Cathy,
From what I know everyone does experience certain side effects from head and neck radiation, although the degree differs from person to person. It seems that everyone has mucousitis and swallowing difficulties, which eventually clear up for most people and just about all of us suffer from reduced salivation, which to some degree is permanent.
This is the price that we pay for staying alive. You do what you have to do

Best of luck with your mom,
Danny G.