Altitude Sickness: Prevention, Treatment and UK Online Doctor Guide

Altitude sickness, also known as Acute Mountain Sickness (AMS), is a condition caused by the reduced air pressure and lower oxygen levels at high altitudes. It typically affects British travellers visiting destinations such as the Alps, the Andes, the Himalayas, or even high-altitude cities like Cusco or La Paz.

As you go higher, the atmospheric pressure drops, meaning there are fewer oxygen molecules in every breath you take. If your body does not have enough time to adjust (acclimatise) to this change, it can lead to physical symptoms. While mild AMS is common and often manageable, it can progress to life-threatening conditions if the person continues to ascend despite feeling unwell.

Symptoms of altitude sickness usually develop within 6 to 24 hours of reaching a high altitude. According to NHS guidance, the feeling is often compared to a severe hangover. You should look out for:

• A persistent, throbbing headache (usually the first sign).
• Nausea or vomiting.
• Dizziness or lightheadedness.
• Fatigue and loss of energy.
• Loss of appetite.
• Shortness of breath upon exertion.
• Disturbed sleep patterns.

If you experience these symptoms, it is vital to stop ascending. If symptoms do not improve within 24 hours or if they worsen, you must descend immediately by at least 500 to 1,000 metres.

Gradual Ascent

The golden rule of high-altitude travel is to avoid flying or driving directly to high altitudes if possible. If you must, try to spend a few nights at an intermediate altitude (around 2,500m) before going higher. The NICE (National Institute for Health and Care Excellence) guidelines suggest that above 3,000m, you should not increase your sleeping elevation by more than 300m to 500m per night.

The 'Climb High, Sleep Low' Rule

This is a common technique used by mountaineers. You can hike to a higher altitude during the day to help your body adapt, but always return to a lower altitude to sleep. This gives your respiratory system time to recover and adjust.

Hydration and Diet

Drink plenty of water to avoid dehydration, which can mimic or worsen AMS symptoms. It is also advised to eat a high-calorie diet rich in carbohydrates while avoiding alcohol, as alcohol can suppress your breathing rate and worsen the effects of low oxygen.

For some travellers, especially those with a history of altitude sickness or those forced to ascend quickly due to itinerary constraints, preventative medication may be recommended. The most common treatment used in the UK is acetazolamide (often known by the brand name Diamox).

Acetazolamide works by increasing the amount of bicarbonate excreted in the urine, which makes the blood more acidic. This stimulates the brain to breathe faster and more deeply, increasing the intake of oxygen and speeding up the natural acclimatisation process. It is important to note that acetazolamide is not a 'cure-all'; it helps prevention but is not a substitute for a safe ascent rate.

In the UK, acetazolamide is 'off-label' for altitude sickness, meaning that while it is widely recognised as effective by medical professionals and following NICE clinical knowledge summaries, the manufacturer has not specifically licensed it for this use. A doctor must assess your suitability before prescribing it.

Planning a trip to a high-altitude destination can be complex, and getting the right medical advice is crucial for your safety. You should consider booking a consultation with an online doctor if:

• You are planning a trek to altitudes above 3,000 metres and want to discuss a prevention plan.
• You have previously suffered from AMS and are worried about a recurring episode.
• You have underlying health conditions, such as heart or lung disease, that might be affected by low oxygen levels.
• You wish to obtain a prescription for acetazolamide after a formal clinical assessment.

A UK online doctor service provides a convenient way to discuss your itinerary and medical history from home. They can provide evidence-based travel health advice and, where appropriate, issue a private prescription for travel medication to be collected at a local pharmacy or delivered to your door.

While most altitude sickness is mild, there are two severe forms that require immediate emergency medical intervention. These are High Altitude Pulmonary Oedema (HAPE) and High Altitude Cerebral Oedema (HACE).

HAPE

This is a buildup of fluid in the lungs. Symptoms include a persistent cough (often with frothy or pink sputum), extreme breathlessness even when resting, and a blue tinge to the lips (cyanosis).

HACE

This is a buildup of fluid on the brain. Symptoms include severe confusion, lack of coordination (stumbling or 'drunken' walking), hallucinations, and eventually loss of consciousness. Both HAPE and HACE are life-threatening and require immediate descent and hospitalisation.