Can you take doxycycline mono and sulfamethoxazole-trimethoprim at the same time?

Bactrim (sulfamethoxazole and trimethoprim) and Doxy: Hello, for complicated infections, doctors often times use more than one antibiotic. Make sure your doctor knows you are taking 2 antibiotics. If one doctor is treating a urinary infection and another is treating a bronchitis with two antibiotics, you may be over medicated. Each patient that walks into our office poses a unique challenge. Make sure your family doctor is aware of your medication.