High-altitude sickness prevention medication

High-altitude sickness is a general term for unique brain and lung syndromes that can occur in people who ascend to a high altitude, generally above 6,000 to 8,200 feet (2,000 to 2,500 meters), or go higher while already at high altitude.

Here are the three main types of altitude sickness:

• Acute mountain sickness – This is the most common type. It causes symptoms like those of a hangover from drinking too much alcohol.
• High-altitude cerebral edema (“HACE”) – This is less common but more serious than acute mountain sickness. It involves swelling of the brain.
• High-altitude pulmonary edema (“HAPE”) – This is also less common and more serious than acute mountain sickness. It involves fluid buildup in the lungs.

High-altitude sickness is mainly caused by low air pressure and a lower oxygen level at higher altitude. Other things, such as cold air, may be factors too. The faster you climb to high altitude, the greater your chance of developing symptoms.

Altitude illness can present three different ways, depending on its severity. We will briefly discuss the symptoms of each of type of high-altitude sickness [1] High Elevation Travel & Altitude Illness https://wwwnc.cdc.gov/travel/yellowbook/2024/environmental-hazards-risks/high-elevation-travel-and-altitude-illness here.

Acute Mountain Sickness

When it occurs

Symptoms develop within one day of traveling to high altitude.

Symptoms:

• Headache
• Fatigue
• Dizziness
• Trouble sleeping
• Nausea with occasional vomiting
• Shortness of breath with activity

High-altitude cerebral edema (HACE) (brain swelling)

When it occurs

Symptoms usually begin one to three days after traveling to high altitude.

Symptoms:

• Confusion
• Trouble walking
• Extreme fatigue

High-altitude pulmonary edema (HAPE) (fluid buildup in the lungs)

When it occurs

Symptoms usually begin two to four days after traveling to high altitude.

Symptoms:

• Coughing
• Feeling of shortness of breath

To assess someone’s risk for developing high-altitude sickness, [3] Travel to High Altitudes https://wwwnc.cdc.gov/travel/page/travel-to-high-altitudes a few things must be considered:

• Type of trip: how high and how fast the ascent will be
• History of high-altitude symptoms
• Underlying medical conditions that can predispose to high-altitude sickness

Let’s talk about each of them in more detail.

Type of trip

A rapid ascent without adequate time for acclimatization will increase the chance of high- altitude disease.

History of high-altitude symptoms

A person who has had high altitude illness is more likely to develop it again.

Medical conditions that increase the risk

Relatively few conditions predispose someone to high-altitude disease:

• Neuromuscular diseases
• Lung disease, such as moderate or severe COPD
• Severe heart conditions (ischemic heart disease)

Common medical conditions such as high blood pressure and diabetes are not considered risk factors.

Ascending gradually to a high altitude is the best way to prevent high-altitude illness. But sometimes medication is necessary as a form of prevention.

No medication is advised

• Ascending to an altitude of less than 2,800 meters (9,200 feet)
• From a low altitude, taking at least two days to arrive at 2,500 to 3,000 meters (8,200 to 9,800 feet) AND, in either case:
• No history of altitude illness

Medication is advised

• History of high-altitude sickness
• Ascending to (and sleeping at) more than 500 meters (1,640 feet) a day above 3,000 meters (9,800 feet)
• Ascending to 3,500 meters (11,500 feet) in less than two days
• Medical condition that predisposes to high-altitude sickness

High-altitude medications [2] EMS High-Altitude Field Prophylaxis And Treatment https://www.ncbi.nlm.nih.gov/books/NBK560677/ can be given for prevention or treatment. Here we will discuss high-altitude medication only for the simplest and most common type of high-altitude illness, acute mountain sickness.

Prevention

• Acetazolamide (Diamox) 125 mg twice a day. Start two days before ascending and take while ascending and one day after reaching the peak. This is the most commonly used medication.
• Dexamethasone 4 mg every 12 hours. Start the day of ascent and take while ascending and until two days after reaching the peak. Should not be continued for longer than seven days. This medication is not commonly used for prevention purposes.

Treatment

• Acetazolamide (Diamox) 250 mg twice a day. Continue for two days or until symptoms resolve.
• Dexamethasone 4 mg every 12 hours. Continue for two days or until symptoms resolve.

Like any other medication, acetazolamide (Diamox), the most commonly prescribed altitude-sickness medication, has potential side effects. In the table below we will describe the most common side effects and the likelihood of getting them.

Numerous chemical agents and methods are purported to help with high-altitude sickness, [4] Altitude sickness https://www.nhs.uk/conditions/altitude-sickness/ including taking certain supplements and ingesting certain plant parts. But no high-quality studies support any of these treatment options.

Supplements

• Antioxidants
• Iron
• Dietary nitrates
• Salicylic acid
• Forced overhydration
• Over-the-counter oxygen canister

Plants

• Some local Andean populations use coca to enhance physical performance at high altitude, but no formal studies have been done to confirm that this works.
• If you’re considering coca as a high-altitude sickness treatment, use coca leaves (which have a high-cocaine alkaloid that may slightly increase exercise tolerance), not coca tea.
• We do not recommend chewing coca leaves to prevent high-altitude illness.

High-altitude illness usually occurs in areas over 8,000 feet (2,500 meters), with some exceptions.

The condition is commonly reported in the following places:

• Himalayas (Nepal)
• Andes
• Rocky Mountains
• Alps
• Caucasus (Armenia, Georgia)
• Everest Base Camp
• Annapurna Circuit
• Mount Kilimanjaro (Tanzania)
• Inca Trail (Peru)
• Aconcagua
• Mount Kinabalu (Malaysia)
• Mount Fuji (Japan)
• Ethiopia
• South Africa
• Cities of Lhasa, La Paz, Quito, Cuzco, Machu Picchu, Bogotá

The higher the altitude, the higher the chance of developing high-altitude sickness symptoms.

In the table below, you can find the approximate risk, based on altitude alone, of any of these three common forms of high-altitude sickness:

• Acute mountain sickness (AMS)
• High-altitude cerebral edema (HACE), or brain swelling
• High-altitude pulmonary edema (HAPE), or fluid buildup in the lungs

Some people are advised to undergo a medical consultation before going to high-altitude areas because some preexisting conditions may increase the likelihood of developing altitude sickness and related complications.

The table below categorizes certain conditions as low, moderate, or high risk for high-altitude illness and/or worsening of a preexisting condition because of the high altitude.

People who exercise regularly, especially at high intensity, are more likely to have the capacity to climb.

Some behaviors can decrease the chance of getting high-altitude sickness.

Gradual ascent

Gradual ascent is one of the surest and safest methods of preventing high-altitude illness.

• As a rule, people who normally reside below an elevation of 1,500 meters (5,000 feet) should avoid abrupt ascents to a sleeping altitude above 2,800 meters (9,200 feet). This can be accomplished by sleeping at an intermediate altitude for one night.
• If you ascend to above 3,000 meters (9,800 feet), it is advisable to not spend the next night at an elevation more than 500 meters higher.
• Resting one day for every 1,000 meters (3,200 feet) in elevation is advised.

The common saying among mountaineers is climb high, sleep low.

Alcohol and drug avoidance

Alcohol and sedatives should be avoided during the acclimatization process, especially during the first two days.

Diet and hydration

Studies on high-carbohydrate diet and vigorous hydration (beyond the normal amount required) have not shown them to reduce the likelihood of altitude sickness.

Exertion

Vigorous exertion can contribute to high-altitude symptoms, while moderate exercise can improve them.