Urinary tract infections (UTIs) occur due to microbes such as bacteria overcoming the body’s defenses in the urinary tract. They can affect the kidneys, bladder, and the tubes that run between them.

UTIs are one of the most common types of outpatient infections in the United States, leading to more than 8.1 million visits to the doctor every year.

The urinary tract consists of the upper and lower urinary tract. The kidneys and ureters make up the upper urinary tract, and the urethra and bladder make up the lower urinary tract.

UTIs have different names depending on where they occur. For example:

  • A bladder infection is called cystitis.
  • A urethra infection is known as urethritis.
  • A kidney infection is called pyelonephritis.

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The United Kingdom’s National Health Service (NHS) notes that symptoms can depend on whether a person is experiencing an upper or lower urinary tract infection.

In adults

Lower UTIs affect the bladder or urethra and can cause:

  • a frequent need to urinate
  • pain, discomfort, or burning sensation when urinating
  • a sudden urge to urinate
  • cloudy, strong-smelling urine that may contain blood
  • the sensation that the bladder is not fully empty
  • feeling unwell, tired, and achy

Upper UTIs affect the kidneys and ureters. As well as the symptoms above, they can cause:

  • a fever of 100.4ºF (38ºC) or higher
  • confusion
  • agitation
  • restlessness
  • pain in the back and sides
  • chills and shivering
  • nausea and vomiting

In males

Males and females share the same symptoms. However, 2021 research suggests that males had a higher chance of experiencing symptoms that affect the lower urinary tract.

It is worth noting that this study involved 1,256 people from a single community in Japan, so the findings may not apply to other populations.

In children

Additional symptoms in children include:

  • a high temperature
  • appearing generally unwell — for example, babies may appear irritable and not feed well
  • vomiting
  • wetting the bed or themselves

In older adults or those with a catheter

Additional symptoms of UTIs in older adults or those with a urinary catheter include:

  • wetting themselves
  • new shivering
  • new shaking
  • agitation
  • confusion

The Urology Care Foundation notes that different bacteria live on the skin or around the rectum and vagina. When the bacteria enter the urethra, it can travel to the bladder.

According to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), the body usually flushes out the bacteria before reaching a person’s bladder. However, in some cases, the body is unable to do so, resulting in a UTI.

UTIs most commonly occur due to the following bacteria:

  • Escherichia coli
  • Protus mirabilis
  • Enterococcus faecalis
  • Staphylococcus saprophyticus
  • Klebsiella pneumoniae

People of any age and sex can develop a UTI. However, some people are more at risk than others.

The following factors can increase the likelihood of developing a UTI:

  • being sexually active
  • having difficulty fully emptying the bladder
  • having a condition that causes a blockage in the urinary tract, such as kidney stones
  • having diabetes
  • having recently used a catheter
  • having had a previous UTI
  • having vesicoureteral reflux, a condition that causes the urine to flow backward
  • having poor hygiene

In females

The NIDDK notes that females are more likely to develop UTIs than males. This is because females have a shorter urethra, meaning the bacteria have less distance to travel to the bladder.

Additionally, the urethra is closer to the rectum, where the UTI-causing bacteria is present.

Going through menopause and using birth control methods, such as diaphragms or spermicide, can also increase the chance of developing a UTI.

Is pregnancy a risk factor for a UTI?

According to the American College of Obstetricians and Gynecologists, pregnant people have a higher risk of UTIs than other people.

Changes in the body during pregnancy can cause changes in the urinary tract.

Learn more about UTIs in pregnancy here.

In males

Males share the same risk factors for developing a UTI. However, having an enlarged prostate is a male-specific risk factor.

An enlarged prostate can block or obstruct the usual flow of urine.

In some cases, lower UTIs can lead to pyelonephritis. This is a sudden and severe kidney infection.

Symptoms include:

  • fever
  • flank pain
  • vomiting
  • nausea
  • burning urination
  • increased frequency and urgency to urinate
  • fatigue
  • shaking
  • chills
  • mental changes

If a person suspects they have a kidney infection, they should seek medical attention as soon as possible.

Recurrent or long-lasting kidney infections can cause permanent damage. Some sudden kidney infections can be life threatening, particularly if bacteria enter the bloodstream in a condition known as septicemia.

They can also increase the risk of pregnant people delivering infants prematurely or with a low birth weight.

There are several measures that an individual can take to reduce the risk of developing a UTI, including:

  • drinking 6–8, 8-ounce glasses of water per day
  • emptying the bladder fully when urinating
  • urinating after sex
  • wearing loose-fitting clothing and cotton underwear
  • keeping the genital area clean
  • avoiding the use of perfumed products on the genitals

The Centers for Disease Control and Prevention (CDC) suggests taking showers instead of baths and avoiding douching.

Females should also wipe from the front to the back to help avoid spreading the germs from the rectum to the vagina. In addition, if a person experiences frequent or recurring UTIs, they should talk with a doctor about switching birth control methods.

The American College of Obstetricians and Gynecologists mentions that cranberry pills and unsweetened cranberry juice may help decrease the chance of contracting UTIs. However, research is ongoing.

Individuals should contact a doctor if they develop UTI symptoms, especially if they have developed symptoms of a potential kidney infection.

A doctor will usually diagnose a UTI after asking about a person’s symptoms and testing a urine sample to assess the presence of white blood cells, red blood cells, and bacteria.

In some cases, a doctor may culture the urine to identify the type of bacteria causing the infection.

If someone has recurrent UTIs, a doctor may request further diagnostic testing to determine if anatomical or functional issues are the cause. Such tests may include:

  • Diagnostic imaging: This involves assessing the urinary tract using ultrasound, CT and MRI scanning, radiation tracking, or X-rays.
  • Urodynamics: This procedure determines how well the urinary tract stores and releases urine.
  • Cystoscopy: This allows the doctor to see inside the bladder and urethra with a camera lens inserted through the urethra via a long thin tube.

A healthcare professional will prescribe antibiotics to treat UTIs, regardless of a person’s sex.

The type of medication and length of treatment will depend on a person’s symptoms and medical history.

People should always complete the full course of treatment to make sure that the infection is fully clear and reduce the risk of antibiotic resistance. UTI symptoms can disappear before the infection has completely gone.

To cure a UTI that has occurred due to problems within the urinary system, a healthcare professional will need to diagnose the underlying issue.

If the person is seriously ill, they may need to be admitted to a hospital to ensure they consume sufficient fluids and receive the correct medication.

People may also need to go to the hospital if they are:

  • pregnant and are otherwise ill
  • an older adult
  • have cancer, diabetes, multiple sclerosis, spinal cord injury, or other medical problems
  • have kidney stones or other changes in their urinary tract
  • recovering from recent urinary tract surgery

To help treat and prevent recurrent UTI infections, a healthcare professional may:

  • suggest changing birth control methods
  • prescribe a single daily dose of antibiotics for 6–12 months
  • prescribe a single dose of antibiotics to take each time a person has sex

There are several suggested remedies that people with a UTI can try at home.

The NIDDK says drinking fluids and urinating frequently can help flush bacteria from the body, and using a heated pad for short periods can help relieve discomfort.

A person should contact a doctor if they develop symptoms of a UTI. Without treatment, UTIs can lead to a sudden and severe kidney infection which can be life threatening.

The NIDDK advises people to seek care immediately if they develop:

  • severe pain in the back near the ribs or lower abdomen
  • vomiting
  • nausea
  • fever

A UTI is an infection of the urinary tract. The urethra and bladder make up the lower urinary tract, and the upper urinary tract consists of the kidneys and ureters.

The main symptoms include a burning sensation during urination and a frequent and intense urge to urinate. The symptoms are the same for both males and females. However, males are more likely to experience the sensation that they have not finished urinating and urine dribbling from the penis after urination.

UTIs occur due to bacteria present on the skin and around the rectum and vagina. However, some risk factors are female- or male-specific.

Treatment includes antibiotics, and a person should drink plenty of fluids.

If an individual notices symptoms of a UTI, they should contact a healthcare professional. Without treatment, a kidney infection can occur.

Read the article in Spanish.