antimicrobial prophylaxis in non pregnant women with recurrent urinary tract infection (UTI)

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Recurrent UTI >= 3 per year

Recurrent urinary tract infections (UTIs) in women are common, result in considerable morbidity and expense, and can be a management problem for clinicians. Behavioural changes can be useful antimicrobial-sparing measures in the prevention of ecurren UTIs, but antimicrobial prophylaxis may be necessary in those who continue to have recurrences. Continuous prophylaxis, post-coital prophylaxis and intermittent self-treatment with antimicrobials have all been demonstrated to be effective in the prevention of recurrent uncomplicated UTIs. The decision as to which approach to use depends upon the frequency and pattern of recurrences and willingness of the patient to commit to a specific regimen.

Before any prophylaxis regime is initiated then eradication of a previous UTI should be assured by a negative urine culture one to two weeks after treatment (1,2,3)

Continuous prophylaxis:

Continuous prophylaxis has been demonstrated in numerous studies in different populations to decrease recurrences by 95% when compared with placebo or with patients' prior experience (from 2.0-3.0 episodes per patient-year to 0.1-0.2 per patient-year)

Initial trial of 6-month prophylaxis antibiotics

Most authorities advocate a 6-month trial of prophylaxis, with the dose administered at night, after which the regimen is discontinued and the patient observed for further infection. The rationale for the 6-month prophylaxis period is empiric, based on observations that UTIs seem to cluster in some women.

  • before any long term prophylaxis regimen is initiated, eradication of a previous uropathogen should be confirmed by a negative urine culture 1-2 weeks after treatment
  • trimethoprim 100 mg once daily OR Nitrofurantoin 50-100 mg once daily may be used (4,5)
  • either should be tried for 6 months then stopped
    • N.B. Nitrofurantoin is contraindicated if eGFR <60ml/min (due to the drug being ineffective in poor renal function as it does not concentrate in sufficient quantities in the urine)
    • patients prescribed long term nitrofurantoin should be monitored closely for signs of chronic pulmonary reactions and hepatitis for full details of contraindications and side effects see the manufacturer's Summary of Product Characteristics (SPC)
  • 60% of women will develop symptoms within 3-4 months of discontinuation and so will require long term prophylaxis (4,5)
    • it appears that most women revert back to the earlier pattern of recurrent infections once prophylaxis is stopped unless other factors, such as sexual activity or diaphragm-spermicide use, are modified. Some authorities advocate a longer period of prophylaxis -2 or more years - in women who continue to have symptomatic infections

NICE state choice of antibiotic: people aged 16 years and over (excluding pregnant women) (5)

First choice antibiotic 1,2

  • trimethoprim4
    • 200 mg single dose when exposed to a trigger, or 100 mg at night
  • OR

  • nitrofurantoin - if eGFR >=45 ml/minute5
    • 100 mg single dose when exposed to a trigger, or 50 to 100 mg at night

Second choice antibiotic

  • amoxicillin 6 500 mg single dose when exposed to a trigger, or 250 mg at night
  • cefalexin 500 mg single dose when exposed to a trigger, or 125 mg at night

  • 1 See BNF for appropriate use and dosing in specific populations, for example, hepatic impairment, renal impairment, pregnancy and breast-feeding.
  • 2 Choose antibiotics according to recent culture and susceptibility results where possible, with rotational use based on local policies. Select a different antibiotic for prophylaxis if treating an acute UTI.
  • 3 Doses given are by mouth using immediate-release medicines, unless otherwise stated.
  • 4 Teratogenic risk in first trimester of pregnancy (folate antagonist; BNF, August 2018). Manufacturers advise contraindicated in pregnancy (trimethoprim summary of product characteristics).
  • 5 Avoid at term in pregnancy; may produce neonatal haemolysis (BNF, August 2018)
  • 6 Amoxicillin is not licensed for preventing UTIs, so use for this indication would be off label. The prescriber should follow relevant professional guidance, taking full responsibility for the decision. Informed consent should be obtained and documented

  • refer or seek specialist advice if underlying cause unknown or cancer suspected

Other agents used for UTI prophylaxis include:

  • ciprofloxacin 125 mg nocte
  • norfloxacin 200 mg nocte
  • ofloxacin 100 mg nocte

*Consult local laboratory guidance for local antibiotic policies


  • "any woman who has recurrent, symptomatic and unexplained urinary infections should be referred for investigation using radiological imaging such as ultrasonography, to exclude anatomical abnormalities." (3)


Last edited 11/2018 and last reviewed 04/2019