oregano oil is some powerful stuff, yes, although, it is something to take slow but not fear :D.
Begin with 1 drop in your choice of drink and work your way up to what is comfortable for you. Now that it is cold/flu season, it can help keep it from you.
As for the bath, a couple drops is good to start. I have a friend who can put in almost (if not exact) 10 drops into her bath. It no longer affects her on the 'ouch' side. She did work her way up, though.