Acute Mountain Sickness(AMS) is common at high altitudes, and depends on the elevation, the rate of ascent and individual susceptibility. Most visitors to Tibet will suffer from at least some symptoms that will generally disappear through acclimatization in several hours to several days.

Symptoms tend to be worse at night and include headache, dizziness, lethargy, loss of appetite, nausea, breathlessness and irritability. Difficulty sleeping is another common symptom, and many travelers have trouble sleeping for the first few days after arriving in Lhasa.

To prevent acute mountain sickness:
Drink extra fluids. The mountain air is dry and cold and moisture is lost as you breathe. Evaporation of sweat may occur unnoticed and result in dehydration.
Eat light, high-carbohydrate meals for more energy.
Avoid alcohol as it may increase the risk of dehydration, and don't smoke.
Avoid sedatives.
Don't push yourself when climbing up to passes, rather take plenty of breaks.
Avoid catching cold before you entering Tibet.

Tibet Tour Expert says:
For all of the groups , the authorized doctor from Tibet Tour Expert will come to guest's room to give a regular check. For the people who are affected severely with headache and sleepless, they could get injection in the room or take some Tibetan medicine as per doctor's advices. Many of our clients have been treated and approved for its efficiency.

Who can't go?
Tibet Tour Expert may suggest whose clients who suffered from high blood pressure and severe heart disease not travel to Tibet.