It can take a few days to a couple weeks to notice a change. Is that all you're taking? It may not be strong enough. Prednisone is much more aggressive and usually works within that amount of time. I've taken Entocort (not the enema form) and it did seem to help but I never took it alone. For flares that are so bad one usually takes steroids (ex: Prednisone/Entocort) to control inflammation quickly and drugs to help maintain the reduced inflammation (Asacol, Pentasa, Salofalk, Lialda and Apriso) and often times drugs that suppress the immune system (6MP, Imuran, and Humira) to try to control the disease itself (there are a lot of other meds including Remicade but I can't think of which category they all fall under at the moment).