Levels of BACTRIM in breast milk are approximately 2 to 5% of the recommended daily dose for pediatric patients over two months of age. There is no information regarding the effect of BACTRIM. The safety of trimethoprim-sulfamethoxazole (TMP-SMX) in children has not been systematically evaluated. Use in children less than 2 months of age generally is not recommended. Detailed Sulfamethoxazole / Trimethoprim dosage information for adults and children. Includes dosages for Urinary Tract Infection, Bronchitis, Cystitis and more; plus renal, liver and dialysis adjustments. For uncomplicated UTIs in adults, the standard Bactrim dose is one double-strength (DS) tablet containing 800 mg sulfamethoxazole and 160 mg trimethoprim, taken twice daily for 3 to 7 days. Medscape - Indication-specific dosing for Bactrim, Bactrim DS, Septra, Septra DS, Cotrim, cotrimoxazole, Sulfatrim (trimethoprim, sulfamethoxazole), frequency-based adverse effects. The usual dose is 750 mg of sulfamethoxazole and 150 mg of trimethoprim per square meter (m [2]) of body surface each day. This is given in equally divided doses two times a day for 3 days a week on consecutive days (eg, Monday, Tuesday, Wednesday). Bactrim is a prescription drug used for certain types of bacterial infections. Learn about its dosage, including its form, strengths, how it's taken, and more. Bactrim is used to treat certain types of infections. Find out what the recommended dosages are, how to take the drug, and more. Detailed dosage guidelines and administration information for Bactrim (sulfamethoxazole and trimethoprim). Includes dose adjustments, warnings and precautions. Calculate trimethoprim-sulfamethoxazole dose for adults and children by weight and indication. Shows TMP and SMX components, formulation amounts for suspension, SS/DS tablets, and IV with dilution guidance.