Pentasa and maintenence

last year i had a parasite . did not know this for 3 months. my diarehia turned into ulcerative colitis. this was all confirmed by a colonascopy. had to take flagel for the parasite and medication for the colitis. also took prednisone. my dr. wants to put me on pentasa to take as a maintenence pill. what are the side effects to this pill. i am doing very well now and i really don't feel confortable taking 1500mg. a day all the time. what do you think????? and what are the side effects????????? thank you