at Rocky Mountain trailhead elevations), usually self-limiting, and the response ladder is: stop ascending (sleep no higher tonight), hydrate, rest, treat the headache, and ascend again only after symptoms resolve. Worsening symptoms at the same altitude mean one thing: descend, and even 1,000–2,000 feet works wonders.

The two emergencies live past AMS and both answer to the same word. HACE (brain edema): the AMS patient becomes ataxic (can't walk heel-to-toe: the field test), confused, irrational. HAPE (lung edema): breathlessness at rest, a wet cough, gurgling, blue lips, drowning from inside. Both are descend now, SOS now emergencies where descent is the medicine and nothing else substitutes.

Prevention is scheduling, and campers can actually do it: arrive at altitude and sleep a night at an intermediate elevation before going high (the drive-from-sea-level-to-a-10,000-foot-trailhead itinerary is the classic AMS factory), above 8,000 feet raise sleeping elevation gradually (the climb-high-sleep-low tradition encodes it), keep the first altitude day gentle, hydrate, and skip alcohol the first nights. The acetazolamide conversation belongs to a doctor before a fast-ascent trip; the descend-when-worse rule belongs to everyone.

The shared doctrine: watch, act, log

The three environments compress into one camp practice. Watch: the buddy scan at breaks (who's quiet, who's stumbling, who hasn't drunk), the kid and dog check on schedule, the self-honesty that treats your own headache, clumsiness, or chill as data. Act at stage one: the break, the layer, the shade, the descent, taken immediately and socially normalized ("we stop for hot spots and umbles, nobody apologizes": the Chapter 26 rule, generalized). Log: times and changes on the incident sheet when anything real starts, because "is she better or worse than an hour ago" is the question every protocol turns on.

And the shared prevention, one sentence per environment: heat wants the siesta schedule, water with salt, and honest humidity math; cold wants dry layers, fuel, and wind respect at temperatures that sound safe; altitude wants slow sleeping-elevation gains and a gentle first day. All three want margins, which has been this book's whole religion since Chapter 2.

Trailhead Takeaways

• One pattern, three environments: catch stage one (exhaustion, umbles, AMS headache) and fix it cheap. Stage two is an evacuation.
• Heat's bright line is mental status: hot and miserable = shade, cool, electrolytes, done for the day. Hot and confused = cool aggressively by every means and SOS.
• Hypothermia announces in umbles at 50°F and drizzle, blizzard or none. Mild: dry, insulate, sugar, hot bottles. Severe: burrito, glass-gentle, SOS, no rubbing.
• Frostbite: never rub, never fire-thaw, never thaw what might refreeze. Frostnip is the warning to act on.
• Altitude: headache-plus above 8,000 feet means sleep no higher; worsening means descend; ataxia or breathless-at-rest means descend now with SOS.
• Watch buddies, not their answers. The illness lies through its owner in all three environments.
• Prevention was installed chapters ago: siesta and salt, dry layers and fuel, slow sleeping-altitude gains.

Where Trips Go Sideways

• "She's just tired." Quiet, stumbling, zipper-fumbling on a wet 52°F afternoon, and the group's diagnosis was fatigue. The umbles were textbook and nobody had read the textbook. Sugar, dry layers, and an hour would have ended it; instead the afternoon got serious.
• Pushing through the hot headache. Nausea and dizziness at the switchbacks, answered with "we're almost there." The summit got them; the confusion started twenty minutes later, a mile from water. Exhaustion is the last cheap exit on that road.
• The fireside thaw. Wooden-numb toes presented to the flames, which cooked what they couldn't feel. Frostbite plus burn, the classic double. Warm water and gentleness at the hospital was always the plan; the fire never was.
• Trailhead at 10,200 by lunch, summit bid by dawn. Sea level Thursday, misery Friday, and the vacation spent acclimatizing to a schedule nobody built acclimatization into. One intermediate night was the whole fix, known and skipped.
• Rubbing the cold man warm. Vigorous friction, a jog to "get the blood moving," and handling that severe hypothermia punishes. Gentle is the protocol precisely because it's counterintuitive; the burrito and the SOS were the loving response.

Frequently asked

What are the first signs of heat exhaustion?

Heavy sweating with pale, clammy skin, headache, weakness, dizziness, nausea, and irritability during hot effort: the body still fighting, loudly. Treat it as stop-everything: shade, active cooling, water with electrolytes, and rest for the remaining hot hours. Confusion or hot skin moves the diagnosis to heat stroke and the response to aggressive cooling plus SOS.

What is the difference between heat exhaustion and heat stroke?

Mental status. Exhaustion is miserable but tracking: tired, dizzy, sweaty, coherent. Stroke is the cooling system failed: hot skin, confusion, slurred speech, stumbling, collapse. Exhaustion recovers in the shade; stroke is a life-threatening emergency cooled by immersion or continuous dousing while help comes.

How do you treat hypothermia while camping?

Mild (shivering plus the umbles): shelter from wind and wet, dry clothes, ground insulation, sugar then real calories, warm sweet drinks, hot water bottles at the core. Severe (shivering stopped, profound confusion): SOS, the insulated burrito wrap, hot bottles at the chest, and glass-gentle handling: no rubbing, no walking them.

How do you prevent altitude sickness?

Schedule it away: sleep a night at intermediate elevation before going high, keep sleeping-altitude gains modest above 8,000 feet, make the first day gentle, hydrate, and skip alcohol early. If the headache-plus arrives anyway: no higher sleeping until it resolves, and descent the moment anything worsens, because losing even 1,000–2,000 feet treats what nothing else in the field can.