Most urinary tract infections (UTIs) are caused by bacteria that live in the digestive system.

If these bacteria get into the urethra (the tube where urine comes out), they can cause infection.

It’s thought the bacteria can spread to the urethra via the anus. For example, if toilet paper touches your anus and then touches your genitals, the bacteria can multiply and move through your urinary tract, causing infection of your:

• urethra (urethritis)
• bladder (cystitis)
• ureters (ureteritis) – the ureters are tubes that run from the bladder to the kidneys
• kidneys (pyelonephritis)  

Who’s at risk of getting a UTI?

Women are more likely than men to have a UTI. This is because in women, the urethra is closer to the anus than it is in men. Also, the urethra is much shorter in women, making it easier for bacteria to reach the bladder.

You are also more likely to develop a UTI if you have:

• a condition that obstructs or blocks your urinary tract, such as kidney stones
• a condition that prevents you fully emptying your bladder (it’s easier for bacteria to multiply if urine stays in the bladder for too long)
• a weakened immune system – from chemotherapy or HIV, for example 
• a urinary catheter – a tube inserted into your bladder to drain away the urine

Further risk factors in women

Women are also more likely to get a UTI if: 

• they’re sexually active – having sex can irritate the urethra, allowing bacteria to travel through it more easily and into the bladder
• they use a diaphragm for contraception, as a diaphragm can put pressure on the bladder and prevent it emptying properly
• they use condoms coated in spermicide, as spermicide can irritate the vagina, making it more vulnerable to infection

Further risk factors in men

Men are also more likely to get a UTI if:

• they have an enlarged prostate gland – this can put pressure on the bladder and urethra, preventing the bladder emptying properly

Find out about:

• getting tested for a UTI
• UTI treatment

Complications of a UTI aren’t common, but they can be serious.

Complications usually only affect people with a pre-existing health condition, such as diabetes or a weakened immune system.

You’re also more likely to get complications from a UTI when you’re pregnant, so it’s important to tell a doctor if you are pregnant and have any of the symptoms of a UTI.

The complications of UTIs are discussed below.

Prostatitis

Men experiencing recurrent UTIs are at risk of complications that affect the prostate, such as prostatitis.

Prostatitis is inflammation (swelling) of the prostate gland, which can cause pain when urinating or ejaculating and general discomfort in the pelvic area.

A four-week course of antibiotics can be used to treat prostatitis and the symptoms usually pass within two weeks.

Read more about prostatitis.

Kidney infection

A kidney infection (pyelonephritis) can happen when bacteria travel from the bladder to the kidneys.

A kidney infection doesn’t usually pose a serious threat to your health if treated promptly, but it can make you feel very unwell. If a kidney infection isn’t treated, it can get worse and cause permanent kidney damage.

The symptoms often appear quickly, often within a few hours. You may feel feverish, shivery, sick and have a pain in your back or side.

Read more about the symptoms of a kidney infection and treating a kidney infection.

Kidney failure

Kidney failure is when the kidneys stop working properly. If a person has kidney failure (also known as renal failure), they may need to have artificial kidney treatment, called dialysis.

Find out more about dialysis.

Blood poisoning

Blood poisoning (sepsis) is a rare but potentially fatal complication of kidney infection. It happens when bacteria spread from the kidneys into the bloodstream.

Once bacteria are in your blood, the infection can spread to any part of your body, including the major organs.

Blood poisoning is a medical emergency that usually requires admission to a hospital intensive care unit (ICU) while antibiotics are used to fight the infection.

Find out more about the symptoms of blood poisoning and treating blood poisoning.

A urinary tract infection (UTI) is diagnosed using a urine test, which can detect bacteria and blood in the urine.

However, if you’re a woman and you have the typical symptoms of a lower UTI, your doctor will probably be able to make a diagnosis just by asking about your symptoms. 

When you need further tests

You won’t usually need further testing unless your symptoms don’t get better with treatment, or you keep getting UTIs that could be caused by abnormalities in your urinary tract.

Further testing is also recommended if:

• you have a suspected upper UTI – these have a higher risk of complications than lower UTIs
• there is blood in your urine – this could be a symptom of other conditions
• you’re a man – UTIs are uncommon in men, so it’s important to rule out other possible causes of the symptoms
• you’re pregnant – pregnant women have a slightly higher risk of developing complications
• it’s likely you’ll develop complications – for example, if you have a weakened immune system

Initial testing involves taking a sample of urine and testing it for bacteria. This confirms the diagnosis and is useful for deciding which antibiotics will be best for your treatment.

Other tests

Other tests that may be needed include:

• a CT scan of your urinary tract (urogram)
• a cystoscopy
• an ultrasound scan

CT urogram

A computerised tomography (CT) scan uses X-rays and a computer to create detailed images of the inside of the body.

The scan is painless and will usually take 5 to 10 minutes.

Read about how a CT scan is performed.

Cystoscopy

During a cystoscopy, a special instrument called a cystoscope (a thin, flexible telescope) is passed into your body so the urologist (urinary tract specialist) can look inside your bladder.

A special jelly that contains local anaesthetic will be put into the opening of your urethra to numb the area and help the cystoscope pass into the urethra more easily.

A cystoscopy usually takes 5 to 10 minutes to carry out. The urologist will study the lining of your bladder and urethra to identify any abnormalities.

Ultrasound scan

An ultrasound scan may be used to rule out conditions such as:

• bladder stones
• kidney stones
• a blockage in the urinary tract

An ultrasound scan is a painless procedure that uses high-frequency sound waves to create an image of part of the inside of the body. It usually takes around 15 to 45 minutes.

Find out more about:

• symptoms of a UTI
• UTI treatment
• preventing UTIs

Urinary tract infections (UTIs) are very common. They can be painful and uncomfortable, but they usually pass within a few days or can be easily treated with a course of antibiotics.

UTIs are more common in women than in men. It’s estimated half of all women in the UK will have a UTI at least once in their life, and 1 in 2,000 healthy men will develop one each year.

Children can also get UTIs, although this is less common. Read more about UTIs in children.

If you develop a UTI, you’re likely to feel:

• pain or a burning sensation when urinating (doctors refer to this as dysuria)
• a need to urinate often
• pain in the lower abdomen (tummy)

Find out more about UTI symptoms.

When to see your GP

You may find your UTI symptoms are mild and pass within a few days. However, if you find your symptoms very uncomfortable or if they last for more than five days, see your GP.

Also see your GP if you have a UTI and:

• you develop a high temperature
• your symptoms suddenly get worse
• you are pregnant
• you have diabetes

Treating UTIs

Urinary tract infections usually get better on their own within four or five days.

Antibiotics can help speed up recovery time and are usually recommended for women who keep getting UTIs. In some cases, long-term use of antibiotics help prevent the infection returning.

Complications of a UTI aren’t common, but can be serious and lead to kidney failure or blood poisoning.

These complications usually only affect people with a pre-existing health problem, such as diabetes or a weakened immune system (the body’s natural defence against infection).

Men with a recurrent UTI are at risk of prostatitis (inflammation of the prostate).

Read more about how UTIs are treated.

What is the urinary tract?

The urinary tract is where our bodies make and get rid of urine. It’s made up of:

• the kidneys – two bean-shaped organs, about the size of your fists, that make urine out of waste materials from the blood
• the ureters – tubes that run from the kidney to the bladder
• the bladder – where urine is stored until we go to the toilet
• the urethra – the tube from the bladder through which urine leaves the body

What causes a UTI?

A UTI develops when part of the urinary tract becomes infected, usually by bacteria. Bacteria can enter the urinary tract through the urethra or, more rarely, through the bloodstream.

There is usually no obvious reason why the urinary tract gets infected, although some women find they develop a UTI after having sex.

UTIs are not sexually transmitted infections (STIs), but irritation from having sex can sometimes trigger a UTI.

UTIs in men are far less common than in women and need investigating to find an underlying cause. These causes may include narrowing of the urethra (a stricture), a previous STI, a bladder stone, or a problem with the prostate gland. 

Read more about what causes a UTI.

Emptying your bladder after sex, wiping from front to back after going to the toilet, avoiding constipation and drinking cranberry juice are all thought to reduce your risk of developing a urinary tract infection.

Read more about preventing a UTI.

Different types of UTI

You can get an infection in the lower (bladder and urethra) or upper (kidney and ureters) part of the urinary tract, and doctors often describe them as lower or upper UTIs.

Upper UTIs are potentially more serious than lower UTIs because there is a risk of kidney damage.

An infection of the bladder is called cystitis, while an infection of the urethra is known as urethritis.

Not all urinary tract infections (UTIs) can be prevented, but there are some steps you can take to reduce your risk of developing an infection.

Cranberry juice and capsules

Drinking cranberry juice may help prevent UTIs. If you have had recurring UTIs, higher-strength cranberry capsules are recommended. These are available from most pharmacists and supermarkets.

Don’t drink cranberry juice or take cranberry capsules if you are taking warfarin (a medicine used to prevent blood clots).

Treat constipation promptly

Constipation can increase your chances of developing a UTI. Recommended treatments for constipation include:

• increasing the amount of fibre in your diet (20g to 30g of fibre a day)
• using a mild laxative on a short-term basis
• drinking plenty of fluids

See your GP if your symptoms don’t improve or if your child is constipated.

Diaphragms and condoms

If you’re a woman, using a diaphragm for contraception can increase the risk of getting a UTI. This is because the diaphragm may press on your bladder and prevent it emptying completely when you urinate.

If you use a diaphragm and have recurring UTIs, you might want to consider changing to another method of contraception. There are 15 different methods of contraception to choose from.

If you get recurring UTIs and you use condoms, try using condoms that don’t have a spermicidal lubricant on them – it will say whether it does on the packet.

Spermicidal lubricant can cause irritation and make it more likely that you’ll get a UTI. There are lots of condoms that have non-spermicidal lubricant, so use these instead.

Other useful advice

The following advice may be useful in helping you keep your bladder and urethra free from bacteria:

• drink plenty of water to avoid dehydration and help clear bacteria from the urinary tract
• go to the toilet as soon as you feel the need to urinate, rather than holding it in
• wipe from front to back after going to the toilet
• practise good hygiene by washing your genitals every day, and before having sex
• empty your bladder after having sex

The Map of Medicine is used by doctors throughout the NHS to determine the best treatment options for their patients. NHS Choices offers everyone in England exclusive and free access to this cutting-edge internet resource, which lets you see exactly what your doctor sees.

The information in the Map has been approved by the UK’s leading clinical experts, is based on the best available clinical evidence, and is continually updated. To take advantage of this unique resource go to:

Map of Medicine: lower urinary tract infection (UTI) in males

The symptoms of an infection in your upper urinary tract (kidney and ureters) are different from symptoms of infection in your lower urinary tract (bladder and urethra).

However, in some cases you may notice the symptoms of both, as one can spread to the other.

Symptoms of a UTI are similar to those of many other conditions and don’t necessarily mean you have an infection.

Symptoms of a lower UTI can include:

• urethral syndrome – this includes needing to urinate more often, a constant, dull pain in the pubic region, and pain when urinating (dysuria)
• cloudy urine or blood in your urine (haematuria)
• urine that smells unusually unpleasant
• back pain
• a general sense of feeling unwell

Symptoms of an upper UTI can include: 

• a high temperature (fever) of 38ºC (100.4ºF) or above
• uncontrollable shivering
• nausea (feeling sick)
• vomiting
• diarrhoea

With an upper UTI you may also notice pain in your side, back or groin. The pain can range from moderate to severe, and it is often worse when you’re urinating.

When to seek medical advice

There is a higher risk of complications with an upper UTI, so see your GP if you notice any of the symptoms.

Although many lower UTIs are mild and get better within a few days, speak to your GP if your symptoms are causing you a lot of pain and discomfort or if they last more than five days.

Increased risk of complications

There are some risk factors that increase your risk of more serious complications from a UTI. These include:

• kidney disease
• type 1 diabetes or type 2 diabetes
• a weakened immune system caused by treatment such as chemotherapy or a health condition such as HIV
• an object in your urinary tract, such as a kidney stone or catheter (a thin tube inserted by a health professional into the urethra to drain the bladder)
• being pregnant
• being over 65 years old

See your GP if any of these apply to you and you notice symptoms of a UTI.

Find out more about complications of a UTI.

Your treatment will depend on whether your infection is in the upper or lower urinary tract.

Both types of urinary tract (UTI) infection can usually be treated at home using a course of antibiotics.

If an upper UTI is more serious or you are also at increased risk of complications, you’ll need hospital treatment.

Self-help

You can also use over-the-counter painkillers such as paracetamol to help with any pain.

However, if you have an upper UTI, don’t use non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen. These types of drugs can increase the risk of you developing kidney complications.

Make sure you drink plenty of fluids, as this will help to relieve any symptoms of fever and prevent dehydration.

Hospital treatment for a UTI

You may need to go into hospital to be treated for an upper urinary tract infection if you: 

• are pregnant
• are over 60 years old
• have severe vomiting
• have severe pain 
• are dehydrated
• can’t pass urine, or you’re passing smaller amounts of urine than usual
• have a blockage in your kidneys, such as a kidney stone
• have diabetes
• have been having chemotherapy or radiotherapy
• have a history of kidney disease
• have a history of recurring upper UTIs
• have HIV
• have sickle cell anaemia
• have cancer

If you’re admitted to hospital with an upper UTI, you’ll probably have a drip put in your arm to give you fluids. This is to help keep you hydrated. You can also be given antibiotics through the drip.

You’ll have regular blood and urine tests to monitor your health and see how well the antibiotics are fighting off the infection.

Most people who are treated for an upper UTI respond well to treatment and can leave hospital within three to seven days.

Recurring UTIs

Unfortunately, some people keep getting UTIs. This is called having recurring UTIs.

Recurring UTIs can happen because the urethra gets irritated after having sex. If it’s thought this might be the cause of your recurring UTIs, you may be given antibiotic tablets to take after each time you have sex.

Using a diaphragm for contraception or using condoms coated with spermicide can increase the risk of getting a UTI. Find out more about diaphragms, condoms and UTIs in preventing UTIs.

If your recurring UTIs are not thought to be linked to having sex, you may be given a low-dose antibiotic to take every day.

If you can’t take antibiotics

Taking methenamine hippurate is an alternative to antibiotics. Methenamine hippurate works by changing the chemical composition of your urine, making it “less attractive” to bacteria.

Side effects of methenamine hippurate are uncommon. However, they can include: 

• skin rashes
• itchy skin
• indigestion

Methenamine hippurate isn’t as effective as antibiotics in preventing the infection returning. Because of this, it tends to be used only when people can’t or won’t take antibiotics.

There are also some lifestyle changes you can make to reduce the risk of getting a UTI. Find out more about how you can prevent UTIs.