At-a-glance
• In non-pregnant women with typical lower UTI symptoms, treat empirically unless severe/atypical features.
• Review at 48 hours if not improving; reconsider diagnosis and send culture where indicated.
• In pregnancy, treat for 7 days and culture is usually appropriate.
Assess and rule out “not lower UTI”
- Suggestive of pyelonephritis / complicated UTI: fever, flank pain, rigors, systemic upset, vomiting, pregnancy with systemic features, known urological abnormality, immunosuppression, catheter-associated infection → follow pyelonephritis/complicated UTI pathways.
- Consider alternatives: STI/urethritis, vaginitis, interstitial cystitis, nephrolithiasis, atrophic vaginitis, pelvic pathology.
- Urine culture is particularly helpful: pregnancy, recurrent UTI, treatment failure, atypical symptoms, suspected pyelonephritis, recent resistant organisms/antibiotics, or significant comorbidity.
Non-pregnant women (NICE NG109)
First choices (3 days):
- Nitrofurantoin (if eGFR ≥45 mL/min): 100 mg modified-release twice daily (or 50 mg four times daily if MR unavailable) for 3 days.
- Trimethoprim (if low risk of resistance): 200 mg twice daily for 3 days.
Second choices (if no improvement after at least 48 hours on first choice, or first choice not suitable):
- Nitrofurantoin (if not used first-line and eGFR criteria met): 100 mg MR twice daily (or 50 mg QDS) for 3 days.
- Pivmecillinam: 400 mg initial dose, then 200 mg three times daily for a total of 3 days.
- Fosfomycin: 3 g single-dose sachet.
Notes: Nitrofurantoin may be used with caution at eGFR 30–44 only in specific circumstances (balance risks/benefits). Check prior cultures/antibiotic exposure and local resistance patterns.
Pregnant women aged ≥12 years (NICE NG109)
First choice (7 days):
- Nitrofurantoin (if eGFR ≥45): 100 mg modified-release twice daily (or 50 mg QDS) for 7 days. Avoid at term (risk of neonatal haemolysis).
Second choices (7 days) (if no improvement after at least 48 hours on first choice, or not suitable):
- Amoxicillin 500 mg three times daily for 7 days (only if culture results are available and susceptible).
- Cefalexin 500 mg twice daily for 7 days.
- Otherwise: consult local microbiology and base on culture/susceptibility.
Safety net and review
- Reassess urgently if: fever, flank pain, rigors, worsening systemic symptoms, vomiting, or pregnancy with systemic features.
- No improvement at 48 hours: confirm adherence, send urine culture (if not already), consider alternative diagnosis, and switch per NICE second-choice options or culture results.
Frequently asked questions
When is trimethoprim “low risk of resistance”?
NICE notes lower resistance risk is more likely if trimethoprim has not been used in the past 3 months, prior culture suggests susceptibility, and in younger people/areas with low resistance.
Can I use nitrofurantoin when eGFR is 30–44?
NICE notes cautious use may be considered in specific circumstances for uncomplicated lower UTI due to suspected/proven multidrug-resistant bacteria when benefits outweigh risks. Use judgement and follow local policy.
Should I always culture in pregnancy?
Culture is generally appropriate in pregnancy given higher stakes and to guide therapy, especially if symptoms persist or recur.
Transparency
This page is an educational, clinician-written summary of publicly available NICE guidance intended for trained healthcare professionals. It uses original wording (not copied text) and should be used alongside the full NICE source, local pathways, and clinical judgement. Doses provided are for general reference; always check the BNF/SPC.