It's not pleasant but it is generally considered to be safe in normal doses. To give you an idea of how ubiquitous its use is, it is used on 3 day old kittens and they're always fine. Then again, each patient is different and know one knows her better than her family, and if they feel it poses a risk, then that's fair enough.

Quality of life is also important, and her experience sounds unpleasant, so your concern is justified regardless.