Hi Karen. My husband's doctors did not advise the Ethyol, but we wanted to try it anyway, as initially, I was very scared and worried about the "quality of life" effects my husband would face from radiation. He tried it, lasted only one day, as it made him extremely ill. He could not face another day of it, so we decided it wouldn't be worth it. After all is said and done, I am glad he didn't try to keep taking it and put himself through even more misery, because although he has a very dry mouth, it is very manageable, he doesn't have to constantly be drinking something. This is even with him having had conventional radiation, which is supposed to be worse than IMRT as far as affecting saliva glands. I don't want to talk you out of having your dad consider Ethyol, because there are some who can tolerate it, but as Nelie points out, it isn't totally effective even if you can tolerate it.
Best of luck to your dad.
Michele