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Sulfamethoxazole/Trimethoprim Dosage
The recommended sulfamethoxazole/trimethoprim dosage for most uses is 800/160 mg every 12 hours. The length of treatment, which ranges from 5 to 14 days, will vary depending on the type of infection being treated. This 800/160 mg dose can be taken as one double-strength tablet, two regular-strength tablets, or 4 teaspoonfuls of the oral suspension (liquid).
The dose of sulfamethoxazole/trimethoprim (Bactrim®, Bactrim® DS, Septra®, Septra® DS, Sulfatrim®) that your healthcare provider recommends will vary, depending on a number of factors, including:
- The type of infection and bacteria
- Your height and weight (for some uses)
- Other medical conditions you may have
- Other medications you may currently be taking.
As is always the case, do not adjust your dosage unless your healthcare provider specifically instructs you to do so.
The recommended sulfamethoxazole/trimethoprim dosing for adults with normal kidney function is as follows:
- Pneumocystis carinii pneumonia treatment -- dosage based on weight, taken every 6 hours for 14 to 21 days
- Pneumocystis carinii pneumonia prevention -- sulfamethoxazole/trimethoprim 800/160 mg once daily
- Urinary tract infection (UTI) treatment -- sulfamethoxazole/trimethoprim 800/160 mg every 12 hours for 10 to 14 days
- Shigellosis or traveler's diarrhea treatment -- sulfamethoxazole/trimethoprim 800/160 mg every 12 hours for 5 days
- Acute worsening of chronic bronchitis treatment -- sulfamethoxazole/trimethoprim 800/160 every 12 hours for 14 days.
The dose of sulfamethoxazole/trimethoprim 800/160 mg can be taken as one DS ("double-strength") tablet, two regular-strength tablets, or 4 teaspoonfuls (20 mL) of the oral suspension (liquid).
Lower sulfamethoxazole/trimethoprim dosages may be recommended for people with kidney disease.
Written by/reviewed by: Kristi Monson, PharmD; Arthur Schoenstadt, MD
Last reviewed by: Kristi Monson, PharmD