Some people do have adverse reactions to mesalamine - or the delivery system, which is why there are different meds (Asacol, Colazal, Pentasa, Lialda).
This would be a good thing to discuss wiht your doctor.
Pan-colitis and GERD diagnosed May 2003
Osteopenia diagnosed Feb 2006
Status: Flaring :(
30mg pred, Asacol 12 per day, Azathioprine 100mg, Aciphex, Forvia, and Pro-Bio