Trimethoprim/ Sulfamethoxazole is available under the following different brand names: Bactrim , Bactrim DS , Septra, Septra DS , Cotrim, Cotrimoxazole, Sulfatrim. Bactrim DS Tablet is a combination of Trimethoprim and Sulfamethoxazole that treats various bacterial infections in children and adults. It can cause side effects like nausea, diarrhoea, rash, etc. and is not recommended for pregnancy, breastfeeding, or severe liver/kidney problems. Dosage for Bactrim Bactrim is available in tablets in two strengths; 400 mg sulfamethoxazole and 80 mg trimethoprim and the " DS " form which means double strength, 800 mg sulfamethoxazole and 160 mg trimethoprim. Patients should follow their doctor's instructions and take all of the Bactrim prescribed. Bactrim is a combination of two medicines: Sulfamethoxazole and Trimethoprim. It treats infections of urinary tract, ear, intestines, pneumonia and more. Learn about its uses, side effects, precautions and reviews.