Traveling in Tibet involves high altitude and can be strenuous. Clients with heart and lung problems or blood diseases should consult their doctor before booking the trip. Most people will experience some of the minor symptoms and discomfort of altitude sickness, until their body adjust to the elevation. This can take from a few hours to couple of days, depending on the individual. Very rare cases of acute altitude sickness have been reported. Simple headache, fever, loss of appetite and stomach disorders can happen before the acclimatization. Advised, drink approximate 3 liters of water per day, do not strain yourself, move slowly, breathe deeply and take regular rests please do not smoke & do not drink alcohol.