I was there for 4 days last December but did not have any problem. My wife had headaches at night for a few dayS, she took some aspirins. I bought an oxygen bottle at the airport but did not have to use it. You can get something from your doctor, I forgot the name of the pills. Your body will adjust to the altitude in Lhasa within a few days, so i would not worry. I have asthma and nothing happened to me.