There's an increased slight increased risk of a UC flare as the result of a NSAID or a COX-2-inhibitor. Do some of us still take them? Sure sparingly and/or on a limited basis. Of the two, the COX-2-inhibitor would be the safer based on research (if you have a choice).
/www.ncbi.nlm.nih.gov/pmc/articles/PMC4588181/