The Treatment to the High Altitude Sickness

Treat mild symptoms by resting at the same altitude until recovery, usually
a day or two. Take paracetamol or acetaminophen for headaches. If
symptoms persist or become worse, however, immediate descent is
necessary. Even 500m can help.

The most effective treatment for severe AMS is to get down to a lower
altitude as quickly as possible. In less severe cases the victim will be able
to stagger down with some support; in other cases they may need to be
carried down. Whatever the case, any delay could be fatal.

AMS victims may need to be flown out of Tibet as quickly as possible, so
make sure you have adequate travel insurance.
The drug acetazolamide (Diamox) is recommended for the prevention of
AMS - take 125mg twice a day as a preventive dose. Be aware that even
when you are on Diamox, you should not ignore any symptoms of AMS.

However, the use Diamox is controversial. It can reduce the symptoms,
but may also mask warning signs; severe and fatal AMS has occ urred in
people taking this drug. Travellers should discuss the use of Diamox with a
travel health expert. Diamox should be avoided in those with a sulphur
allergy, but you can discuss taking a trial of the medication at home if
necessary.

Drug treatments should never be used to avoid descent or to enable
further ascent (although they can help get people well enough to
descend)

Info comes from Travel to Tibet