Is bactrim (sulfamethoxazole and trimethoprim) antibiotic effective in treating a tooth infection?

No: Amoxicillin and Clindamycin are the antibiotics of choice for dental infections. Bactrim (sulfamethoxazole and trimethoprim) is a poor choice.

Not a normal med: Bactrim (sulfamethoxazole and trimethoprim) can be effective, but it is far down on the list of first choices for a dental infection. There are other antibiotics much more suited to dental bacteria. Your dentist should be able to check your medical history and get you a medication that will work better. Please get treatment as well, antibiotics are short term solutions and cannot reach bacteria inside a tooth.