Went to dr thru. for a uti and they gave me septra (sulfamethoxazole and trimethoprim).. i take it every 12 hours.. and it stil hurts when i pee.. how long should this med. take to work?

Depends: Septra (sulfamethoxazole and trimethoprim) is a pretty good abx for uti, but sometimes there are causes to which septra (sulfamethoxazole and trimethoprim) does not work due to resistance. Other times the bladder wall can be irritated from the infection causing pain. But if you continue to have burning sensation with septra (sulfamethoxazole and trimethoprim), i would advise further f/u care and perhaps a urine culture to determine whether or not there is resistance.