What nawlinsgate said . . .
The side effect ratio for 6mp is probably less than 10%, maybe as low as 5%. The response ratio is very high, and if it works in your case it can be the long term maintenance med that will keep you perking along without all the hassles of IVs and needles from drugs like Remicade and Humirs. I would wager that more people on this forum are on 6mp for their Crohns than any other drug.