I have forgotten to take my pentasa (mesalamine) tablets for crohn's , should i be worried?

Not worried,: But let your doctor know how often you have forgotten to take it. Without that information, he won't be able to assess the effectiveness of the medication.

Start up again: It sounds as if you'd forgotten for a short time. Just start taking your medication again as instructed and follow up with your doctor as planned. Of course, see your doctor sooner for any new problem.

Retake: Just restart them. Typically if you miss one or two doses, nothing bad should happen in such a short period of time. However if you are ROUTINELY missing doses, you are more likely to have a flare up. If you really don't think you can take your medications without forgetting, discuss other medical options with your GI doctor