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What is a urinary tract infections?

Urinary tract infections (or UTIs) are infections which can affect different parts of your urinary tract, including your bladder (‘cystitis’), urethra (‘urethritis’) or kidneys (‘pyelonephritis’).


Causes of urinary tract infections

UTIs are usually caused by bacteria from faeces in your gut (e.g. E. coli) colonising the skin around the opening of your urethra (the tube that carries urine out of your body) and then entering the urinary tract.

Anyone can get a UTI at any age but women are more prone to getting them because they have a shorter urethra than men, making it easier for bacteria to reach the bladder or kidneys and cause an infection.

It is estimated that around half of all women in the UK have had a UTI.

Risk factors of urinary tract infections

Your risk of getting a UTI increases if you:

  • are pregnant
  • have sex and use products containing spermicide
  • have a urinary catheter (a tube in your bladder used to drain urine)
  • have a family history of UTIs
  • have a condition that makes it difficult to fully empty your bladder – such as an enlarged prostate gland in men and constipation in children
  • have a condition that blocks your urinary tract – such as kidney stones
  • have vesicoureteric reflux – when the bladder contracts, allowing some urine back into the ureters rather than being sent down the urethra
  • have certain kidney conditions such as polycystic kidney disease.

Duration of infection

Although symptoms can feel uncomfortable and painful, mild UTIs (such as mild cases of cystitis) usually clear up within a few days and rarely cause long-term damage.

However, some severe forms of UTIs can lead to kidney infections, where the infection travels up the urinary tract into the kidneys. In very rare cases this type of infection can cause permanent kidney scars, which in turn can lead to kidney disease.

Kidney scars can sometimes be present from birth, and can make a person more susceptible to UTIs so sometimes it can be difficult to tell if a UTI has helped to cause kidney disease or whether it is a complication of the disease.

Urinary tract infections symptoms

Symptoms of a UTI include:

  • pain and/or a burning feeling on passing urine (some describe it as a sharp stinging feeling)
  • having a sudden urge to pass urine
  • feeling the need to pass urine more often
  • feeling that the bladder has not been emptied
  • foul smelling or cloudy urine
  • pain in the lower part of the abdomen (below the belly button)
  • possibly noticing blood in your urine (link to ‘blood in urine’ page in ‘about kidney disease’ section)
  • (in severe cases) fever, feeling generally unwell, muscle aches, and shivering
  • some elderly people may experience confusion and agitation
  • children may wet themselves or wet the bed and try to avoid passing urine because of the burning sensation.

Urinary tract infection treatment

Mild UTIs can often clear up on their own, especially if you drink lots of fluids to help flush bacteria out. Paracetamol can help to relieve pain. Anti-inflammatory drugs (e.g. Ibuprofen, Naproxen, Diclofenac) can help with symptoms but should be avoided by anyone with pre-existing kidney problems; they may increase the risk that the infection will spread to the kidneys.

See your GP if:

  • your symptoms have lasted for over five days or suddenly get worse
  • you are pregnant or have diabetes
  • you develop a high temperature
  • you are a man and you think you have a UTI
  • you have a child with symptoms of a UTI
  • you keep getting UTIs.

A urine test will probably be used to check that you have a UTI and antibiotics may be given to clear up the infection. Further tests may be needed if you have frequent urinary infections or if you also have high blood pressure, other abnormalities in the urine or are pregnant.

Searching for new treatments

The bacteria E. coli causes 85% of UTIs but more and more strains of E. coli are becoming resistant to antibiotics. This means that infections are becoming more difficult to treat so researchers are investigating ways to develop alternative treatments.

How to help yourself

Not all UTIs can be prevented but the best way to avoid them is to:

  • drink plenty of fluids
  • wipe from front to back after going to the toilet to prevent the spread of bacteria from the gut
  • empty your bladder as soon as you feel the urge and also as soon as possible after sex
  • avoid perfumed soaps and tight synthetic clothing
  • change children’s nappies frequently
  • make sure that your bladder is completely empty each time you pass urine: if you have a slow stream or tend to dribble at the end, take some time to let all the urine come away
  • particularly if you are known to have vesicoureteric reflux, try a technique called ‘double voiding’: after you pass urine, stand up and walk around for a few minutes. Then return to the toilet a few minutes to see if any more urine comes away. If it does, do this each time you pass urine.

Reviewed April 2019

Dr Rachel Floyd
Dr Rachel Floyd

"The research has the potential to tackle our approach to everyday UTIs”

Dr Rachel Floyd

Researcher spotlight

Dr Rachel Floyd has researched UTIs with the help of funding from from Kidney Research UK. The funding has helped support her team’s vital research project which looks at why some UTIs, often caused by E.coli, can become resistant to antibiotics.

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