Part 2: Mountaineering Medical Issues

Every Denali climber should be familiar with both prevention and proper treatment of the most common medical ailments seen on Denali, namely Acute Altitude Sickness (AMS, HACE, HAPE), Frostbite, and Gastrointestinal Illness. The following recommendations were derived from a panel of Wilderness Medical Society experts.

Physician seated in a tent next to a patient wearing anoxygen mask
Altitude Illness can be usually be avoided with proper acclimatization.  (NPS Photo/Ian Shive)



Gradual ascent A highly effective means of preventing acute altitude illness is gaining no more than 500 meters (approximately 1,600 feet) in elevation per day (sleeping altitude) and including a rest day every 3 to 4 days.

Acetazolamide (Diamox) This medication has been shown to help prevent AMS when taken at a dose of 125 mg twice per day at the time of mild AMS symptom onset. Diamox requires a prescription from a physician and climbers with a known sulfonamide allergy should consider a supervised trial before using in a remote setting.

Adequate hydration/nutrition Maintaining adequate fluid and food intake does not directly prevent acute altitude illness. Instead, adequate hydration and nutrition is important in helping climbers' function well at altitude and preventing the onset of symptoms of dehydration and malnutrition that can mimic symptoms of AMS.

Signs, Symptoms, Treatment

Acute Mountain Sickness (AMS)
Signs/Symptoms Headache with one or more of the following:
  • Nausea
  • Anorexia (loss of appetite)
  • Fatigue at rest
  • Insomnia (inability to sleep)
  • Discontinue ascent until symptoms resolve
  • Maintain adequate hydration/nutrition/activity level
  • Consider acetazolamide (Diamox) at a dose of 250 mg twice per day
  • Consider pain medication for headache

High Altitude Cerebral Edema (HACE)
  • Ataxia (difficulty walking)
  • Headache (may not be present)
  • Mental status changes (disorientation, irritability, or combativeness)
  • Neurological changes (vision disturbances or seizures)
  • Descend immediately to elevation where symptoms resolve
  • Consider dexamethasone (Decadron) at a dose of 8 mg once, then 4 mg every 6 hours

High Altitude Pulmonary Edema
  • Shortness of breath at rest
  • Fatigue out of proportion with effort
  • Persistent cough (dry early, productive later)
  • Pale or cyanotic (bluish) skin color
  • Descend immediately to elevation where symptoms resolve
  • Consider nifedipine (Procardia) at a dose of 30 mg (sustained release)


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Frostbite injuries to the hands can be life-changing.
Frostbite injuries to the hands can be life-changing.  NPS Photo



Maintain peripheral perfusion/circulation

  • Maintain core body temperature
  • Maintain adequate hydration
  • Cover exposed skin
  • Minimize blood flow restriction with constrictive clothing/footwear
  • Do not tolerate numbness -- actively re-warm extremities


  • Physical activity elevates core/peripheral temperatures and can be protective against cold injury

Protection from cold

  • Avoiding perspiration as moisture hastens the effects of cold/wind
  • Increase clothing insulation layers
  • Consider chemical hand/foot/core warmers
Signs, Symptoms, Treatment
Superficial Frostbite (1st and 2nd degree)
  • Numbness
  • Erythema (redness of the skin)
  • Blanching (whitening of the skin)
  • Firm skin
  • Mild swelling
  • Blisters (clear, milky fluid)
  • Thaw promptly (skin-to-skin re-warming)
  • Protect from re-freezing
  • Never massage or use radiant heat to re-warm
  • Consider pain medication
  • Protect with dry, loose dressings
  • Consider aspiration of tense blisters (clear, milky fluid) that are likely to rupture
Deep Frostbite (3rd and 4th degree)
  • Cold
  • Pale skin appearance
  • May be frozen hard
  • Blisters (hemorrhagic or blood-filled)
  • Thaw promptly (circulating warm water bath 37-39 C)
  • Protect from re-freezing
  • Never massage or use radiant heat to re-warm
  • Consider pain medication
  • Protect with dry, loose dressings
  • Do not aspirate/debride blisters of this severity (hemorrhagic or blood-filled)


Gastrointestinal illness is another frequent complaint of expedition climbers throughout the world. The best way to prevent a digestive tract illness is through proper sanitation practices. The National Park Service mountaineering rangers work diligently to maintain a clean mountain environment through education and policy enforcement. Each climber and their team are expected to adhere to the policies outlined on this website and presented at the climber orientations in Talkeetna.
The single best way to combat the spread of gastrointestinal illness is through frequent hand washing and maintenance of personal hygiene. This is best accomplished with traditional soap and water and with alcohol-based hand sanitizers. These products should be utilized frequently especially before cooking and after using the restroom.


For additional information on these and other mountaineering-related medical issues, see the Mountain Medicine section of our Recommended Reading List.


  • Wilderness Medical Society Consensus Guidelines for the Prevention and Treatment of Acute Altitude Illness, Luks et al, 2010
  • Wilderness Medical Society Consensus Guidelines for the Prevention and Treatment of Frostbite, McIntosh et al, 2011

Last updated: December 29, 2023

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