Find patient medical information for Sulfamethoxazole Oral on WebMD including its uses, side effects and safety, interactions, pictures, warnings and user ratings. Introduced in 1968, trimethoprim–sulfamethoxazole remains a popular antibiotic because of its low cost, effectiveness and familiarity among clinicians. Sulfamethoxazole can enhance the blood-thinning effects of warfarin , possibly leading to bleeding. Sulfonamides such as sulfamethoxazole can increase the metabolism (break-down and elimination) of cyclosporine (causing loss of effectiveness of cyclosporine), and can add to the kidney damage caused by cyclosporine. Potentiation of warfarin by trimethoprim-sulfamethoxazole (TMP-SMX) has been reported occasionally but not in the urologic literature. Three cases are presented in which significant bleeding developed when TMP-SMX was added for the patient already on warfarin anticoagulants. Trimethoprim & Warfarin Hi there, I react very badly to infection and virus and indeed to drugs, I think once you have gone the course with the antibiotic you will feel better, but probably the infection plus the. sulfamethoxazole-trimethoprim oral brand names and other generic formulations include: Bactrim DS Oral, Bactrim Oral, Bethaprim DS Oral, Cheragan With Tmp Oral, Cofatrim Forte Oral, Comoxol Oral, Cotrim Double-Strength Oral, Cotrim Oral, Dynasep DS Oral, Dynasep SS Oral, Kidtrim DS Oral, Pediatrim Oral, Septra DS Oral, Septra Oral, SMZ-TMP DS. Sulfamethoxazole and trimethoprim are both antibiotics that treat different types of infection caused by bacteria. Sulfamethoxazole and trimethoprim is used a combination antibiotic used to treat ear infections, urinary tract infections, bronchitis, traveler's diarrhea, shigellosis, and Pneumocystis jiroveci pneumonia. TMP/SMX (Bactrim; Septra) is a frequently prescribed antibiotic but is also known to have clinically relevant drug interactions with warfarin. Eleven normal humans were studied to evaluate the reported interaction of racemic sodium warfarin and trimethoprim-sulfamethoxazole prospectively. 1. Ann Intern Med. 1979 Jul;91(1):34-6. Racemic warfarin and trimethoprim-sulfamethoxazole interaction in humans. O'Reilly RA, Motley CH. Eleven normal humans were studied to evaluate the reported interaction of racemic sodium warfarin and trimethoprim-sulfamethoxazole prospectively.