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Altitude Sickness: Symptoms, Treatments, Prevention

Dr Karen Martin
Reviewed by Dr Karen MartinReviewed on 12.03.2025 | 4 minutes read
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Altitude sickness is also known as acute mountain sickness. Altitude sickness can happen to anyone, no matter your fitness level, age or experience. It affects your breathing and your ability to take in oxygen. This can be life-threatening. It happens when you travel to a higher altitude too quickly, typically greater than 2500 m (about 1.5 miles) above sea level, often when mountain climbing, but also in cities that sit high above sea level. 

What are the symptoms of altitude sickness?

Symptoms usually develop within 6 to 24 hours of reaching the 2,500m altitude level and initially feel like a bad hangover so you may feel:

  1. Headache – Often one of the first and most noticeable signs, it can be mild or intense.
  2. Nausea and Vomiting – The lack of oxygen can disrupt the stomach, leading to nausea, and sometimes vomiting.
  3. Dizziness – A feeling of lightheadedness or imbalance can occur due to the body's difficulty adjusting to the altitude.
  4. Fatigue – You may feel unusually tired, even after minimal physical exertion.
  5. Shortness of Breath – Breathing may become more difficult as oxygen levels decrease with altitude.
  6. Loss of Appetite – Many people experience a reduced desire to eat when dealing with altitude sickness.
  7. Swelling – Mild swelling of the face, hands, or feet can sometimes occur, especially during the first few days at high elevations.

Treatments for Altitude Sickness

The treatment for altitude sickness primarily focuses on preventing symptoms from worsening and helping the body acclimatize to high altitudes. Here are the most common treatments and approaches:

1. Descend to a Lower Altitude

The most effective treatment for altitude sickness is descending to a lower altitude as soon as symptoms appear. Even a descent of 1,000 to 2,000 feet (300 to 600 meters) can bring relief. This helps the body adjust and allows oxygen levels to increase.

2. Rest and Hydration

Rest is crucial to allow your body time to adjust to the reduced oxygen levels. Staying hydrated also helps alleviate symptoms, as dehydration can worsen altitude sickness. Drink plenty of fluids, but avoid alcohol and caffeine, as they can contribute to dehydration.

3. Oxygen Therapy

In cases of moderate to severe altitude sickness, supplemental oxygen can be administered to provide immediate relief by increasing oxygen levels in the bloodstream. This is particularly helpful in situations where quick descent isn’t possible.

4. Medications

  • Acetazolamide - This is the most commonly prescribed medication to prevent and treat altitude sickness. It helps your body acclimatize by stimulating breathing and improving oxygenation. It's often recommended for people travelling to higher altitudes.
  • Ibuprofen or Aspirin - These can be used to relieve headaches and body aches associated with altitude sickness.
  • Antiemetics - These may be used to control nausea and vomiting.

5. Avoid Further Ascent

If you experience symptoms of altitude sickness, it’s essential not to ascend any higher until symptoms have resolved. If symptoms persist, continue to descend to a lower elevation and seek medical advice.

6. Hyperbaric Chambers

In some cases, particularly in remote areas where descent isn't immediately possible, hyperbaric oxygen therapy may be used. These chambers simulate a lower altitude by increasing the pressure and delivering higher oxygen levels to the body. This can be a life-saving option if descent is delayed.

7. Gradual Acclimatization

Prevention is key, and acclimatization is the most effective strategy. If you're planning to ascend to high altitudes, it’s important to take it slow. This means spending several days at intermediate altitudes before continuing to higher elevations. This allows your body to adjust gradually to the reduced oxygen levels, minimizing the risk of altitude sickness.

8. Portable Altitude Chambers

For severe cases, portable altitude chambers, which are pressurized bags, can simulate lower altitudes and provide relief until medical help is available or descent is possible.

In all cases, immediate medical attention is necessary if symptoms are severe or don't improve with the above treatments. Suppose you suspect someone has severe altitude sickness. In that case, it's important to act quickly, as untreated cases can lead to life-threatening conditions like high-altitude pulmonary edema (HAPE) or high-altitude cerebral edema (HACE).

Can I prevent altitude sickness?

Of course, avoiding traveling to altitudes of 2,500 m (1.5 miles) above sea level is one way of preventing altitude sickness. But if you can't avoid it, it's important that you do not fly directly to these levels but climb them slowly (500 m at a time, or 1/3 of a mile) over 24 to 48 hours to allow your body time to adjust.

Drink plenty of water throughout your journey and avoid strenuous exercise. Be sure to incorporate time for an appropriate amount of rest, and avoid smoking and drinking alcohol, or taking medications such as sleeping tablets.

What are the complications of altitude sickness?

Altitude sickness can lead to life-threatening conditions that can affect the brain or lungs.

High altitude cerebral edema occurs when a lack of oxygen causes the brain to swell. People often don't realize they are very unwell, and symptoms can develop very quickly. It includes symptoms like headache, nausea, weakness and confusion.

High altitude pulmonary edema is when fluid builds up in the lungs. This takes a few days and can also lead to death. Symptoms include difficulty breathing, chest pain, persistent productive cough and tiredness.

There are prescribed medications such as dexamethasone or nifedipine that can help with the symptoms of either of these – they should be taken sooner rather than later. It is always important to seek medical attention as soon as possible.

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This article has been written by UK-based doctors and pharmacists, so some advice may not apply to US users and some suggested treatments may not be available. For more information, please see our T&Cs.
Dr Karen Martin
Reviewed by Dr Karen Martin
Reviewed on 12.03.2025
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