Hi! Welcome to the forum! :)
When I was first diagnosed, I was put on Lialda. It didn't really seem to have much impact on me at all (in fact, I felt in some ways that it was getting worse). My doctor thought maybe I wasnt getting ENOUGH of it, so he doubled the dose to 4 pills daily. I got a lot worse on that dosage and was taken off of it.
I have proctitis (located only at the very end of my colon). My doctor told me that since Lialda is released throughout the entire colon, that it was causing the upper part (that is not affected) to create secretions and send that through the rest of my colon and also that by the time the medicine reached the affected part that there wasnt enough left to help.
If your UC is further down in your colon, this might be your problem. OR Lialda just may not be for you! Not all drugs affect people the same way- keep testing one will eventually help! :)