Alcohol abuse...what will happen?

a family friend is a 60-odd yr old male, had already a serious health condition and is now on a tail of drugs to keep him immunosupressed and control blood pressure etc. Since sunday evening he has consumed almost 2 bottles of gin the label says 28 units each apparently! and he doesnt bat an eyelid at this. His wife says he has mood swings- can i ume this is part of the reason? and what might happen next? How can you tell a stubborn old man that he has to change his ways?!- obviously he doesnt mention it to medical staff when he's having check ups! any help/advice i can p on would be fab thanks xx