Urinary tract infections (UTIs or pokenga pūaha mimi) can affect any part of your urinary system – kidneys, ureters, bladder or urethra. UTIs are also known as cystitis or bladder infections.

Key points about UTIs

  1. About 1 in every 2 women will have at least one UTI in their lifetime. The most common is cystitis, an infection that affects your bladder.
  2. Symptoms of a UTI include burning or pain when peeing and needing to pee more often and more urgently.
  3. UTIs can be treated with antibiotics, but they are not always needed.
  4. Self-care includes taking pain relief and drinking plenty of water. There is no strong evidence that cranberry products help.
  5. In rare cases, the infection can spread to your kidneys. This is known as pyelonephritis and needs urgent medical care.

See other pages for UTIs in pregnancy, UTIs in men and UTIs in children.

What is a UTI?

A UTI is a bacterial infection in some part of your urinary system. Your urinary system includes all the organs involved in making and releasing urine (pee): 

  • Kidneys – these filter your blood to remove waste and extra water to make urine (pee).
  • Ureter – two thin tubes of muscle, one on each side of your bladder, through which urine flows from your kidneys to your bladder.
  • Bladder – where you store urine until you need to pee.
  • Urethra – when you pee, urine passes along your urethra, a central tube that carries urine out of your body. 

When the infection is just in the bladder (cystitis) and urethra (urethritis), this is called a lower UTI. If it travels up to affect one or both kidneys as well (pyelonephritis) then it is called an upper UTI. This can be more serious than a lower UTI, as the kidneys can become damaged by the infection.

What causes a UTI?

An infection in your urinary system may be caused by: 

  • sexual intercourse
  • problems in the structure of your kidneys, bladder or tubes
  • irritation of the urethra by chemicals (eg, soaps, perfumes, vaginal hygiene sprays, spermicidal tubes)
  • ulcers or inflammation near your urethra
  • unprotected sex
  • sexually transmitted infection (STI), eg, chlamydia
  • radiation therapy which can irritate the lining of the bladder
  • bacteria from your anal area (bottom) entering your bladder via your urethra – the urethra is shorter in women than in men so it is easier for bacteria to reach the bladder and cause infection in women. The picture below shows how this can happen.

Travel of bacteria from rectum to urethra. Image credit: 123rf

Who is at risk of developing a UTI?

UTIs can occur at any age and are more common if you:

  • are pregnant (read more about UTI in pregnancy)
  • have had UTIs in the past
  • have diabetes, kidney failure or a weakened immune system
  • have other urinary tract problems such as urinary stones or inadequate emptying of the bladder
  • have a condition that makes it difficult to fully empty the bladder such as constipation
  • have been through menopause – the changes in the tissues of your vagina and urethra after menopause make it harder for them to defend against infection
  • use a urinary catheter (a long, thin tube used to drain urine)
  • engage in unsafe sex.

What are the symptoms of a UTI? 

If you have any symptoms of a UTI, you should see a doctor. Your symptoms could mean that you have a UTI or another condition like an STI or pyelonephritis.

Symptoms of a UTI include:

  • pain or burning during or immediately after peeing (dysuria)
  • needing to pee more often than usual during the night (nocturia)
  • pain in your lower tummy (abdomen)
  • feeling the need to pee more often
  • needing to pee without much notice
  • suprapubic pain (pain just above your pubic bone)
  • recent antibiotic use
  • urine that smells bad or looks cloudy or reddish.

Older women may have no symptoms or fever. Often the only symptoms are being more muddled, sleepier, incontinent, off your food, or just feeling generally unwell. Confusion and sleepiness can put older adults at risk of falls.

Call Healthline or see your doctor urgently if you have any of the following symptoms: 
a very high temperature, or you’re feeling hot and shiverya very low temperature below 36ºCconfusion, drowsiness or you have difficulty speakingyou have not been for a pee all daypain in the lower tummy or in the back, just under the ribsblood in your peeThese symptoms suggest a kidney infection (pyelonephritis), which can be serious if it’s not treated quickly.

How is a UTI diagnosed?

To diagnose a UTI, your GP will examine you and ask you questions about your general health. Sometimes that might be enough to diagnose a UTI. Your doctor may want you to provide a urine sample to identify what bacteria is causing the infection. Your doctor may also do a blood test and check your temperature and heart rate. 

How is a UTI treated?

The main aims of treatment are to relieve your symptoms, treat the infection and prevent the infection spreading to your kidneys.


UTIs are treated with antibiotics, the common ones being nitrofurantoin, cefalexin and trimethoprim. Usually, a 3–5 day course of antibiotics is needed to treat the infection and to reduce the risk of it spreading to your kidneys and causing pyelonephritis. Your symptoms should begin to improve within the first 2 days of taking antibiotics.

If your doctor advises you to take antibiotics, it’s important to finish the whole course of antibiotics, even if you start to feel better before the course is finished. If your symptoms continue for more than 2 days after starting treatment, or if you get worse, see your doctor as soon as possible.

If you have recurrent UTIs (you keep getting them), or are at higher risk of complications, your doctor may give you a low dose antibiotic to take for a few months. How long you need to take the antibiotic depends on how often you are having UTIs.

Can I get antibiotics for a UTI from my pharmacy without a prescription?

Many pharmacists are now able to sell an antibiotic called trimethoprim for the treatment of UTIs in women. This is available without a prescription if you are a woman aged 16–65 years, you’re not pregnant and you don’t have any other complicating factors.

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