I have been prescribed sulfameth/trimethoprim for frequent urinar...

I have been prescribed sulfameth/trimethoprim for frequent urinary tract infections, and even after the fourth time taking it now, I have yet to notice any abnormal side effects. I am also on birth control pills. I know how an allergic reaction is for me (I am allergic to pennicilin and broke out in a HORIBBLE rash all over my face last year), and I haven't experienced anything even approaching an adverse reaction, plus my infection clears up within the first couple of days.