Changing time zones knocks people, add the stress of winding up at work and many people arrive feeling slammed, needing a holiday. This is the time you are most likely to get sick; try to take it easy, and definitely take multi-vitamin tablets. If travelling from America the flights are particularly long with annoying stopovers and a brutal time change; we recommend arriving a day earlier to recover. For India if the trek begins in Leh then fly up there one day earlier.
It's okay to get altitude illness, but it's not okay to die from altitude illness. Trekking in the Himalayas brings people to high altitude for longer periods of time than in most other situations, and the risk of dying from altitude sickness is consequently higher in this region. Trekking in Himalayas affords the opportunity to acclimatize gradually.
Human bodies have built-in adjustment mechanisms that can optimize performance at altitudes. This process is known as acclimatization. The power of acclimatization can be demonstrated by the following examples. If a person were transported suddenly to the summit of Mt.Everest (29,128 feet; 8848 mts.), person would lose consciousness in a few minutes, and most likely die within an hour or two due to acute hypoxia. However, over 60 people have climbed to the summit of Mt.Everest without using supplemental oxygen after acclimatization for many weeks. This fact demonstrates how profound the process of acclimatization can be.
Acute mountain sickness (AMS) can occur to anyone at altitudes above 3,000 m / 10,000 feet. The most common symptoms are breathlessness, coughing, disturbed sleep, headache, inability to concentrate, lassitude, loss of appetite, and nausea.
Leh is situated at an altitude of approx. 3,500 m / 11,500 feet, you are advised to properly acclimatize your body for the first two days by taking complete rest after arrival. Do not exert yourself. Drink enough (at least up to 2 liters) every day. Keep your body hydrated, walk/move slowly, and do not climb higher.
Commonly called altitude sickness, this has the potential to affect all trekkers from 2500m and higher. Your body needs days to adjust to smaller quantities of oxygen in the air - at 5500m/18,044ft the air pressure is approximately half that of sea level, i.e., there is half the amount of oxygen (and nitrogen).
Altitude sickness is preventable. Go up slowly, giving your body enough time to adjust. These are the 'safe' rates for the majority of trekkers: spend 2-3 nights between 2000m/6562ft and 3000m/10,000ft before going higher. From 3000m sleep an average of 300m/1000ft higher each night with a rest day every 900-1000m/3000ft. Ultimately it is up to you to recognize the symptoms, and only ascend if you are relatively symptom-free.
Don't expect to feel perfect at altitudes of more than 3000m. These are the normal altitude symptoms that you should expect BUT NOT worry about. Every trekker will experience some or all of these, no matter how slowly they ascend.
You only need to get one of the symptoms to be getting altitude sickness, not all of them.
Take as far down as possible, even if it is during the night. The patient must be supported by several people or carried by a porter - his/her condition may get worse before getting better. Later the patient must rest and see a doctor. People with severe symptoms may not be able to think for themselves and may say they feel OK. They are not.
This comes on suddenly and severely, usually from both ends - vomiting and diarrhoea. It happens about 4 to 8 hours after eating the contaminated food. Luckily it usually lasts less than 24 hours and recovery is quick, although you may feel weakened.
At altitude, dehydration is a significant issue. Make sure you drink plenty of fluids to stay hydrated, especially in dry, thin air.
Blisters can be a problem during treks. Prevention is key, and prompt action is needed if a blister begins to form.
If you have asthma, higher altitudes can affect you due to cooler and drier air and reduced oxygen levels. Make sure to take appropriate precautions if traveling to higher altitudes.