Sulfamethoxazole Trimethoprim Uses

Sulfamethoxazole trimethoprim is used to treat bacterial infections, including respiratory tract infections (pneumonia, acute exacerbations of a chronic infection), urinary tract infections, and ear infections, and intestinal infections (traveler’s diarrhea). 

This antibiotic is effective against infections caused by the following bacteria: Streptococcus pneumoniae, Escherichia coli, Klebsiella pneumoniae, Enterobacter species, Haemophilus influenzae, Proteus mirabilis, Proteus vulgaris, Morganella morganii, Shigella flexneri, Shigella sonnei, and pneumocystis jiroveci (previously called pneumocystis carinii).

There may be other uses of sulfamethoxazole and trimethoprim—your pharmacist or doctor can give you further drug information.

Sulfamethoxazole Trimethoprim Mechanism of Action

Sulfamethoxazole and trimethoprim block the bacterial folate synthesis pathway and prevent the formation of proteins essential for many bacteria to grow. These antibiotics therefore work by stopping bacterial growth.

Sulfamethoxazole Trimethoprim Doses

Sulfamethoxazole trimethoprim is available in oral tablet form in the following fixed dosage strengths:

• Sulfamethoxazole / trimethoprim: 400 mg / 80 mg
• Sulfamethoxazole / trimethoprim double strength: 800 mg / 160 mg
• Sulfamethoxazole / trimethoprim liquid suspension: 200 mg / 40 mg per 5 mL

The dose of sulfamethoxazole trimethoprim is as follows:

To treat diarrhea (shigellosis) or urinary tract infection in adults:

The recommended adult dose is 2 tablets of sulfamethoxazole and trimethoprim or 1 tablet of sulfamethoxazole and trimethoprim DS (double strength) taken every 12 hours (twice a day). The treatment duration is 10-14 days for a urinary tract infection and 5 days for shigellosis. 

To treat urinary tract infection, shigellosis, or acute otitis media in children:

The recommended dose in children is 40 mg per kilogram of body weight of sulfamethoxazole and 8 mg per kilogram of body weight of trimethoprim per 24 hours, given in two divided doses. The treatment duration is 10 days for urinary tract infection and acute otitis media and 5 days for shigellosis.