Sulfamethoxazole / trimethoprim
"I have reoccuring UTI's and have taken several different antibiotics for them.  I was recently prescribed Bactrim DS.  After taking the second pill, the aching, pain and soreness was almost gone.  It works better for me than Cipro, but you should always have a urine culture to be sure which antibiotic is best for you.  Fortunately, I haven't had any terrible side effects.  The only side effect is feeling a bit fatiqued a few hours after taking Bactrim."