Hard to say. I know fatigue is something that plagues a number of us with UC. And the same goes for headaches. Those can happen to those of us who are on medications and also who are not on any medications. I'd bet their more side effects of UC than anything else.
You could always ask your gasteroenteroligist to have you try a different formulation of mesalamine, as an experiment to see if it helps. You could try pentasa, as an example.
Moderator Ulcerative Colitis
John, 39, UC Proctosigmoiditis
Rx: Remicade @5mgs/kg/6wks; daily 75mgs 6MP, 4.8g generic-Lialda, and rowasa
iPoop, uPoop, weAllPoop too urgently and frequently for UC.