My daughter has Ulcerative Colitis (very similar to Crohn's) and was first diagnosed at 6 years of age. She's 11 now. She's on Colazal and Mercaptopurine. There's a wonderful support board/community that I go to for parents of children with IBD. The parents there have experience with all of the meds used to treat IBD. I'll try to post the link, but I'm bad at these things.
Here goes: http://ibdsupport.dragonpack.com/parents/
Here goes: http://ibdsupport.dragonpack.com/parents/