First Aid · Head, Dental & Environmental
Head injuries, knocked-out teeth, dehydration, heat exhaustion, heatstroke, hypothermia, frostbite, and carbon monoxide — the emergencies shaped by where you are and what the weather is doing.
Head injuries & concussion
Head injuries are stressful in the moment — especially with children. The sound of a head hitting a hard surface, or the sight of immediate swelling, tends to produce alarm disproportionate to the actual severity of most impacts. The majority of head bumps result in a bruise or a "goose egg" and nothing more serious.
The job of the first aider is to distinguish a minor impact from a concussion, and a concussion from a serious traumatic brain injury. The distinction lies not in the size of the bump but in the neurological symptoms that follow.
For a minor head bump — no red-flag symptoms:
Have the person sit down and rest in a quiet place
Apply a cold pack wrapped in a cloth to the site for up to 20 minutes to reduce swelling
Observe the person closely for the next 24 hours — checking for any developing symptoms
It is generally safe to let someone sleep after a minor head bump — the old advice to "keep them awake" is outdated. Wake them periodically to confirm they are rousable and oriented if you are concerned
Call 911 or seek emergency care immediately for:
Loss of consciousness — even briefly
Repeated vomiting — more than once after the impact
Headache that is progressively worsening
Confusion, difficulty speaking, or unusual behavior
Pupils unequal in size — one larger than the other
Clear fluid or blood draining from nose or ears
Seizure following the head injury
High-energy mechanism — car crash, fall from height
Concussion: the 24-hour watch
A concussion is a traumatic brain injury caused by an impact that disrupts normal brain function — even without loss of consciousness. Symptoms may include headache, nausea, dizziness, blurred vision, sensitivity to light or sound, difficulty concentrating, and feeling "foggy."
Concussion symptoms can appear immediately or develop over hours. The observation window for a concerning head injury is the full 24 hours following the impact. Do not leave the person alone for extended periods during this window.
A person with a suspected concussion should not return to sports, physical activity, or demanding cognitive work until cleared by a medical professional. "Return to play" decisions are medical decisions.
The pupil check
After a significant head impact, check the person's pupils. Both pupils should be round, roughly equal in size, and should both react to light — constricting when you shine a light in them.
Unequal pupils (one significantly larger than the other) after a head injury indicate increased pressure inside the skull from bleeding or swelling — a neurological emergency. Do not attribute unequal pupils to normal variation in the context of a recent head injury.
To check: use a flashlight in a dimly lit environment. Shine it briefly at one eye, then the other. Both should constrict. Both should be roughly the same size before and after.
Head injuries in children
Children's heads are proportionally large relative to their bodies and they fall frequently. Most childhood head bumps are minor. However, children may have difficulty describing their symptoms accurately — headache, "feeling weird," or unusual quietness after a head impact warrants closer observation than with adults.
For infants, any significant impact to the head warrants medical evaluation even in the absence of obvious symptoms — they cannot communicate what they're experiencing.
Knocked-out tooth
A knocked-out permanent tooth is a genuine dental emergency — but a manageable one if you act correctly within the first 30 minutes. The goal is to preserve the living cells on the root surface that allow the tooth to be reimplanted successfully.
The single most important rule: pick up the tooth by the crown, never the root. The root is covered in delicate periodontal ligament cells. Touch the root and you damage the cells that make reimplantation possible.
Pick up by the crown — the white chewing surface
Never touch the root — the lower portion that was inside the gum. Handle it as little as possible.
If dirty, rinse gently — with milk or saline only
If the tooth is visibly dirty, rinse it very briefly and gently with milk or saline. Avoid tap water if possible — it is slightly hypotonic and can damage root cells. Do not scrub, wipe, or dry the root surface. A brief rinse only.
Try to reinsert in the socket first
If the person can cooperate, have them gently place the tooth back into its socket and bite down lightly on a piece of clean gauze or cloth to hold it in position. This is the best storage medium available — the mouth provides the ideal environment for the tooth root cells.
If reinsertion isn't possible: milk, then saliva
Place the tooth in a small container of cold milk — the most effective non-socket storage medium available in most settings. If milk is unavailable, the person's own saliva in a small cup works. Do not store in tap water — the osmotic difference damages root cells.
Go immediately — dentist or emergency room
The success rate for reimplantation drops significantly after 30–60 minutes outside the socket. Time is the critical variable. Do not wait to see if it "can wait until morning." It cannot.
Baby teeth vs. adult teeth
The above protocol is for permanent (adult) teeth only. Knocked-out baby (primary) teeth are generally not reimplanted — attempting to do so can damage the developing permanent tooth underneath.
If a child loses a baby tooth, keep the child calm, control any bleeding in the socket with gentle gauze pressure, and see a dentist during normal hours to confirm no fragments remain and that root development below is not affected.
The Save-A-Tooth kit
A Save-A-Tooth emergency kit ($15–$25 at pharmacies) contains a pH-balanced preservation solution specifically formulated for tooth storage. It preserves root cells for up to 24 hours — far longer than milk. If you have children, play contact sports, or coach a team, keeping one on hand is worthwhile.
Controlling socket bleeding
After a tooth is knocked out, the socket will bleed. Have the person bite down firmly on a folded piece of gauze or clean cloth. Replace every 15–20 minutes. This is not an emergency on its own — the bleeding will usually slow and stop with sustained pressure. Focus on getting to a dentist or ER promptly.
Dehydration
Dehydration happens when the body loses more fluid than it takes in. It can occur in hot weather, cold weather, during illness, with heavy exertion, or simply from inadequate drinking throughout a long day. By the time thirst is significant, a meaningful degree of dehydration has already occurred.
For most situations, the fix is simple: rest, shade, and regular fluid intake. The important nuance is that plain water is not always enough — significant sweating depletes electrolytes, particularly sodium, and replacing large volumes of plain water without electrolytes can create a dangerous imbalance of its own.
Warning signs — mild to severe
Thirst and dry mouth or lips
Headache and general fatigue
Dizziness, especially when standing up
Dark yellow or amber urine, or infrequent urination
Muscle cramps — often the calves, feet, or hands
Severe: confusion, fainting, inability to keep fluids down
Rest in shade or a cool environment
Stop physical activity. Get out of direct sun or heat. Reduce the ongoing fluid demand before trying to replenish.
Sip water or an oral rehydration drink — don't gulp
If the person is fully conscious and able to swallow, have them sip fluids slowly. Gulping large volumes when dehydrated often triggers nausea and vomiting, making things worse.
Replace electrolytes with significant sweating
For heavy sweating during exertion or heat exposure, plain water is not enough. Use an oral rehydration salt packet (DripDrop, Pedialyte, or similar) or a sports drink to replace the sodium and potassium lost. Eating a light salty snack alongside water also helps.
Call 911 or seek medical care for severe symptoms
Confusion, fainting, inability to keep any fluids down, suspected heat illness on top of dehydration, or no urination in 6+ hours require medical attention. Severe dehydration may need IV fluids.
Urine color guide
Pale yellow: Well hydrated. This is the target.
Yellow: Slightly dehydrated. Drink more fluids.
Dark yellow / amber: Dehydrated. Rest, fluids, shade immediately.
Brown or very dark: Severely dehydrated or possible muscle breakdown from heat. Seek medical care.
Note: Some medications (B vitamins, rifampicin) and foods (beets) can alter urine color. Context matters.
Overhydration warning
Drinking excessive amounts of plain water over a short period during intense exercise in heat can dilute sodium to dangerous levels — a condition called hyponatremia. Symptoms include nausea, headache, confusion, and in severe cases, seizure. For multi-hour exertion in heat, alternate water with electrolyte drinks rather than drinking plain water exclusively.
Heat exhaustion & heatstroke
Heat exhaustion and heatstroke exist on a continuum — but they require different responses, and the line between them is the difference between "cool them down and rest" and "call 911 immediately."
Heat exhaustion
Heat exhaustion occurs when heat, exertion, and fluid loss overwhelm the body's cooling capacity. The person is still sweating — which is important — and their core temperature has not risen to the critical threshold.
Signs:
First aid:
If symptoms don't improve within 15–20 minutes, or if confusion, collapse, or hot skin develop — call 911. Heat exhaustion can progress to heatstroke.
Heatstroke
Heatstroke occurs when the body can no longer cool itself and core temperature rises to dangerous levels. It is a medical emergency. The person may have stopped sweating entirely — a critical warning sign that the cooling system has failed.
Signs:
While waiting for 911:
Hypothermia
Hypothermia occurs when the body loses heat faster than it can produce it. It does not require sub-zero temperatures. A wet hiker at 50°F in a strong wind, a swimmer pulled from a cool lake in early autumn, or an elderly person in a cool house during a power outage can all develop hypothermia. The contributing factors are exposure, moisture, wind, exhaustion, and inadequate insulation — and they compound each other.
Shivering is the body's first defense — an active, energy-consuming attempt to generate heat. When shivering stops and the person becomes confused or clumsy, core temperature has dropped to a dangerous level.
Mild hypothermia
Severe hypothermia
Move to a warm, dry place — gently
Handle a hypothermic person gently and minimize unnecessary movement. A cold heart is susceptible to arrhythmia triggered by sudden jolts or vigorous movement.
Remove wet clothing
Wet clothing accelerates heat loss. Cut it away if necessary rather than pulling it roughly over the person.
Warm the core first — chest, neck, head, and groin
Wrap in dry blankets, sleeping bags, or dry clothing. Apply warmth to the core before the extremities — warming cold hands and feet first can drive cold blood toward the heart. Warm water bottles or heat packs at the neck, armpits, and groin speed rewarming if available.
Warm drinks — only if alert and able to swallow
Warm, sweet, non-alcoholic drinks can help a mildly hypothermic person who is fully conscious and able to swallow safely. Alcohol makes hypothermia worse — it dilates blood vessels and increases heat loss despite the feeling of warmth.
Call 911 for moderate to severe hypothermia
Any confusion, stumbling, shivering that has stopped, or loss of consciousness requires emergency medical care. Rewarming severe hypothermia safely often requires controlled hospital warming.
What not to do
Do not rub or massage the extremities
Friction drives cold blood from the extremities toward the heart and can trigger dangerous cardiac arrhythmia.
Do not apply direct high heat
Hot water bottles placed directly on skin, heating pads, or placing someone directly in front of a fire can cause burns on skin that has lost normal sensation from cold. Use moderate warmth with insulation.
Do not give alcohol
Alcohol causes vasodilation, which accelerates heat loss and lowers core temperature further despite temporarily feeling warmer.
Do not make vigorous movements
Strenuous activity by the hypothermic person drives cold blood to the core and can cause cardiac complications.
Prevention outdoors
Frostbite
Frostbite occurs when skin and underlying tissue freeze. Ice crystals form inside cells, causing cellular damage. It most commonly affects the fingers, toes, ears, nose, and cheeks — the body's peripheral extremities that receive less blood flow as core temperature drops and the body prioritizes central organs.
The most critical frostbite principle: do not rewarm frostbitten tissue if there is any chance it will be exposed to cold again. Tissue that freezes, thaws, and refreezes sustains significantly more damage than tissue that remains frozen until definitive care. If the person still has miles to walk in cold conditions, leave the frozen tissue as is.
Recognizing frostbite
Frostnip (superficial)
Frostbite (deep)
Get out of the cold environment as quickly as possible
Remove wet gloves, socks, or constrictive clothing from the affected area
Protect the area from further cold and from contact with hard surfaces
Only if safe to rewarm: Soak in warm water — not hot. 99–104°F (37–40°C). Slightly above body temperature. Test with an uninjured hand first.
Separate frostbitten fingers or toes with clean dry gauze or soft cloth
Seek medical care — especially for hard, deep, blistered, or white/gray frostbite of the hands, feet, face, or ears
What not to do with frostbite
Do not rub or massage the skin
Ice crystals in frostbitten tissue lacerate cells when moved by friction. This causes additional damage.
Do not apply dry heat
Frostbitten skin has lost normal sensation. Campfire, heating pad, or hot water burns tissue that cannot perceive it is being burned.
Do not break blisters
As with burn blisters, frostbite blisters protect the tissue below. Leave them intact and seek medical care.
Do not rewarm and then walk on frostbitten feet
Thawed frostbitten tissue cannot bear weight without significant damage. If the person must walk to reach help, frozen feet bear weight better than thawed ones.
Hypothermia often accompanies frostbite
A person with significant frostbite has been in the cold long enough to lose peripheral circulation — which often means core temperature has also dropped. Check for hypothermia symptoms alongside frostbite and treat both. Core rewarming takes priority over frostbite rewarming.
Carbon monoxide poisoning
Carbon monoxide (CO) is a colorless, odorless gas produced by burning fuel — gasoline, propane, natural gas, kerosene, charcoal, wood. You cannot smell it, see it, or taste it. It is the leading cause of accidental poisoning death in the United States, and it kills a predictable number of people after every major power outage as households run generators indoors, bring propane heaters inside, or use charcoal grills in enclosed spaces.
CO poisoning mimics the flu — which is part of what makes it dangerous. A family that feels increasingly unwell in a sealed home during a winter storm may assume illness and stay inside, when the correct response is immediate evacuation.
CO poisoning vs. flu — the key differences
CO poisoning
Flu
If multiple people — or people and pets — in the same enclosed space feel unwell simultaneously with no fever, treat it as a carbon monoxide emergency until proven otherwise. Get everyone out first.
Get everyone out of the building immediately
Do not stop to gather belongings, turn off appliances, or investigate. Every second of additional exposure matters. Get everyone — including pets — outside and away from the structure.
Call 911 from outside
Call emergency services once you are outside. Do not re-enter the building for any reason until cleared by the fire department or emergency responders.
Stay in fresh air
Move away from the building and stay in fresh air. Symptoms of mild CO poisoning typically improve with fresh air exposure, but medical evaluation is still required — CO displaces oxygen in the blood and the effects can persist.
Begin CPR if someone is unresponsive
If a person is unconscious and not breathing normally after CO exposure, begin CPR. Severe CO poisoning can cause cardiac arrest.
Seek medical evaluation for everyone exposed
Even people who "feel fine" after CO exposure should be evaluated — especially children, pregnant women, and anyone with heart or lung disease. CO binds to hemoglobin and the effects may not be immediately apparent.
Prevention — non-negotiable rules
Never run a generator indoors — not in the garage, not in the basement, not in an attached shed. Outdoors only, at least 20 feet from windows, doors, and vents. The garage door being open is not sufficient.
Never use a charcoal or gas grill indoors — not in the kitchen, not on the porch with the door open, not in an enclosed space of any kind. Charcoal grills continue producing CO long after they appear to be done burning.
Never use a gas oven as a heat source — ovens are not designed for space heating and produce CO with prolonged use.
CO detectors: not optional
A working carbon monoxide detector is the single most effective prevention tool available. It provides warning before symptoms begin — especially during sleep, when CO poisoning can be fatal before the person wakes.
During a power outage
The risk of CO poisoning spikes during power outages because people use alternative heating and cooking sources indoors. Plan before the outage: identify safe outdoor locations for generator placement, keep an indoor-safe propane or electric space heater on hand (not gas), and check that CO detectors have working battery backup. Cold-weather preparedness and CO preparedness are the same topic.
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