I had radiation to the lower jaw, neck and chest in two previous cancer dx's and again 4 years ago for Squamous Cell Carcinoma. The first side effect is losing your tasted buds, can't taste. Then Saliva glands go and you have a dry mouth, sores in mouth, dental problems are possible so get your teeth checked.
Some of the effects are reversed with time, taste comes back, saliva glands (sometimes) come back. Overall it's not as bad as chemo for me, but there are some serious side effects.
Hope this helps you.