One of the extra fun symptoms you may get with a Crohn's flare is mouth sores. I get both cold sores and canker sores.
Today I read about a home remedy for canker sores that sounds interesting. It's a parents' favorite, sometimes called "magic mouthwash."
Mix equal parts children's benadryl liquid and mylanta antacid. Swab on cold sores with a q-tip or use it to gargle. Some doctors will have a pharmacy compound a version of this along with RX viscous lidocaine.
Of course my own home remedy is to gargle with hot salt water. Cures them up very well. And for cold sores RX zovirax is the stuff. For my 3 year old what I did was put salt on a wet q-tip and stick it on the mouth sore since he didn't know how to gargle yet.
I also have had good results with Colgate Peroxyl, a peroxide mouth rinse. It seems to kill the canker sores and doesn't sting, but it does get foamy.