Technically, a true remission excludes use of steroids like prednisone.
Are you on only prednisone at this time?
You can try generic mesalamine oral at 4,800mgs a day, and a nightly 4,000mg mesalamine enema and see if you can sustain on those without prednisone. It's possible you might be able to. However it is equally possible that you cannot and will flare up again. The only way is to know for certain is to try those medications and slowly reduce the prednisone to findout if your flare returns or not.
You could go on both the oral mesalamine and 6mp, as combination therapy seems to be the best approach to treating UC. I've been on 6mp since 2012 and have yet to have a side effect from 6mp. Side effects are rare. The Crohn's and Colitis Foundation of America has a good risks versus benefits read/watch on medications like 6mp. I found it helpful when initially deciding to go on 6mp:
Webcast:
programs.rmei.com/CCFA139VL/presentation/player.htmlTranscript
: http://www.ccfa.org/assets/pdfs/risk-and-benefits-transcript
.pdf
Just know that 6mp takes a full 3-months to work, so delaying it can potentionally extend your time on prednisone out for additional months. You'd concurrently be on pred and 6mp until the 6mp has an affect. Afterwards, you would taper down the pred.