I am 35 years old and for the past 3 days I was suffering from a very serious urinary tract infection. I was having burning sensation in my urethra. My problem also gave me one sleepless night. I went to the doctor today only who prescribed me septra. I have searched a lot and found that it contains a combination of sulfamethoxazole and trimethoprim. I would like to know from people about the possible septra side effects!! Thanks!