Hi .
Sorry to hear that your teen has UC. It's hard anyway, and to be so young/still in school etc can make it so much harder!
I honestly can't give you a concrete answer because everyone is different - that's why so many different medications are used to treat IBD.. What works for one might not work for another, and the side effects will differ from person to person too!
Mesalamine is often one of the first medications offered, but there are many many more. It's kind of like a pyramid with the treatment options, so you start at the bottom and move up when things don't help improve symptoms or become less effective over time.
Good luck with the Mesalamine.
- Sahara (team member)