Urinary Tract Infection
Bacterial infection of the bladder or kidneys causing burning, frequency and urgency.
Overview
UTIs are very common, especially in women. Uncomplicated cystitis is treated with a short course of antibiotics. Fever, loin pain or vomiting suggests pyelonephritis and needs urgent assessment.
Symptoms
- • Burning on urination
- • Frequency and urgency
- • Cloudy or smelly urine
- • Lower abdominal pain
- • Visible blood in urine
Risk factors
- • Female sex
- • Sexual activity
- • Pregnancy
- • Diabetes
- • Urinary catheter
- • Postmenopausal status
Causes
- • E. coli (most common)
- • Other Gram-negative bacteria
- • Catheter-associated infection
🚨 Red flags — seek urgent care
- • Fever and loin pain (pyelonephritis)
- • Vomiting and inability to drink
- • Symptoms in pregnancy
- • Confusion in older adults
When to seek care
- • Symptoms not improving in 48 hours
- • Any red flag
- • Recurrent infections (>3 per year)
Diagnosis
- • Lower UTI in non-pregnant women: clinical diagnosis from dysuria, frequency, urgency, suprapubic pain
- • Urine dip (nitrites + leucocytes) supports diagnosis; not required if symptoms classic
- • MSU culture for: men, pregnancy, recurrent UTI, treatment failure, suspected pyelonephritis, catheter-related
- • Imaging (USS/CT KUB) and urology referral if recurrent or suspected obstruction
Treatment
- • Non-pregnant women: nitrofurantoin 100 mg modified-release BD for 3 days (or trimethoprim 200 mg BD 3 days where local resistance allows)
- • Pregnancy: 7-day course — nitrofurantoin (avoid at term), cefalexin, or amoxicillin (per culture)
- • Men: 7 days nitrofurantoin or trimethoprim
- • Pyelonephritis: 7–10 days co-amoxiclav, ciprofloxacin or trimethoprim; hospital IV antibiotics if systemically unwell
- • Increase fluids; consider methenamine hippurate or vaginal oestrogens for recurrent UTI
Prevention
- • Adequate hydration (1.5–2 L/day)
- • Wipe front-to-back; void after intercourse
- • Cranberry products and D-mannose — limited evidence
- • Vaginal oestrogens for postmenopausal recurrent UTI
Complications
- • Pyelonephritis and renal scarring
- • Urosepsis and septic shock
- • Preterm labour in pregnancy
- • Recurrent infections affecting quality of life
Education & self-care
This guidance is reviewed by Dr. Handel Emery, MD, FRCP (UK) and last updated 2026-06-08. It is educational and not a substitute for professional medical advice.
Frequently asked questions
Does cranberry prevent UTIs?
Evidence is modest. Adequate fluid intake and post-coital voiding are the most consistently helpful measures.
Do I always need antibiotics?
Many mild lower UTIs in otherwise healthy women settle with hydration and analgesia, but symptomatic infections usually benefit from a short antibiotic course. Pyelonephritis and male UTIs always require antibiotics.
How can I prevent recurrent UTIs?
Good hydration, voiding after sex, vaginal oestrogen in postmenopausal women, and (in some) D-mannose or low-dose prophylactic antibiotics reduce recurrence.
When are urine tests needed?
In pregnancy, men, children, recurrent UTIs, suspected pyelonephritis or treatment failure. Otherwise, in non-pregnant women with classic symptoms, empirical treatment without culture is often appropriate.