did he have as asthma in Nepal? if not then he is surely allergic to something that's causing asthma...have him check for food allergy and series of other allergies..believe it or not something simple such as wheat can trigger severe asthma...

there is no cure for asthma..one can only manage it....

he can also be allergic to mold, dust, cats, dogs etc...

I know a lot of ppl from Nepal who has moved to the US develop these severe allergic reactions that turns into asthma.. he should definitely have inhalers around the clock...i hope he has health insurance..

on natural remedies...ginger sometimes does the job in managing asthma.. it really sucks to be asthmatic.  for me for some reason when i am back in KTM i have no allergic reactions..

Hope your friend will find a way to manage it.