Medical questions & health advice by board certified doctors

"Should I continue with my antibiotics?"

ZocdocAnswersShould I continue with my antibiotics?


Last year, I was prescribed Bactrim for a UTI. I stupidly did not finish the full course. The symptoms of a UTI would come and go throughout the year. Recently, it became a full blown UTI that warranted a visit to the doctor. Initially, I was prescribed Macrobid, but the culture result came and they wanted to switch me to Bactrim. My understanding is that if you don't finish an antibiotic, you run the risk of having bacteria which are resistant to that particular antibiotic. Should I continue with the Bactrim even though I didn't finish the full course a year ago?


This is an excellent question and it sounds like you have been thinking through things very carefully. The best thing to do is to discuss this with your physician. You are right that whenever prescribed antibiotics it is always a good idea to finish the complete course to make sure that you don't develop recurrent symptoms from an incompletely treated infection. With UTIs sometimes patients will be prescribed an empiric antibiotic without actually testing the bacteria to see what they are sensitive too--this works most of the time but of course is not 100%. Either bactrim or macrobid are very good first choices for empiric therapy in most choices. However, once a culture is done, that allows physicians to determine exactly what the bacteria are sensitive too...and in your case it sounds like they are resistant to macrobid and sensitive to bactrim. This makes bactrim an excellent choice. In order to develop antibiotic resistance, it typically takes exposure to a specific antibiotic multiple times, and an incomplete course of bactrim a year ago is not likely to have led to this. In addition, culture data always trumps empiric dosing. If you have any questions you can always discuss this with your physician.

Zocdoc Answers is for general informational purposes only and is not a substitute for professional medical advice. If you think you may have a medical emergency, call your doctor (in the United States) 911 immediately. Always seek the advice of your doctor before starting or changing treatment. Medical professionals who provide responses to health-related questions are intended third party beneficiaries with certain rights under Zocdoc’s Terms of Service.