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  • What is Altitude Sickness?

    It’s the inability to get enough oxygen to be able to function properly at high attitude. It is separated into 2 different conditions, mild, and severe altitude sickness.

  • What causes Altitude Sickness?

    It occurs when you climb levels higher than 2500m or 8250ft above sea level.

    The higher you go up, the lower atmospheric pressure gets. This makes it difficult for you to get the oxygen you need to function properly.

  • What are the symptoms of Altitude Sickness?

    Altitude symptoms present 6 to 24 hours after you start going up in altitude to levels 2500m above sea level.

    Symptoms of mild altitude sickness include

    • Headache
    • Nausea
    • Dizziness
    • Exhaustion
    • Increased heart rate
    • Shortness of breath
    • Loss of appetite
    • Difficulty in sleeping
    • Feeling unwell

    If left untreated then they can become worse and develop into severe altitude sickness.

    Severe Altitude Sickness is rare but it it's important to be aware of symptoms as they indicate there may be a build-up of fluid in the brain and/or lungs. This can be potentially life threatening.

    This is also sometimes referred to as HACE or High Altitude Cerebral Oedema. The lack of oxygen causes the fluid to leak out from the blood vessels and cause swelling around the brain.

    It has a tendency to occur if altitude is ascended very rapidly or if you are staying at very high altitude for a week or more.


    Symptoms to look out for include


    • Worsening of the mild altitude symptoms described above
    • An irritable persistent cough
    • Double vision
    • Cough up a pink/white liquid frothy
    • Drowsiness
    • Confusion
    • Fits
    • Convulsions
    • Irrational behavior
  • What can make Altitude Sickness worse?

    Ignoring the signs and symptoms and continuing to ascend to higher levels. This can make mild symptoms into severe cases of altitude sickness.

  • How do I prevent Altitude Sickness?

    Ascend slowly and gradually when you get to altitudes above 3000m. This will give your body time to adapt.

    As a general guide, the altitude you sleep at should not increase by more than 300 to 500m at a time.

    Give your body 3-4 days to adapt before you start to ascend to higher levels and try to avoid flying in direct to high levels.

    You are less likely to suffer from altitude sickness if you are trekking and sleeping in lower valleys at night compared to climbing a big summit like Everest.

    You can also use medication to prevent altitude sickness. See below

  • What medication can I take to prevent/treat Altitude Sickness?

    Acetazolamide is a versatile medication, which has several applications. It is a popular and widely used treatment for the prevention or reduction for the symptoms of altitude sickness. Acetazolamide actively reduces the feelings of dizziness, nausea, headaches and shortness of breath that are associated with rapid ascents.

    Acetazolamide is usually taken one to two days before you begin ascending. You continue taking it every day, finishing two days after the highest altitude has been reached.

    Acetazolamide corrects the chemical imbalance that occurs when altitudes are climbed too rapidly. It increases the volume of urine produced and alters the acidity of the blood, which lowers the fluid content found in and around the brain and lungs.

    If the correct procedures are followed, the effects of altitude sickness will normally subside in approximately 1-2 days. Taking Acetazolamide 250mg tablets, in conjunction with following the correct procedures, has shown to cut recovery time in half.

    A person’s breathing patterns can by significantly altered when sleeping at high altitudes. Usually, the altered pattern is characterized as rapid, short breaths that are followed by prolonged pauses. This is considered normal and is not classed as being dangerous. However, it can result in poor quality sleep. Taking Acetazolamide has shown to improve this breathing pattern, which allows for a much better nights sleep.

    They should not be used as a substitute for sensible acclimatisation

  • Do I need to see a doctor for Altitude Sickness?

    Mild cases of altitude sickness can be treated with rest, acclimatization and medication. When the symptoms have subsided it is usually fine to continue to ascend.

    Severe cases of altitude sickness need medical attention and you need to descend to lower levels as soon as possible

Authored By:

A photo of  Leanne Sinclair

Leanne Sinclair


Published on: 29-05-2019

Last modified on: 29-05-2019

Leanne is a clinical pharmacist with years of experience working in pharmacy.

Reviewed By:

A photo of  Chris Newbury

Chris Newbury

BPharm IP

Reviewed on: 29-05-2019

Next review date: 29-05-2021

Chris is a vastly experienced clinical pharmacist and has been registered as an Independent Prescriber since 2014.

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