Prevention of Altitude Illness for Two Day Mountain Climbs

Published:  02/26/2018

Group of climbers hiking on snow to Camp Muir

Maria Faires, RD Summit Climb with Climb For Clean Air - Mt. Rainier Hike to Camp Muir Basecamp

Altitude sickness develops when the rate of ascent into higher altitudes outpaces the body's ability to adjust to those altitudes.

Acute Mountain Sickness
Acute Mountain Sickness (AMS) is the mildest form and it's  common. The symptoms can feel like a hangover with dizziness, headache, muscle aches, nausea. This condition typically occurs at an altitude of >2500 meters (8200 feet); however, it can occur at lower elevations in high-risk individuals. Symptoms are caused by decreased amount of oxygenation of the blood and body tissues due to the reduced air pressure and lower oxygen levels at high altitudes.

Symptoms of mild to moderate acute mountain sickness may include headache plus at least one of the following:

  • Sleep disturbance
  • Dizziness or light-headedness
  • Fatigue
  • Nausea or vomiting
  • Rapid pulse (heart rate)
  • Shortness of breath with exertion
  • GI symptoms (loss of appetite, nausea, vomiting)

High Altitude Cerebral Edema and High Altitude Pulmonary Edema
High Altitude Cerebral Edema (HACE) and High Altitude Pulmonary (HAPE) are less common than AMS yet severe and potentially fatal manifestations of high altitude illness.

Those with HACE have severe AMS and will have ataxia (inability to walk straight) and  altered mental status like irritability or acting drunk. Generally, it takes 3-5 days to develop HACE after AMS.

HAPE generally occurs 2-4 days after rapid ascent to over 8000 feet. Those with HAPE will have two of these symptoms: have difficulty breathing when at rest, cough, weakness, chest congestion or tightness plus at least two of these: lung crackles, blue tongue or lips, rapid breathing, heart rate over 100.

The Lake Louise Consensus Definition for high-altitude pulmonary edema has set widely used criteria for defining High Altitude Sickness symptoms.  "The Lake Louise Consensus on the Definition of Altitude Illness"High Altitude Medicine Guide. Thomas E. Dietz. Retrieved 2012-11-10.

Two Day Climb to Above 8000 feet
Acclimatization is critical for anyone climbing above 8,000 feet but those doing only a two day climb typically don't have enough time to gradually work their way up the mountain to higher and higher altitudes to adjust. This could make them vulnerable to acute mountain sickness (AMS) which may develop at altitudes as low as 6500 feet.

A special note to climbers on Mount Rainier, Mt. Hood, Mt. Baker or other two day climbs. Climbers frequently feel the mild effects of altitude sickness, but most do not get seriously sick because they can descend to below 8000 feet before many of the medical complications arise.

What Causes Altitude Illness?
As you ascend higher into the atmosphere there is lower atmospheric air pressure pushing the air molecules together, so oxygen molecules become few and far between. The available amount of oxygen to sustain mental alertness and exercise performance per breath decreases with altitude.  Since the number of molecules (of both oxygen and nitrogen) per given volume, drops as altitude increases, you have to move larger volumes of air to get sufficient amounts. The higher the altitude, the less the oxygen saturation and risk of hypoxemia (low blood oxygen)


It is not possible to know in advance if you will become ill when traveling to a high altitude. In addition, being physically fit does not necessarily decrease your chances of developing a high altitude illness. There are certain people who are at higher risk:

  • Have a prior history of high altitude illness
  • Overexert themselves
  • Drink alcohol before adjusting to the change in altitude
  • Ascend rapidly from low elevation to sleeping altitudes above 8000 feet
  • Ascend rapidly (>500 to 1000 m /day in sleeping altitude), when over 9000 feet
  • Have a medical problem that affects breathing

Prevention of altitude illnesses will increase your chances of enjoying your experience.

These tips may help reduce your susceptibility to the effects of being at altitude:

Explore these other tips   And read these Last Minute tips Before Your Mountain Climb

If possible, spend a night at an intermediate altitude before coming to above 9000 feet to sleep.

Your symptoms will depend on how hard you exert yourself. So prepare yourself well by following a mountaineering training program for 6 months before your climb.

Your goal is to be in the best possible physical condition you can. Although physical fitness enables greater exertion at altitude, it does not protect against any form of altitude disease.

Don't over pack your backpack. Plan very well so that you have what you need but nothing redundant or extraneous. Extra weight means you will have to exert yourself more.

The week before your climb, take extra good care of yourself by eating well, hydrating with at least half your body weight in ounces of water and getting extra sleep. Don't drink alcohol the week before.

Ascend slowly.

See these Camp Muir Day Hike tips for more helpful tips.

Limit strenuous activity on the first day at altitude.

Use the rest step. Continuous movement is a great strain on your muscles. Also, stopping and starting, like slowing down and speeding up, wastes energy. The key to preserving your energy for the long haul is to be slow and steady.

The "rest step" is a technique used by mountaineers to slow their tempo, rest their muscles and conserve their energy while climbing on steep terrain at high altitudes.

Pressure Breathe. One of the goals of acclimatization is to increase ventilation (breathing) to compensate for lower oxygen volume in the air. Take slow deliberate deep breaths, use pressure breathing techniques. During your rest step, exhale forcefully through pursed lips, emptying your lungs in one big "whoosh" as if you were trying to blow out a giant candle.

Synchronize your breathing with each movement. Inhale deeply as you step up; exhale fully into the rest step.

Eat enough food and drink enough water while on your climb. Also, eat a high carbohydrate calorie diet (> 60% of your calories) while at altitude, even if your appetite is reduced. Take a variety of your favorite foods that will be appealing to you. Do a trial run of these foods in the month before your big climb so you know if these foods work well for you.

Hydration is critical. Breathing large volumes of dry air at altitude increases water loss. Drinking four to five liters of water a day is usually good but keep an eye on your urine; make sure your urine is clear and copious. If you routinely take a diuretic, tell your doctor you are doing a climb and see if they want you to continue or if you can discontinue for a few days.

Avoid tobacco, alcohol and other depressant drugs including, barbiturates, tranquillizers, sleeping pills and opiates.

Your guides are experienced in identifying altitude sickness and knowing what to do so let them know how you are feeling.

If you begin to show symptoms of moderate altitude sickness, don't go higher until symptoms decrease. If symptoms increase, descend. Let your guides and team members know how you are feeling.

Keep your temperature regulated. Wearing warm clothes is important as it allows you to conserve energy that would otherwise be spent on maintaining your body temperature. But don't allow yourself to get too warm. Learn how to properly layer your clothes so they wick moisture away from you.

Treatment of mild AMS: Tylenol (Acetaminophen) 650 mg to 1 gm by mouth every 6 hours as needed until symptoms improve or Motrin (Ibuprofen) 200 mg 1 tab every 4-6 hours and do not exceed >6 tabs per 24 hours.

There are more medications that are used in the prevention and treatment of high altitude illness and you can find out more about those from Wilderness Medicine Society Clinical Practice Guidelines 2019 Update. Please discuss the use of these meds with both your guide company and your physician as there can be serious side effects.

Acetazolamide (Diamox) is a medication sometimes used for prevention of acute mountain sickness (AMS), Talk with your mountain guide service ahead of time and your doctor to see if Acetazolamide prophylaxis is right for you. Consider medical prophylaxis if you have had a history of prior AMS.

There is no reliable scientific evidence for Gingko Biloba at this time but some believe that 100 mg by mouth twice daily started 3-5 days prior to ascent then continued for 2-3 days at maximum sleeping altitude is beneficial.  If you decide to try it, do a trial run first a month before to make sure you react okay with it. And always inform your doctor or pharmacist if you are taking other medications to avoid a drug interaction.

Maria Faires, RD is a mountaineering fitness and nutrition expert. 

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