I know a few people with social anxiety and I personally suffer from anxiety myself, just a different form of it.
Recommending a good cousellor is a start. They can give him exercises to do to help him face his fears. It all begins in the mind and can be rather crippling. What seems to happen is when certain thoughts are repeated, it will begin to effect the person physically as well as their life responses.
You can be a good friend to him and walk with him as he goes through therapy. He is going to need you. Remember, his fears are REAL to him. It's quite humbling to have to see a mental health specialist but he really should see someone.
Life is meant to be lived!!!
A word of caution, try to stay away from meds if possible. For me personally, I figured I would have to renew my mind to be set free from myself and my thoughts. The meds can just be a crutch (although, there are many who NEED the meds because of brain chemistry imbalances) I'm just saying to try it without the meds first.
Blessings to you on your journey.