High Altitude sickness Information

High Altitude sickness while trekking in Nepal starts to affect us from 1500 to 2000 meters upwards. As you ascend higher, the air pressure gets lower and the air gets thinner. This means that the amount of oxygen decreases and with every breath you take, we intake less oxygen in our body. Altitude sickness, not a big issue while trekking. Our body can adjust to these higher altitudes sickness, but only if given enough time. Being in a hurry in the mountains of Nepal can be life-threatening. Thus, you are better off taking it slowly along with the use of preventive medication and acclimatization.

How to prevent from Altitude sickness


Acclimatization is one of the important aspects while trekking in Nepal. Acclimatization is the word used to describe the adjustments of your body makes as it ascends. Acclimatization help individual to adjust to a change in its environments such as altitude, temperature and humidity. In almost every trekking in Nepal, you will have 2-3 rest days depending upon the length of treks which is basically for acclimatization. 40%-50% of people get altitude sickness upon trekking to 4,000m in Nepal. As a result of growing awareness of altitude problems to ensure a safe trek, there is only one death in Nepal out of every 30,000 trekkers. Even these deaths would be avoidable if everyone knew how to respond to AMS.

What to do for Acclimatization?

  • Above 2,500 meters, you should limit your daily ascent to 500 meters between night stops
  • You should have a rest day every 3 days or after 1,000 meters.
  • You should drink at least 4 litres of fluid every day. ORS is highly recommended. You will be urination much more frequently with or with drinking 4 litres of water. So it is very important to keep your body hydrated.
  • Consume a sufficient amount of carbohydrates like bread, pasta, and potatoes before and throughout your trek which minimizes the symptom of high altitude sickness

What not to do for acclimatization?

  • Do not continue ascent with a headache or any other sigh of altitude illness.
  • Avoid alcohol at all costs.
  • Do not take sleeping pills, period.
  • Avoid sleeping during the day and stay active.
  • Avoid heavy exertion.
  • Do not climb rapidly or go too far too fast. It is better to climb at a low pace.

As we go to higher altitude our bodies start to adapt the surrounding by breathing faster and deeper. Our bodies also start to produce more red blood cells to carry more oxygen, though this takes time and depends on a wide variety of factors. Thus is very important to listen carefully to what your body is telling you and help your body by doing your part.

  • Your body will increase the pulse rate and breathing rate/depth. Given that your heart is already working harder, do not push it by exerting yourself.
  • Your body will let go of non-vital fluids by increasing urination. Do your part by replenishing the fluids.
  • Your body will thicken blood through fluid loss and increase red cells production. This increased the danger of internal blood cloths. Do your part by drinking enough and remaining active during the day
  • Your body might go through a phase of periodic breathing which will disturb sleep. This is normal. Do your part by not suppressing the response through sleeping pills.
  • However, nothing will acclimatize you above 5,500 meters so limit the length of stay and/or use supplemental oxygen.

Types of Altitude Sickness and their symptoms

In we move upward into higher altitudes too quickly we start to suffer from oxygen deprivation in the form of Acute mountain sickness, HACE or HAPE. It is very important to be aware of some of the symptoms surrounding high altitude trekking.

Acute Mountain Sickness

Acute Mountain sickness is basically a bloody hangover which will show after your ascend to an altitude your body isn’t comfortable with. A hangover may be an actual hangover or dehydration or possibly a lack of essential salts. Fatigue and dizziness can be the result of exhaustion or exposure or it can be a warning shot. That is why one must have enough water/ORS and avoid alcohol. One can take Mild analgesic (paracetamol or ibuprofen) or antiemetic (ondansetron) medicines if needed. It is good to stop ascent and rest and wait for the symptoms to resolve. AMS is that much easier to come to terms with the one you have ruled out confounding causes through proper prevention.

Acute mountain sickness (AMS) common symptoms

  • Headache
  • poor appetite and nausea
  • lightheartedness
  • Vomiting and fatigue (feeling tired)
  • Dizziness
  • Insomnia/sleep disturbance
  • Swelling of hands, feet and face etc
  • Constant rapid pulse

Many people trekking will experience some form of AMS. The important thing to note is that if the symptoms are getting worse or not? If the symptoms are getting worse than it is very important to descend back 500m-1000m in altitude until acclimatization occurs.

High Altitude Cerebral Oedema (HACE)

In extreme cases, severe AMS can quickly progress to HACE.HACE causes brain swelling and can kill very quickly if not attended within one hour of developing HACE symptoms.

Common symptoms of HACE

  • Severe headache and mood changes (angry, laziness)
  • Clumsiness increase
  • Feeling confused
  • Blurred vision
  • Constant vomiting

If a person exhibits the above symptoms and cannot perform routine test like touching a finger to their nose with their eyes closed or simple arithmetic than one should descend the person immediately to a lower altitude, at least 1,000 meters. Give cylinder oxygen or use a pressure bag and give 8 mg dose of dexamethasone or acetazolamide treatment if available followed by 4 mg every 6 hours. Continue to descend.

High altitude pulmonary Oedema (HAPE)

HAPE means fluid collection in the lungs and it is fatal, much more than AMS and HACE. Typically HAPE develops when symptoms and signs of HACE worsen.

Common symptoms of HAPE

  • Trouble breathing
  • Coughing/ Feeling tired
  • Froth in saliva or spit
  • Blood in saliva or spit lips
  • Tongue or nails become blue

If the person is having difficulty in catching their breath or breathless even when resting and can hear a crackling sound from their chest than one must treat these symptoms seriously. Descend the person immediately at least 1000 meters and give cylinder oxygen or use a pressure bag if available. Give Nifedipine or acetazolamide treatment if available and continue to descend.

For safety measures on high altitude treks, Lapha holidays always carry Portable Altitude Chamber (a life-saving device in case of AMS). All our group leaders/guides are well trained in Wilderness First Aid Course to identify any symptoms and take immediate action on the spot. Our guide will provide you daily health checklist, which consists of checking your pulse rate, blood oxygen saturation level, assessing your acclimatization status using the Lake Louise system. Lapha Holidays guides are highly proficient in working at altitude and know how to take care of our client.