In my experience the steroid enemas worked immediately to stop bleeding & shrink swollen inflamed tissues, then within a few days, reduced no. of bms, too. They also relieved my "weak-in-the-knees" feeling of exhaustion. By comparison, the mesalamine enemas do not work as fast; one has to be patient with them because they can take 8 weeks or longer to stop a flare. They are not absorbed fully so that one can feel sloshing liquid in lower left side & have mostly liquid bms while taking them nightly. They work topically to reduce inflammation, whereas the steroid enemas work both topically & systemically-- so they do not ordinarily cause major side effects, such as bone loss that can occur with longtime steroid use. / Old Hat (nearly 30 yrs with left-sided UC; currently taking 3 Colazal daily; seem to be back in remission)