I hate to tell you this - and I feel like I probably sound like a broken record on this forum - but Pentasa is not going to do squat for moderate to severe Crohn's disease. By putting you on prednisone and then recommending Pentasa, your doctor has demonstrated that he is a good 20 years behind the times in treating Crohn's disease. Recent studies the last several years have shown Pentasa is no better than placebo. Prednisone is effective but causes as many problems as it solves, and is only to be used in the short term as a last resort.
If at all possible, find another GI who specializes in treating IBD (Crohn's and UC). You should be on a more effective maintenance med. If your Crohn's is indeed moderate to severe, you should probably jump right to the biologics such as Remicade or Humira.
I throw my hat into the "agreeing with beave" camp.
I was diagnosed in 2000, so the biologics were barely available in America, let alone the UK. Going purely by symptoms, my case was a mild one to begin with. My doctors threw various mesalazines (which is what Pentasa, Asacol, etc. is) at me for the next 5 years, even though I could not tolerate them and got extreme reactions. Obviously didn't make myself clear enough 'cos they kept on trying the mesalazines with me.
By the time my hospital got around to prescribing a stronger class of med (azathioprine), my disease and symptoms had already taken a sharp turn for the worse. This was in 2005, I think. I perhaps didn't give it as long as I could've done (or am I thinking of the 2nd time I was on azathioprine? Aargh :-/), but it didn't help. Cue five years of steroids and immunesuppressants, and being messed about
with. In 2011 I changed hospital and my new GI got me onto Remicade straight away. But by that time it was too late, my colon was beyond saving. Ended up needing a colectomy.
It was never going to happen, but if I could have got onto Remicade in 2000, I might still have my colon. I'd rather take nothing than Pentasa, which is precisely what I'm doing right now. Been in remission for 2 years and counting. If the disease comes back, I'm gonna try to get onto a biologic straight away - if I can't do that, then 6MP or azathioprine. What I won't do is waste even a week of my time on a mesalazine/mesalamine (same thing, different spelling).
I sincerely hope we haven't scared you away, goldengirllover. Welcome to HW.... :-/