Travelling in Himayan Region can be risky if the traveller doesn't take little actions to protect himself and if he doesn't know how to listen to the signals his body gives him. When someone goes in high altitude, it's normal that his body needs to acclimatize. Normally he feels strange, he feels tired, he feels his breathe becomes shortest than before, and needs urinate frequently. It's is normal. The things he has to do to feel better are: be calm, walk slower, a modest increase of fluids , not to ascend more than 400 meters per day in sleeping elevation. Slowly he will see that the symptoms will disappear. If not the only thing he has to do is DESCEND.

Nobody can advise a traveller to take that medicine or another. Only a Doctor can do it, your doctor can tell you which kind of pill or medicine you have to take. This is very important. pills are not Candy or Sweet, or Fruit Drop.

Here one article of Thomas E. Dietz of "International Society for Mountain Medicine" that can help the travellers to know better what is the High Altitude Sickness:

http://ismm.org/index.php/normal-accl...

Some other articles : http://wwwnc.cdc.gov/travel/yellowboo... ( CDC altitude advisory ) 

http://www.wemjournal.org/article/S10... ( evidence based guidelines from Wilderness Medical Society ) 

http://library.thinkquest.org/10131/n...

Added by Rhythm D: 

Some very good information can be found at Wikipedia page too. The page has detailed information about the Sickness, Sign and Symptoms, Prevention and Treatment. Please read it here:  http://en.wikipedia.org/wiki/Altitude...