I became gluten intolerant about a year ago. Trimethoprim has always worked well to relieve my symptoms of UTI, however, this time my stomach became sorer and sorer each day I took my daily dose of Trimethoprim. I have noticed in the information about trimethoprim that it contains starch, so I assume that it must also contain gluten. If this is the case, what antibiotic should I use next time I have a UTI? The offending bacteria is either E.coli or 'no growth detected'. Bactrim does not work for me.