Hypothermia means your core body temperature falls below 35 °C (95 °F). It happens when your body loses more heat than it produces. This can occur outdoors in cold, wet, or windy weather, but also indoors in frail or ill people, or after certain drugs or illnesses. Hypothermia affects every organ system and can be life-threatening, especially as the temperature drops further. NCBI+1
Hypothermia means your core body temperature drops below 35 °C (95 °F). Cold air, wet clothes, wind, long exposure outdoors, or medical problems can all pull heat out of the body. As the temperature falls, the brain, heart, lungs, kidneys, and muscles slow down. Mild hypothermia brings shivering and confusion. Moderate and severe hypothermia can stop shivering, slow the heart, cause dangerous heart rhythms, and lead to coma and cardiac arrest. Doctors stage hypothermia by core temperature (mild 32–35 °C, moderate 28–32 °C, severe <28 °C) and clinical signs, then rewarm you safely with external heat, warm oxygen and IV fluids, and sometimes invasive rewarming like ECMO (heart-lung machine). Early recognition, gentle handling, and controlled rewarming save lives. NCBI+2PMC+2
Hypothermia is a state where the core (deep) body temperature is too low for normal body functions. As the core cools, the brain, heart, lungs, kidneys, and blood chemistry slow down. Mild hypothermia causes shivering and confusion. Moderate hypothermia brings slurred speech, poor coordination, and drowsiness. Severe hypothermia can lead to unconsciousness, dangerous heart rhythms, and cardiac arrest. Immediate protection from further heat loss and careful rewarming save lives. NCBI+1
Other names
People also use these names: accidental hypothermia, environmental hypothermia, cold stress injury, peri-exposure hypothermia (outdoors), and secondary hypothermia (due to a medical problem or drug). Many clinical texts also group severity using the Swiss staging system (HT I–IV), which is based on clinical signs and core temperature. umem.org+1
Types
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Mild hypothermia (about 32–35 °C)
The person is usually awake and shivering. Skin is cold and pale. Fine motor control is poor. Shivering is the body’s natural heat-making tool. People can often be rewarmed with shelter, dry clothing, and warm fluids. Life in the Fast Lane • LITFL -
Moderate hypothermia (about 28–32 °C)
Shivering slows or stops, which is a bad sign. Speech is slurred. Thinking is slow. Movement is clumsy. The heart becomes very slow (bradycardia), and the person may drift into stupor. Active rewarming is needed. PMC -
Severe hypothermia (<28 °C)
The patient is often unconscious. Breathing is shallow and slow. Dangerous heart rhythms appear, such as atrial fibrillation or ventricular arrhythmias. Cardiac arrest can occur. Handling must be very gentle to avoid provoking an arrhythmia. Specialized active core rewarming is required. PMC+1
(Many clinicians also use the Swiss clinical stages HT I–IV to guide actions in the field and hospital.) umem.org
Causes
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Cold outdoor exposure
Long time in cold air, wind, or rain pulls heat from the body faster than it can be made, especially without proper clothing. Wind and wetness speed heat loss. CDC -
Cold water immersion
Water conducts heat away about 25x faster than air. Even “cool” water can drop core temperature rapidly, especially with waves and movement. PMC -
Wet clothing
Wet fabric on the skin drains heat by conduction and evaporation. Removing wet clothes is a first step in care. NCBI -
Inadequate shelter or heating indoors
Older adults, infants, and people with limited mobility can cool in unheated rooms because they generate less heat and sense cold less. NCBI -
Alcohol use
Alcohol widens blood vessels in the skin, making you feel warm while you lose core heat faster and impairing judgment to seek shelter. NCBI -
Sedatives or opioids
Drugs that slow the brain and breathing reduce heat production and the drive to move to a warmer place. NCBI -
Antipsychotics and other medications
Some medicines interfere with temperature control in the brain and reduce shivering. NCBI -
Sepsis (severe infection)
Serious infections can cause low body temperature, especially in frail or elderly people, by altering metabolism and blood flow. NCBI -
Hypothyroidism / Myxedema
Low thyroid hormone slows metabolism, so the body makes less heat and responds poorly to cold. NCBI -
Adrenal insufficiency
Lack of cortisol and catecholamines impairs heat production and blood vessel responses. NCBI -
Hypoglycemia (low blood sugar)
Glucose fuels heat production; low levels reduce shivering and brain function, worsening cooling. NCBI -
Malnutrition
Low body fat and low muscle mass reduce insulation and heat generation. NCBI -
Stroke or brain injury
Damage to the hypothalamus or impaired consciousness reduces thermoregulation and shivering. NCBI -
Spinal cord injury
Loss of autonomic control below the injury limits blood vessel and sweating responses, making temperature unstable. NCBI -
Advanced age (frailty)
Older adults have less shivering, less subcutaneous fat, and may not sense cold, so they cool easily. NCBI -
Infancy
Infants lose heat quickly due to larger surface area and limited shivering; they rely on “brown fat” which can be overwhelmed. NCBI -
Major trauma / blood loss
Shock and exposure during rescue reduce heat, and cold worsens blood clotting, creating a dangerous cycle. PMC -
Anorexia or eating disorders
Low reserves and hormonal changes reduce heat production. NCBI -
Prolonged immobility
People lying on cold surfaces (falls, intoxication) lose heat into the ground and cannot generate heat by movement. NCBI -
Peri-operative cooling
During anesthesia, the body cannot regulate temperature; operating rooms are cool and skin is exposed, so patients cool unless warmed. NCBI
Symptoms
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Shivering
An early warning sign. Muscles contract to make heat. If shivering stops while still cold, this is serious and often signals moderate to severe hypothermia. OSHA -
Cold, pale, or waxy skin
Blood leaves the skin to conserve heat for vital organs, making the skin feel cold. NCBI -
Numbness and tingling
Nerves conduct more slowly when cold; hands and feet lose feeling first. NCBI -
Clumsiness and poor coordination
Cold muscles and slower nerve signals cause stumbling, dropping objects, and difficulty with fine tasks. Mayo Clinic -
Slurred or mumbling speech
The tongue and facial muscles stiffen, and the brain slows. Mayo Clinic -
Confusion and poor judgment
Cold affects brain function; people may remove clothing or make unsafe choices. OSHA -
Drowsiness or fatigue
The brain conserves energy; people want to lie down and sleep, which increases risk. Mayo Clinic -
Slow, shallow breathing
The respiratory center slows, and chest muscles stiffen. Mayo Clinic -
Slow pulse (bradycardia)
The heart naturally slows as it cools; very slow rates signal advanced hypothermia. NCBI -
Blue lips or fingertips (cyanosis)
Low blood flow and low oxygen in cold tissues cause bluish color. NCBI -
Frequent urination (cold diuresis)
Cold shifts blood to the central body; the kidneys excrete extra fluid, leading to dehydration. NCBI -
Rigid or stiff muscles
Cold muscles and joints become rigid; severe cases look like rigor. NCBI -
Hallucinations or irrational behavior
Brain cooling can cause odd behavior, like paradoxical undressing. This is a medical emergency. NCBI -
Loss of consciousness
Severe cooling depresses the brain; the person may be unresponsive. Mayo Clinic -
Cardiac arrest
Extreme hypothermia can stop the heart. Victims may appear dead but can sometimes be resuscitated with careful rewarming. fhn.org
Diagnostic tests
A) Physical examination (bedside observations)
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Core temperature measurement with a low-reading thermometer
A rectal or esophageal probe that reads down to at least 25 °C is needed; standard thermometers may “bottom out,” hiding severe hypothermia. PMC -
Swiss clinical staging (HT I–IV)
Simple signs—shivering, level of consciousness, presence of vital signs—help estimate severity and guide rewarming and transport decisions when exact temperature is unknown. umem.org -
Airway, breathing, circulation check
Look for slow or absent breathing and pulse. Count for a full minute because rates are very slow. Gentle handling prevents arrhythmias. PMC -
Neurologic assessment (GCS/AVPU)
Hypothermia reduces responsiveness. Serial checks track improvement during rewarming. NCBI -
Skin inspection
Note pallor, mottling, frostbite, or immersion injuries. These suggest exposure time and complications. CDC
B) Manual/bedside tests (simple clinical maneuvers)
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Capillary refill and peripheral perfusion
Cold-induced vasoconstriction makes refill slow; tracking this helps assess perfusion during rewarming. NCBI -
Two-person gentle log-roll
Used to examine the back and prevent sudden movements that could trigger dangerous heart rhythms in severe hypothermia. PMC -
Passive rewarming response
Applying insulation and a warm environment while observing for return of shivering and improved mental status helps confirm mild cases and guides escalation. PMC -
Shivering status check
Presence or absence of shivering is itself a “test” that correlates with severity (present in mild; often absent in moderate–severe). Life in the Fast Lane • LITFL -
Point-of-care glucose
A rapid finger-stick detects hypoglycemia, a common and reversible contributor to hypothermia and confusion. NCBI
C) Laboratory and pathological tests
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Serum electrolytes and renal function
Cold diuresis and dehydration cause sodium shifts and possible renal injury; potassium may rise during rewarming. NCBI -
Arterial or venous blood gas (ABG/VBG)
Shows respiratory and metabolic changes (e.g., respiratory acidosis or metabolic acidosis). Temperature-corrected values may be used in some settings. PMC -
Serum glucose
Hypoglycemia is common and must be corrected promptly to restore brain function and shivering. NCBI -
Complete blood count (CBC) and coagulation studies (PT/INR, aPTT, fibrinogen)
Cold impairs clotting pathways; labs can mimic coagulopathy and should be interpreted with warmth-aware techniques. PMC -
Creatine kinase (CK) and myoglobin
Prolonged immobility and cold can cause muscle breakdown (rhabdomyolysis), detected by elevated CK/myoglobin. NCBI -
Thyroid panel (TSH, free T4) and morning cortisol
Hypothyroidism and adrenal insufficiency can cause or worsen hypothermia; testing looks for these triggers. NCBI -
Lactate
High lactate suggests poor tissue perfusion, shock, or sepsis alongside hypothermia and helps track recovery. PMC -
Toxicology screen (alcohol and sedatives)
Identifies substances that depress the brain and reduce heat production or judgment. NCBI
D) Electrodiagnostic tests
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12-lead ECG
Classic findings include sinus bradycardia, prolonged PR/QRS/QT, atrial fibrillation, and the Osborn (J) wave—a dome-shaped deflection at the J-point—seen especially as temperatures fall below ~32 °C. These changes improve with rewarming. ECG also detects life-threatening arrhythmias. AHA Journals+2New England Journal of Medicine+2
E) Imaging tests
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Point-of-care ultrasound (POCUS) and chest X-ray; targeted CT when indicated
Cardiac ultrasound helps detect motion during arrest (“not dead until warm and dead”). Chest imaging can show aspiration, pulmonary edema, or pneumonia from exposure. CT/MRI are used selectively to rule out head injury or stroke when the story is unclear. PMC
Treatment
First Aid
Take the following steps if you think someone has hypothermia:
- If the person has any symptoms of hypothermia that are present, especially confusion or problems thinking, call 911 right away.
- If the person is unconscious, check the airway, breathing, and circulation. If necessary, begin rescue breathing or CPR. If the victim is breathing fewer than 6 breaths per minute, begin rescue breathing.
- Take the person inside to room temperature and cover with warm blankets. If going indoors is not possible, get the person out of the wind and use a blanket to provide insulation from the cold ground. Cover the person’s head and neck to help retain body heat.
- Once inside, remove any wet or tight clothes and replace them with dry clothing.
- Warm the person. If necessary, use your own body heat to aid the warming. Apply warm compresses to the neck, chest wall, and groin. If the person is alert and can easily swallow, give warm, sweetened, nonalcoholic fluids to aid the warming.
- Stay with the person until medical help arrives.
Do Not
- Do NOT assume that someone found lying motionless in the cold is already dead.
- Do NOT use direct heat (such as hot water, a heating pad, or a heat lamp) to warm the person.
- Do NOT give the person alcohol.
Non-pharmacological treatments (therapies and other measures)
1) Remove from cold and wind
Description: Move the person to a sheltered place (vehicle, hut, tent, building). Block wind with barriers, close vents, and keep the person horizontal. Avoid rough handling. Cut away wet clothing only when a windproof/waterproof layer is ready. Purpose: Stop further heat loss fast. Mechanism: Reduces convective and evaporative heat loss so the body’s remaining heat and any added heat can raise core temperature again. Wilderness Medicine Training Center+1
2) Gentle, minimal handling
Description: Keep the casualty flat, avoid sudden movements, and support the head and trunk together during transfers. Purpose: Prevent a sudden drop in blood pressure and avoid provoking ventricular fibrillation (a lethal rhythm) in severe hypothermia. Mechanism: A cold heart is irritable; jolts can trigger arrhythmias. Gentle handling lowers mechanical irritation and afterload swings. Wilderness Medicine Training Center+1
3) Insulate and vapor barrier (“wrap”)
Description: Use a dry insulating layer (blankets, sleeping bag, bubble wrap), plus a wind- and water-proof outer layer. Include the head and neck. Purpose: Trap body heat and stop evaporation. Mechanism: Increases resistance to heat flow from skin to environment and stops evaporative cooling from wet skin/clothes. Wilderness Medicine Training Center
4) Remove wet clothing; add dry layers
Description: Cut off wet clothes if possible without excessive movement; replace with dry, layered clothing and hats. Purpose: Stop evaporative cooling from wet fabrics. Mechanism: Evaporation pulls large amounts of heat; dry layers restore insulation and limit heat loss. Wilderness Medicine Training Center
5) Passive external rewarming (PER)
Description: Wrap, insulate, and shelter without adding external heat sources—best for mild hypothermia with shivering. Purpose: Let the body’s own heat production re-raise core temperature. Mechanism: Shivering thermogenesis combined with insulation increases core temperature a few degrees per hour when energy stores are adequate. Wilderness Medicine Training Center
6) Active external rewarming (AER) with heat packs
Description: Apply chemical or electrical heat packs to high-flow areas (axillae, chest, back, groin), not to hands/feet first. Purpose: Add safe heat near central circulation. Mechanism: Conductive heat transfer near the trunk warms blood returning to the core, improving afterdrop risk compared with distal warming. Wilderness Medicine Training Center
7) Warm, humidified oxygen
Description: Give warmed, humidified oxygen if available; room-temperature oxygen is still helpful. Purpose: Support breathing and reduce respiratory heat loss. Mechanism: Heated, humidified gas lessens conductive and evaporative cooling across airway surfaces and improves oxygen delivery during rewarming. Wilderness Medicine Training Center+1
8) Warmed IV fluids (preferably normal saline)
Description: Start warmed (38–42 °C) isotonic crystalloids for dehydration or shock. Avoid lactated Ringer’s in severe hypothermia with poor metabolism of lactate. Purpose: Treat hypovolemia and prevent further internal cooling from cold infusions. Mechanism: Heated fluids add core heat and restore preload. Wilderness Medicine Training Center
9) Heated forced-air systems (e.g., “Bair Hugger”)
Description: Use a hospital forced-air warming blanket over the chest/back. Purpose: Deliver controlled convective heat over large surface areas in moderate hypothermia. Mechanism: Increases convective heat flux to skin; warmed blood returns to the core. PMC
10) Warmed IV/IO glucose for hypoglycemia
Description: Check glucose; treat if low with warmed dextrose solutions. Purpose: Hypoglycemia worsens hypothermia and stops shivering. Mechanism: Restoring glucose powers shivering thermogenesis and brain function; warmed infusate adds heat. NCBI
11) Cardiac monitoring and staged rewarming
Description: Place on monitor; correct electrolyte and acid-base problems slowly while core temperature rises. Purpose: Catch malignant rhythms early and guide safe pacing/defibrillation timing. Mechanism: Electrical and metabolic stability improves as core temperature increases. PMC
12) Avoid unnecessary field CPR if signs of life present and transport to ECMO center when indicated
Description: If pulses and breathing are present, focus on rewarming and rapid transfer. For cardiac arrest due to hypothermia, consider ECLS/ECMO when available. Purpose: Optimize survival with “not dead until warm and dead” principle. Mechanism: ECMO provides oxygenation and active core rewarming with best outcomes in selected patients. PMC+1
13) Core temperature monitoring (esophageal/rectal) when resources allow
Description: Use a low-reading thermometer; prefer esophageal probe in intubated patients. Purpose: Guide therapy and avoid over- or under-rewarming. Mechanism: Accurate core temperature correlates with risk, rhythm, and rewarming rate. Wilderness Medicine Training Center
14) Rewarming shock prevention (head-down tilt not recommended)
Description: Keep patient flat; avoid unnecessary upright positioning during early rewarming. Purpose: Prevent sudden drop in blood pressure (rewarming collapse). Mechanism: Peripheral vasodilation during rewarming redistributes blood; careful posture reduces afterload swings. PMC
15) Truncal priority warming (avoid aggressive extremity massage)
Description: Warm the trunk first; do not vigorously massage cold limbs. Purpose: Reduce afterdrop (continued fall in core temperature after rescue). Mechanism: Truncal heat warms returning venous blood; limb massage pushes cold, acidotic blood centrally. Wilderness Medicine Training Center
16) Stopgap heat sources (vehicle heater, stove at safe distance)
Description: In remote settings, use safe ambient heat sources while insulating the patient. Purpose: Bridge until definitive warming is available. Mechanism: Raises environmental temperature and reduces gradient-driven heat loss. Wilderness Medicine Training Center
17) Active internal rewarming: warmed IV fluids and irrigation
Description: In hospital, options include warmed IV fluids, warmed bladder or gastric lavage in selected cases. Purpose: Add heat directly to core compartments. Mechanism: Conduction/convection of heat to internal organs and blood. PMC
18) Invasive core rewarming: thoracic/peritoneal lavage
Description: Circulate warmed saline into chest or abdomen for severe hypothermia when ECMO is not available. Purpose: Rapid core heat transfer. Mechanism: Warmed fluid directly exchanges heat with central blood and organs. PMC
19) Extracorporeal life support (ECLS/ECMO) or cardiopulmonary bypass
Description: Use VA-ECMO/CPB for hypothermic cardiac arrest or profound instability. Purpose: Highest rewarming rates and best chance of survival with good neurologic outcome in selected patients. Mechanism: External circuit warms, oxygenates, and pumps blood while organs recover. PMC+1
20) Post-rewarming temperature control
Description: After ROSC or recovery, avoid fever and avoid re-cooling; maintain normal temperature as per post–cardiac arrest guidelines. Purpose: Protect brain and heart. Mechanism: Normothermia reduces secondary injury. AHA Journals+1
Drug treatments
Important: There is no “hypothermia-curing” drug. Medicines below are adjuncts for complications (shivering, pain, hypoglycemia, hypotension, arrhythmias) while rewarming does the real work. Many uses here are off-label for accidental hypothermia; dosing and safety come from FDA labels and resuscitation guidelines. Always follow local protocols.
1) Warmed Dextrose (IV)
Class: Carbohydrate solution. Dose/Time: D10–D50 IV as needed for hypoglycemia, titrated to glucose; infuse warmed. Purpose: Correct low blood sugar to restore shivering and brain function. Mechanism: Provides immediate glucose; warmed fluid adds heat. Side effects: Hyperglycemia, fluid shifts, hypokalemia if large volumes. Evidence/label: FDA dextrose injection labeling outlines administration and risks (e.g., hypokalemia). FDA Access Data+1
2) Thiamine (IV) before glucose in malnutrition/alcohol-use risk
Class: Vitamin B1. Dose/Time: 100 mg IV prior to or with glucose in at-risk patients. Purpose: Prevent Wernicke encephalopathy after glucose bolus. Mechanism: Cofactor for carbohydrate metabolism. Side effects: Rare hypersensitivity reactions. Evidence/label: Parenteral multivitamin/thiamine safety notes in FDA labeling. FDA Access Data+1
3) Warmed Normal Saline (IV)
Class: Isotonic crystalloid. Dose/Time: Boluses for hypovolemia; warmed to 38–42 °C. Purpose: Restore preload and add heat. Mechanism: Volume expansion + conductive heat. Side effects: Hemodilution, acidosis if excessive. Evidence: Hypothermia guidelines recommend warmed isotonic fluids. Wilderness Medicine Training Center
4) Epinephrine (cardiac arrest/hypotension per ACLS)
Class: Catecholamine vasopressor. Dose/Time: Per ACLS; effectiveness may be reduced at very low core temp—rewarm concurrently. Purpose: Support perfusion during arrest/shock. Mechanism: Alpha/beta-agonist increases coronary/cerebral perfusion pressure. Side effects: Tachyarrhythmias, ischemia. Evidence/label: AHA algorithms/guidelines; FDA epinephrine labeling for dosing and risks. cpr.heart.org+2cpr.heart.org+2
5) Norepinephrine (hypotension after volume)
Class: Vasopressor. Dose/Time: Titrate IV infusion to MAP goals. Purpose: Treat persistent hypotension after fluids. Mechanism: Alpha-1 (vasoconstriction) with some beta-1. Side effects: Ischemia, extravasation injury. Evidence/label: FDA norepinephrine labeling warns about ischemia in hypovolemia; use after volume. FDA Access Data
6) Amiodarone (refractory VT/VF per ACLS)
Class: Class III antiarrhythmic. Dose/Time: ACLS dosing for shock-refractory VT/VF; defibrillation attempts may be delayed until core temp rises (per guidelines). Purpose: Manage malignant ventricular rhythms. Mechanism: Blocks K⁺ channels, prolongs repolarization. Side effects: Hypotension, bradycardia. Evidence/label: FDA amiodarone labeling; resuscitation guidance notes temperature considerations. FDA Access Data+2FDA Access Data+2
7) Magnesium sulfate (torsades or low Mg)
Class: Electrolyte/antiarrhythmic. Dose/Time: Standard IV dosing for torsades de pointes; correct measured hypomagnesemia. Purpose: Stabilize myocardium. Mechanism: Modulates calcium influx and repolarization. Side effects: Hypotension, respiratory depression if rapid/high dose. Evidence/label: FDA magnesium sulfate labeling. FDA Access Data
8) Oxygen (warmed, humidified if possible)
Class: Medical gas. Dose/Time: Titrate to normal oxygen saturation; avoid hyperoxia post-ROSC. Purpose: Treat hypoxemia; reduce airway heat loss if warmed. Mechanism: Improves oxygen delivery; reduces evaporative loss. Side effects: Dry airways if cold/dry; oxygen toxicity if excessive. Evidence: WMS and AHA guidance. Wilderness Medicine Training Center+1
9) Dexmedetomidine (shivering control, sedative adjunct in monitored settings)
Class: Alpha-2 agonist sedative. Dose/Time: ICU/procedural sedation dosing with close monitoring. Purpose: Reduce shivering and anxiety during rewarming under clinician care. Mechanism: Central alpha-2 agonism decreases shivering threshold. Side effects: Bradycardia, hypotension. Evidence/label: FDA dexmedetomidine labeling (Precedex and generics). FDA Access Data+1
10) Meperidine (selected cases for shivering with monitoring)
Class: Opioid analgesic. Dose/Time: Small IV doses as ordered, monitor closely; avoid in many older adults/CKD. Purpose: Reduce shivering; treat pain. Mechanism: Lowers shivering threshold via central actions. Side effects: Respiratory depression, neurotoxicity (normeperidine), dependence. Evidence/label: FDA meperidine labeling. FDA Access Data
11) Buspirone (oral, adjunct for shivering in monitored inpatients)
Class: Anxiolytic (5-HT1A partial agonist). Dose/Time: Oral per label; sometimes combined with meperidine in monitored settings (off-label). Purpose: Lower shivering threshold. Mechanism: Central serotonergic effects modulate thermoregulation. Side effects: Dizziness, nausea. Evidence/label: FDA buspirone labeling/PSG. FDA Access Data+1
12) Benzodiazepines (e.g., midazolam) for severe agitation
Class: Sedative-hypnotic. Dose/Time: Titrated IV/IM under monitoring. Purpose: Control agitation that worsens heat loss and impedes rewarming. Mechanism: GABAergic CNS depression reduces metabolic demand and muscle activity. Side effects: Respiratory depression, hypotension. Evidence: Incorporated in hospital protocols and critical-care texts; use per ACLS sedation practices. cpr.heart.org
13) Analgesics (e.g., fentanyl) during procedures
Class: Opioid analgesic. Dose/Time: Small, titrated doses with monitoring. Purpose: Pain control to allow wrapping, lines, or lavage. Mechanism: Centrally reduces pain signals; indirect reduction of stress-driven heat loss. Side effects: Respiratory depression. Evidence: Standard critical-care practice; avoid oversedation. PMC
14) Antiemetics (e.g., ondansetron)
Class: 5-HT3 antagonist. Dose/Time: Standard IV dosing for nausea/vomiting that interferes with oxygenation or oral warming. Purpose: Prevent aspiration; improve comfort. Mechanism: Blocks vagal/central serotonin receptors. Side effects: Headache, QT prolongation. Evidence: Common emergency-care practice; follow label guidance. PMC
15) Insulin (if hyperglycemia impairs rewarming)
Class: Hormone. Dose/Time: IV insulin per sliding scale in ICU; not to “treat hypothermia,” only to control high glucose. Purpose: Improve metabolic control. Mechanism: Facilitates glucose uptake. Side effects: Hypoglycemia, hypokalemia. Evidence/label: FDA insulin labeling; use per hospital protocols. FDA Access Data
16) Electrolyte replacements (K⁺, Mg²⁺, Phos) as measured
Class: Electrolytes. Dose/Time: Replace based on labs and ECG. Purpose: Correct arrhythmia risks and support muscle function. Mechanism: Restores membrane potentials and ATP production. Side effects: Over-correction risks. Evidence: Hypothermia care reviews/guidelines. PMC
17) Antibiotics (only if infection triggered cooling)
Class: Antibacterials. Dose/Time: Per suspected source and sepsis protocols. Purpose: Treat infections that caused secondary hypothermia (e.g., sepsis). Mechanism: Pathogen kill reduces ongoing heat loss drivers. Side effects: Class-specific. Evidence: Sepsis standards; not for primary cold exposure. PMC
18) Vasopressors other than norepinephrine (e.g., vasopressin) per shock state
Class: Vasopressor. Dose/Time: Add-on to catecholamines in refractory shock with careful monitoring. Purpose: Support MAP. Mechanism: V1-mediated vasoconstriction. Side effects: Ischemia. Evidence: Post-arrest/shock guidance; clinician discretion. AHA Journals
19) Antidysrhythmics other than amiodarone (e.g., lidocaine) if indicated
Class: Class Ib antiarrhythmic. Dose/Time: Per ACLS when appropriate. Purpose: Manage ventricular ectopy when amiodarone unsuitable. Mechanism: Sodium channel blockade. Side effects: CNS effects, hypotension. Evidence: ACLS algorithms. cpr.heart.org
20) Paralytics (rare; for severe ventilator asynchrony) with full airway control
Class: Neuromuscular blockers. Dose/Time: ICU only. Purpose: Facilitate ventilation when shivering or rigidity prevents oxygenation. Mechanism: Blocks neuromuscular transmission. Side effects: Apnea; requires sedation and airway. Evidence: Critical-care protocols; not first-line. PMC
Dietary molecular supplements
Supplements do not treat hypothermia. They may support recovery and energy after rewarming in selected people. Discuss with a clinician.
1) Oral carbohydrate solutions (glucose polymers)
150-word description: After mild hypothermia, warm sweet drinks (if the person is awake, can swallow, and is not nauseated) give quick energy to power shivering and restore liver glycogen. Solutions that contain glucose or maltodextrin are easy to absorb and can be sipped while wrapped in insulation. Dose varies, typically small, frequent sips. Function: Fuel for shivering thermogenesis and brain. Mechanism: Carbohydrates enter glycolysis, generating ATP and heat; warm fluid adds small conductive heat. Do not give by mouth if confusion, vomiting, or aspiration risk. Wilderness Medicine Training Center
2) Thiamine (B1) orally after hospital care
150-word description: For malnutrition or alcohol-use disorder, thiamine can continue orally after IV dosing. Typical oral maintenance 100 mg/day (per clinician). Function: Cofactor for carbohydrate metabolism. Mechanism: Supports pyruvate dehydrogenase; reduces risk of Wernicke’s encephalopathy during high-carb refeeding. FDA Access Data
3) Magnesium (dietary replacement as indicated)
150-word description: If low Mg was found and corrected in hospital, diet or oral supplements may maintain normal levels. Dosing and need depend on labs and kidneys. Function: Muscle and nerve function; arrhythmia prevention. Mechanism: Cofactor in ATP reactions and ion channel stability. Only use under guidance because excess can harm. FDA Access Data
4) Protein with essential amino acids
Adequate protein after recovery helps rebuild muscle and immune proteins. Function: Repair and immune support. Mechanism: Provides amino acids for enzymes and structural proteins. (General nutrition guidance; clinician or dietitian can personalize.) PMC
5) Balanced electrolytes in food/fluids
Broths and balanced oral rehydration solutions support fluid and electrolyte balance after exposure. Avoid excessive free water alone. Mechanism: Restores sodium, potassium, and glucose-sodium cotransport. PMC
6) Omega-3–rich foods (dietary)
As part of heart-healthy recovery, fatty fish and plant omega-3s support cardiovascular health. Mechanism: Membrane and anti-inflammatory effects (long-term health), not acute rewarming. PMC
7) Vitamin D (if deficient)
Cold months often mean low sun. If labs show deficiency, supervised supplementation supports bone/muscle health. Mechanism: Hormone-like effects on calcium and muscle function. PMC
8) Folate/B12 (if deficient)
Treat documented deficiencies that impair energy and nerve function. Mechanism: DNA synthesis and methylation for blood and nerves. PMC
9) Complex carbohydrates (whole grains) during recovery
Provide sustained glucose for activity and thermoregulation in the days after exposure. Mechanism: Slower absorption supports steady energy. PMC
10) Warm, calorie-dense meals
Stews, soups, and warm cereals help restore energy and provide gentle heat. Avoid alcohol. Mechanism: Increases calorie intake for thermogenesis; warm temperature adds comfort. Wilderness Medicine Training Center
Drugs for immunity boost / regenerative / stem cells
There are no medicines proven or approved to “boost immunity,” “regenerate,” or act as “stem-cell drugs” to treat accidental hypothermia. Using such products for hypothermia is unsupported and potentially unsafe. Focus on rewarming, fluids, oxygen, nutrition, and treating causes/complications. If you see products making these claims, discuss risks with a clinician and check FDA resources for approvals and warnings. PMC
Procedures / surgeries (why they’re done)
1) Extracorporeal life support (ECMO/CPB)
Procedure: VA-ECMO or cardiopulmonary bypass. Why: Severe hypothermia with cardiac arrest or instability. Fastest, most effective core rewarming and oxygenation when available. PMC+1
2) Thoracic (pleural) lavage
Procedure: Warmed saline introduced and drained via chest tubes. Why: Invasive internal heat exchange when ECMO is unavailable. PMC
3) Peritoneal lavage
Procedure: Warmed dialysate in the abdomen, cycled. Why: Adds core heat where other methods are insufficient. PMC
4) Hemodialysis with warmed dialysate
Procedure: Dialysis circuit warms blood. Why: For patients with renal failure or when extracorporeal heat exchange is needed. PMC
5) Endotracheal intubation and mechanical ventilation (with warmed humidified gases)
Procedure: Secure airway, ventilate, warm inspired gas. Why: For severe hypothermia, reduced consciousness, or respiratory failure. PMC
Preventions
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Dress in layers: moisture-wicking base, insulating mid-layer, windproof/waterproof shell. Cover head/neck/hands. Wilderness Medicine Training Center
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Stay dry: pack rain gear; change wet clothes fast. Wilderness Medicine Training Center
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Block wind: use shelters, barriers, and wind shadows. Wilderness Medicine Training Center
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Fuel and hydrate: eat carbs and drink warm fluids regularly. Wilderness Medicine Training Center
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Plan and check weather: shorten trips in storms or extreme wind chills. Wilderness Medicine Training Center
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Buddy system: watch for early signs—shivering, stumbling, confusion. Wilderness Medicine Training Center
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Pack heat sources: chemical heat packs, emergency bivy/sleeping bag, insulation. Wilderness Medicine Training Center
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Avoid alcohol and sedatives in the cold: they impair judgment and heat balance. NCBI
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Protect the very young, elderly, and ill: they cool faster; keep indoor heating safe and steady. NCBI
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Prevent trauma-associated cooling: insulate injured people early; avoid prolonged exposure on cold ground. PMC
When to see a doctor (or call emergency services)
Seek urgent medical help for: worsening shivering, confusion, slurred speech, stumbling, drowsiness, pale/cold skin, very low energy, any loss of consciousness, or suspected moderate or severe hypothermia. Call emergency services if the person is not responding, breathing is slow/irregular, pulse is weak/absent, there is major trauma, or there has been submersion in cold water. Even if someone seems to “wake up,” they can still be unstable; they should be evaluated and rewarmed under monitoring. Early transfer to a center with ECMO saves lives in selected severe cases. PMC+1
What to eat and what to avoid (after rescue and during recovery)
Eat:
• Warm sweet drinks (if safe to swallow) and warm soups to give quick energy and comfort.
• Complex carbs (whole grains, legumes) for steady energy the next days.
• Lean proteins (eggs, fish, legumes) to rebuild muscle.
• Broths and balanced fluids to restore electrolytes.
• Fruits/vegetables for vitamins and minerals. Wilderness Medicine Training Center+1
Avoid:
• Alcohol (makes heat loss worse and clouds judgment).
• Large caffeine doses (can increase diuresis and jitteriness).
• Ice-cold beverages immediately after rescue.
• Heavy, hard-to-digest meals in the first hours if nauseated.
• Supplements that promise “fast immune boosts” for hypothermia—they don’t treat the condition. NCBI
Frequently asked questions
1) Can I rub cold hands/feet to warm up?
No. Rubbing can damage skin and push cold blood to the core, making afterdrop worse. Warm the trunk first and use gentle heat on armpits and chest. Wilderness Medicine Training Center
2) Should I put someone in a hot bath?
Not outside a hospital. Sudden limb rewarming can cause collapse. Use insulation and warm the trunk. Hospitals can use controlled internal methods. PMC
3) When does shivering stop?
Shivering often stops as hypothermia becomes moderate to severe, which is bad—not a sign of improvement. Seek urgent care. NCBI
4) Is cardiac arrest from hypothermia survivable?
Yes—some patients survive with good brain recovery if rapidly transported for ECMO/CPB and rewarmed under protocols. PMC+1
5) Can I give hot coffee or alcohol?
Avoid alcohol. Warm sweet drinks are fine only if the person is awake and can swallow safely. NCBI
6) Do I keep doing CPR if the patient is very cold?
If there are no signs of life, start CPR and follow local protocols; many systems continue resuscitation until the patient is “warm and dead.” Prefer transport to an ECMO center when feasible. PMC
7) What temperature is considered hypothermia?
Core temperature <35 °C (95 °F). NCBI
8) Are warm IV fluids necessary?
Yes, in moderate/severe cases or shock. Cold IV fluids worsen hypothermia. Use warmed isotonic crystalloids. Wilderness Medicine Training Center
9) Can I rewarm hands and feet first?
No. Start with the trunk to reduce afterdrop and arrhythmia risk. Wilderness Medicine Training Center
10) What about anti-shivering medicines?
In hospital, clinicians may use dexmedetomidine, meperidine, or buspirone under monitoring. These are adjuncts to rewarming, not cures. FDA Access Data+2FDA Access Data+2
11) Does everyone with hypothermia need antibiotics?
No. Antibiotics are only for proven or strongly suspected infection. PMC
12) Is targeted temperature management (TTM) the same as accidental hypothermia?
No. TTM is controlled temperature care after cardiac arrest; accidental hypothermia is unplanned cooling. Post-arrest guidelines now emphasize avoiding fever and maintaining normothermia. AHA Journals
13) Can I use heating pads directly on bare skin?
Use caution to avoid burns, especially if the person is numb. Prefer heat over insulation layers and monitor skin. Wilderness Medicine Training Center
14) Why is gentle handling so important?
A cold heart is irritable; rough movement can trigger deadly arrhythmias. Keep the person flat and move carefully. Wilderness Medicine Training Center
15) How fast should rewarming be?
Depends on severity and method. Passive/active external rewarming is slower; ECMO/CPB can rewarm rapidly. The team monitors temperature and heart rhythm continually. PMC
