Praxis Medical Insights

Est. 2024 • Clinical Guidelines Distilled

Made possible by volunteer editors from the University of Calgary & University of Alberta

Last Updated: 9/22/2025

Trimethoprim-Sulfamethoxazole for Acute Uncomplicated Cystitis

  • For acute uncomplicated cystitis in women, the recommended regimen is trimethoprim-sulfamethoxazole (TMP-SMX) 160/800 mg twice daily for 3 days, but should only be used when local resistance rates are less than 20%. 1, 2

  • TMP-SMX 160/800 mg (one double-strength tablet) orally twice daily for 3 days is the optimal regimen for uncomplicated cystitis. 1, 2, 4

  • The 3-day regimen achieves clinical cure rates of 90-100% when the uropathogen is susceptible. 2, 4

  • Early bacteriologic cure rates are 91% with the 3-day regimen. 4

  • TMP-SMX 160/800 mg twice daily for 7 days may be considered in selected cases. 1, 2

  • The 7-day regimen showed clinical cure rates of 86-95% in comparative studies. 2

Resistance Considerations

  • When the uropathogen is susceptible to TMP-SMX, the cure rate is 84%. 4

  • When the uropathogen is resistant to TMP-SMX, the cure rate is only 41%. 4

  • TMP-SMX should only be used empirically when local resistance rates are <20%. 1

Contraindications

  • Beta-lactams (amoxicillin, ampicillin) should not be used for empirical treatment due to high resistance and inferior efficacy. 1

REFERENCES

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