How to Calculate Sulfamethoxazole 40 mg + Trimethoprim 8 mg / mL Dose

This calculator determines the Sulfamethoxazole and Trimethoprim dose for treating mild to moderate infections, using a concentration of Sulfamethoxazole 40 mg + Trimethoprim 8 mg / mL, based on the patient’s weight (dose based on Trimethoprim component):

Dose in mL and mg (based on Trimethoprim):

Where:

• Weight: Enter the patient’s weight in kilograms (kg) or pounds (lb) and select the unit from the dropdown (automatically converted to kg).
• Concentration: Sulfamethoxazole 40 mg + Trimethoprim 8 mg / mL.

Administer as prescribed for mild to moderate infections. ⚠️ Always consult a healthcare provider.

Using the Sulfamethoxazole 40 mg + Trimethoprim 8 mg / mL Dosage Calculator

Enter the patient’s weight in kilograms or pounds, select the unit, and click "Calculate." The calculator provides the dose in mL and mg (based on Trimethoprim) for pediatric (≥2 months) and adult patients, ensuring the minimum dose (in both mL and mg) is less than or equal to the maximum dose for pediatric patients.

Example: Weight 5 kg:

Pediatric ≥ 2 months:
Min Dose: 2.5 mL (20 mg TMP, 100 mg SMX) PO BID
Max Dose: 3.8 mL (30 mg TMP, 150 mg SMX) PO BID

Adult Dose:
Sulfamethoxazole-800mg + Trimethoprim-160mg PO BID
(20 mL) PO BID

Calculations must be re-checked and should not be used alone...
            

Consult a healthcare provider before administering.

Frequently Asked Questions (FAQ)

1. What is Sulfamethoxazole + Trimethoprim used for?

Sulfamethoxazole + Trimethoprim (TMP/SMX, Co-trimoxazole, Bactrim, Cotrim, Septra, Sulfatrim) is used to treat mild to moderate bacterial infections, such as urinary tract infections, respiratory infections, and certain types of diarrhea.

2. How often is this given?

Pediatric ≥ 2 months: 8 to 12 mg TMP/kg/day PO BID (Max 160 mg TMP/dose). Adults: Sulfamethoxazole-800mg + Trimethoprim-160mg PO BID.

3. Can this be used for infants under 2 months?

Consult a doctor, as Sulfamethoxazole + Trimethoprim is not typically recommended for infants under 2 months without medical supervision.

4. What if weight is in pounds?

Enter the weight in pounds, and the calculator will automatically convert it to kilograms for calculation (1 lb = 0.4536 kg approximately).

5. What’s the maximum dose per administration?

The maximum dose per administration is 160 mg of Trimethoprim (and 800 mg of Sulfamethoxazole) for both pediatric (≥2 months) and adult patients.