Altitude sickness, also known as acute mountain sickness (AMS), occurs when your body cannot obtain sufficient amounts of oxygen from the air that you breathe to allow normal bodily functions. As the altitude increases, the percentage of oxygen in the air reduces, making any physical problems one may be experiencing even more severe.
Altitude sickness can affect anyone and there are no specific factors such as age, sex, or fitness level that enable you to know if you are likely to suffer. Most trekkers can go up to 2500m to 3000m with little or no problems. If you have experienced altitude sickness previously, then under similar conditions you are likely to experience altitude sickness again.
Every year trekkers spoil their holiday because they do not listen to their bodies. With a sensible approach, trekking at higher altitudes is not dangerous and is not uncomfortable as altitude sickness is largely preventable. If you experience any physical discomforts that you think could be related to altitude sickness, please inform your guide. Our guides have experience with altitude sickness, and it is important that you listen to their advice so that we can minimise any symptoms.
Symptoms of altitude sickness
Mild and common symptoms include headaches (also a symptom of dehydration), low appetite, and restless sleep. More moderate symptoms include vomiting, fatigue, and diarrhoea. Many compare altitude sickness to the sensations of having a hangover. Severe symptoms include blue lips and fingernails, severe difficulty breathing, poor coordination, fatigue, and drowsiness.
Preventing and treating altitude sickness
Symptoms often manifest themselves six to ten hours after ascent and generally subside in one to two days, but they occasionally develop into more serious conditions. If you begin to show symptoms of moderate altitude sickness, do not go higher until symptoms decrease and consider reducing your altitude. If you ascend with moderate symptoms, your problems will remain and are likely to become more severe.
The body takes time to acclimatise and get used to the low levels of oxygen in the air. We build acclimatisation days into our treks so that on certain days you will be allowed to just rest or trek in the surrounding area and at the same elevation. We also sleep in the same tea lodge, and thus altitude, for a second night. This gives your body time to get used to the thinner air.
Avoiding strenuous activity
Strenuous activity induces altitude sickness. Therefore, if you have symptoms that cause you to experience discomfort, we recommend that you minimise your strenuous activity. Make sure that you minimise the weight in your backpack (the porters will be able to take this for you), and do not participate in optional side treks to glaciers, for example.
Stay hydrated and do not drink alcohol. Alcohol causes dehydration and exacerbates symptoms of AMS. Remember to consume sufficient water and salt via food or rehydration powder. For homemade rehydration drinks, we recommend Sprite and salt as both are readily available in the mountains.
Medicine: Diamox or Acetazolamide
Diamox or Acetazolamide (generic equivalent) tablets are widely used by trekkers. They help the body to adjust to increased levels of carbon dioxide due to the higher altitude. As recommended by the NHS, a dosage of 125mg to 250mg twice daily starting two days before the trek is generally appropriate. Once you have reached your highest altitude, you should continue the dosage for 3 days.
For low altitude treks such as the Poon Hill Trek, Diamox is not required. For the Everest Base Camp Trek, it is highly recommended that you take Diamox as per the instructions above. For other treks around 4000m altitude, you should either take Diamox as recommended above or when you believe you sense any possible minor altitude sickness symptoms.
Diamox can be easily purchased in Kathmandu and we can take you to the pharmacy when you arrive. Alternatively you can get Diamox from your doctor, or at the Nomad travel store in the UK. It is often cheaper and easier to purchase Diamox or Acetazolamide in Kathmandu.
Everest Base Camp: Medical access and air ambulances
The Himalayan Rescue Association provides medical clinics with highly experienced doctors that specialise in altitude sickness and general injuries, as well as providing general medical care to the local community. Clinic locations are:
1) Everest Base Camp - open during the climbing season of April and May.
2) Pheriche - a town on the Everest Base Camp trail; open during the trekking season.
Depending on the location, a doctor can also visit a sick or injured trekker, if he or she is unable to visit the clinic. For severe cases, an air ambulance will take trekkers to a hospital in Kathmandu where they will receive all the necessary care and attention required for their recovery. It is important to ensure that all trekkers have travel insurance that covers air ambulances.
Small pharmacies exist in many areas. Access to basic medicine is available, especially if you are struggling with altitude sickness and are not taking Diamox or Acetazolamide.
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