Overview
A urinary tract infection (UTI) is a bacterial infection affecting any part of the urinary system — kidneys, ureters, bladder, or urethra. Most UTIs involve the lower urinary tract (bladder and urethra) and are called cystitis. UTIs are far more common in women due to anatomy. While they are usually not serious when treated promptly, untreated UTIs can spread to the kidneys and become severe.
Causes and risk factors
The following factors are associated with the development of Urinary Tract Infection (UTI):
- Bacterial entry into urethra, usually Escherichia coli from gut
- Female anatomy — shorter urethra closer to anus
- Sexual activity — can introduce bacteria
- Urinary catheter use
- Menopause — reduced oestrogen affects urinary tract
- Kidney stones or enlarged prostate obstructing urine flow
- Weakened immune system
- Certain contraceptives (diaphragm, spermicides)
- Poor personal hygiene
Signs and symptoms
Common signs and symptoms of Urinary Tract Infection (UTI) include:
- Strong persistent urge to urinate
- Burning sensation when urinating
- Passing frequent small amounts of urine
- Cloudy urine
- Red, pink, or cola-coloured urine (blood in urine)
- Strong-smelling urine
- Pelvic pain in women
- Lower abdominal discomfort
- Fever and back pain if infection reaches kidneys
Diagnosis
Urinary Tract Infection (UTI) is typically diagnosed through a combination of medical history, physical examination, and appropriate investigations such as blood tests, imaging, or specialist review, depending on the specific condition and presentation. Your doctor will consider all relevant symptoms and risk factors before making a diagnosis.
Treatment options
Treatment approaches for Urinary Tract Infection (UTI) may include:
- Antibiotics: trimethoprim, nitrofurantoin, cefalexin
- Short course (3–7 days) for uncomplicated UTI
- Longer course if infection involves kidneys
- Increased fluid intake to flush bacteria
- Pain relief: paracetamol or ibuprofen
- Cranberry products — modest evidence for prevention
- Topical vaginal oestrogen for postmenopausal women with recurrent UTIs
- Prophylactic antibiotics for frequently recurring UTIs
Prevention
Drink plenty of water, wipe from front to back, urinate after sex, wear cotton underwear, avoid holding urine for long periods, change contraceptive method if UTIs are frequent.
Complications
If left untreated or poorly managed, Urinary Tract Infection (UTI) can lead to complications including:
Kidney infection (pyelonephritis), sepsis, recurrent UTIs, and — in pregnancy — risk of premature labour.
Sources and references: This article is written in accordance with NHS UK, WHO, and Mayo Clinic clinical guidelines. It is reviewed for accuracy by the SymptomSense content team. ICD-10 code: N39.0. Last reviewed June 2026.