Altitude sickness, also known as acute mountain sickness (AMS), is a condition that can affect individuals who ascend to high altitudes too quickly, typically above 2,500 metres. At these elevations, the air contains less oxygen, which the body may struggle to adapt to, especially if there hasn’t been sufficient time for acclimatisation. This lack of oxygen can lead to a range of physiological responses, often beginning within a few hours of arrival at high altitude. Altitude sickness can affect anyone, regardless of age, fitness level, or previous exposure to altitude, although susceptibility varies from person to person. In more severe forms, altitude sickness can progress to life-threatening conditions such as high-altitude cerebral oedema (HACE) or high-altitude pulmonary oedema (HAPE).

Symptoms of altitude sickness typically begin with a headache and can develop into a broader range of discomforts if ignored. Common symptoms include nausea, dizziness, fatigue, loss of appetite, and difficulty sleeping. Breathing may become more laboured, even at rest, and some individuals experience swelling of the hands, feet, or face. As the condition progresses, symptoms may worsen and include confusion, unsteadiness on the feet, and a persistent cough, which could indicate a more serious complication such as HAPE or HACE. These severe manifestations require immediate descent and medical attention. Monitoring symptoms closely during altitude exposure is crucial to prevent complications.

The primary treatment for altitude sickness is to descend to a lower elevation as soon as symptoms begin, even if by a few hundred metres, as this often results in rapid improvement. Mild cases can be managed by resting, avoiding further ascent, and staying well-hydrated. Over-the-counter painkillers such as ibuprofen or paracetamol can help relieve headaches, while anti-sickness tablets may reduce nausea. The prescription medication acetazolamide (Diamox) can aid acclimatisation and is sometimes used preventatively or as treatment; it is generally suitable for adults and children over 12, though a doctor should always be consulted prior to use, especially in younger individuals. In more serious cases, oxygen therapy or evacuation to a lower altitude is essential. Gradual ascent and rest days are the best preventive strategies, particularly for children, older adults, or those with underlying health conditions.

Most treatments for altitude sickness are well tolerated when used appropriately, but they are not without potential side effects. Acetazolamide, for instance, can cause tingling sensations in the fingers and toes, increased urination, and altered taste, particularly a metallic taste in carbonated drinks. Some individuals may also experience gastrointestinal upset or drowsiness. Non-prescription treatments like ibuprofen or paracetamol may occasionally cause stomach irritation or, with prolonged use, affect liver or kidney function. Oxygen therapy is generally safe, though misuse of portable oxygen canister systems without proper guidance may lead to dependency or a false sense of security. As with all medications, especially in children or those with existing medical conditions, professional medical advice should be sought to balance benefits and potential risks.