What a UTI Is

A UTI happens when bacteria enter and irritate the bladder or urinary tract. The most common areas affected include:

  • The bladder (cystitis)
  • The urethra (urethritis)
  • The kidneys (less common, and usually linked with more severe symptoms)

The most common organism associated with UTIs is E. coli, a bacterium normally found in the gut. Most UTIs are simple and improve with treatment and hydration.d most cases improve without treatment.

Organism Notes
E. coli The most common cause of simple bladder infections. Often linked to natural bacteria from the gut.
Klebsiella species Occasionally found in UTIs. More common in people with certain health conditions.
Proteus species Can cause irritation or strong-smelling urine. Sometimes linked with recurrent infections.
Enterococcus Less common cause. May appear in people with long-term urinary symptoms.
Staphylococcus saprophyticus Occasionally affects younger adults. Can cause similar symptoms to other UTIs.

Common Symptoms of a UTI

You may experience:

  • Burning or stinging when passing urine
  • Needing to pass urine more often
  • Passing small amounts more frequently
  • Cloudy, dark or strong-smelling urine
  • Lower tummy or pelvic discomfort
  • Feeling suddenly and urgently need to urinate
  • Mild back discomfort
  • Feeling generally unwell

Not all symptoms mean infection, and symptoms can overlap with other causes of urinary discomfort. Urinary tract infections can affect men and women.

Common Reasons to Have a UTI Reviewed by a GP

Speak to a GP if you have:

  • Your symptoms last more than 24 to 48 hours
  • You have recurrent UTIs
  • Symptoms keep returning soon after treatment
  • There is blood in your urine
  • You have new back or side pain
  • You have pelvic discomfort that is not improving
  • You are pregnant and have urinary symptoms
  • You have diabetes or long-term health conditions
  • You have a catheter or have recently had a procedure affecting your urethra

A GP can assess symptoms, arrange a urine dipstick or culture if needed and advise on safe treatment options.

Simple lower UTI (common pattern)

  • burning or stinging when passing urine
  • needing to go more often
  • cloudy or strong-smelling urine
  • mild lower tummy discomfort

These symptoms usually improve gradually over time.

Symptoms that may need a GP review

  • symptoms lasting longer than expected
  • urinary symptoms with back pain
  • blood in urine
  • recurrent UTIs
  • symptoms after recent treatment
  • urinary symptoms in men, children or pregnancy

A GP can guide you on treatment or further assessment if needed.

Bacterial Causes and When Antibiotics May Be Considered

The majority of UTIs are caused by bacteria such as E. coli, which can irritate the bladder lining.

Antibiotics may be considered when:

  • symptoms are significant or persistent
  • dipstick or culture tests support infection
  • symptoms are affecting daily activities
  • there is fever or flank discomfort
  • you are in a group where early treatment is recommended (for example pregnancy, diabetes or recurrent infections)

Not all urinary symptoms are caused by infection, and antibiotics are not always required. A GP will assess your symptoms, medical history and test results (if needed) before advising treatment.


Further Reading and Hub Links

Visit our Common Infections hub or browse more health topics in the AccessGP Knowledge Base.

If you would like to discuss UTI symptoms, recurring infections or bladder discomfort, you can book an online GP appointment with AccessGP.

Last reviewed by Dr Zamiel Hussain, GMC registered GP
Updated: 8 December 2025