Synopsis
Diagnose lower urinary tract infection without overcalling colonisation, identify upper-tract or septic disease and prescribe short, safe, susceptibility-aware treatment for distinct adult groups.
- Lower urinary tract infection causes dysuria, frequency, urgency and suprapubic discomfort without fever, flank pain or systemic illness.
- In women under 65, a symptom-led diagnostic approach is useful; vaginal discharge or irritation makes urinary infection less likely.
- Culture urine before treatment in pregnancy and men, and when recurrent, resistant-risk, atypical, severe or failing to improve.
- Do not screen or treat asymptomatic bacteriuria except in pregnancy and before selected urological procedures breaching mucosa.
- For non-pregnant women, NICE first choices include nitrofurantoin 100 mg modified-release twice daily for three days or trimethoprim 200 mg twice daily for three days when resistance risk is low.
- Men generally need a seven-day course and assessment for prostate involvement; nitrofurantoin is unsuitable when prostatitis is suspected.
- Use renal function, pregnancy, allergy, prior culture and recent antibiotic exposure to select a safe agent.
- Escalate symptoms that worsen rapidly or fail to begin improving within 48 hours, and reconsider pyelonephritis, STI and structural disease.
Key red flags
Fever, rigors, flank pain or costovertebral-angle tenderness suggests upper urinary tract infection.
Hypotension, tachypnoea, confusion, mottling or oliguria requires urgent sepsis assessment.
Pregnancy with urinary symptoms or bacteriuria requires prompt culture-guided treatment and obstetric-aware follow-up.
Male urinary symptoms with pelvic pain, retention or systemic illness may reflect acute prostatitis.
Persistent visible haematuria, recurrent atypical infection or treatment failure requires investigation beyond repeated antibiotics.
Fever, rigors, loin pain, vomiting or costovertebral-angle tenderness should be managed as possible pyelonephritis rather than uncomplicated cystitis.
Confusion, tachypnoea, hypotension, mottling, reduced urine output or elevated lactate requires urgent systemic assessment and hospital escalation.
Pregnancy increases maternal and fetal consequences, while male symptoms raise concern for prostatic involvement, obstruction and a complicated urinary source.
Investigation priorities
Estimate lower UTI probability and identify upper-tract, genital or systemic features.
Management branches
A non-pregnant woman has a convincing lower urinary syndrome without systemic, flank or vaginal features.
- Assess symptom combination, previous cultures, resistance risk, renal function and immediate allergy and give self-care and safety-net advice.
- Use nitrofurantoin 100 mg modified-release twice daily for three days when eGFR is at least 45 mL/minute, or trimethoprim 200 mg twice daily for three days when resistance risk is low.
- When first choices are unsuitable, use the current NICE alternatives and local susceptibility data rather than extending a convenient but ineffective course.
- Review if symptoms worsen at any time or do not begin improving within 48 hours; culture and reconsider upper-tract, STI and non-infective causes.