The right Bactrim dosage depends on factors such as the infection being treated, your age, and your kidney function. Below, we’ll cover typical Bactrim dosages for adults and children, along with tips for taking it safely. Medscape - Indication-specific dosing for Bactrim, Bactrim DS, Septra, Septra DS, Cotrim, cotrimoxazole, Sulfatrim (trimethoprim, sulfamethoxazole), frequency-based adverse effects. Bactrim is used to treat certain types of infections. Find out what the recommended dosages are, how to take the drug, and more. For UTI, the typical Bactrim dosage for adults is either 1 or 2 tablets, depending on the strength. You will take your dose for 10-14 days. The active ingredients in Bactrim are sulfamethoxazole. 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. How should I use Bactrim? Take Bactrim exactly as prescribed by your doctor. Follow all directions on your prescription label and read all medication guides or instruction sheets. Drink plenty of fluids to prevent kidney stones. Antibiotic medicines can cause diarrhea. Detailed dosage guidelines and administration information for Bactrim (sulfamethoxazole and trimethoprim). Includes dose adjustments, warnings and precautions. Learn how to take Bactrim safely, including when to take doses, what to avoid, and which side effects warrant a call to your doctor. Typical adult doses range from 800 mg sulfamethoxazole combined with 160 mg trimethoprim twice daily. Children’s doses are carefully calculated based on weight and condition severity. Missing doses or overdosing can lead to treatment failure or serious side effects. Adults generally take one double-strength tablet twice daily for most infections. The duration depends on the infection type, often 3 to 14 days. For severe infections, dosing frequency and amount may increase under medical supervision.