Bladder Infection (Urinary Tract Infection) in Adults

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Definition & Facts

In this section:

What is a bladder infection?

A bladder infection is an illness caused by bacteria. Bladder infections are the most common type of urinary tract infection (UTI).1 A UTI can develop in any part of your urinary tract, including your urethra, bladder, ureters, or kidneys.

Your body has ways to defend against infection in the urinary tract. For example, urine normally flows from your kidneys, through the ureters to your bladder. Bacteria that enter your urinary tract are flushed out when you urinate. This one-way flow of urine helps to keep bacteria from infecting your urinary tract. Learn more about your urinary tract and how it works.

Sometimes your body’s defenses fail and the bacteria may cause a bladder infection. If you have bladder infection symptoms, see a health care professional.

Most of the time, getting treatment right away for an infection in your urethra or bladder can prevent a kidney infection. A kidney infection can develop from a UTI that moves upstream to one or both of your kidneys. Kidney infections are often very painful and can cause serious health problems, so it’s best to get early treatment for a UTI.

When a bladder infection or other UTI is diagnosed and treated properly, most people won't have complications.

The urinary tract, showing the kidneys, ureters, bladder, and urethra.Most UTIs occur in the bladder. In a few cases, an infection can spread to one or both kidneys.

Is there another name for a bladder infection?

Bladder infections are also called cystitis. Sometimes people use the more general term, urinary tract infection (UTI), to mean a bladder infection, although UTIs can occur in other parts of the urinary system. UTIs that occur in the urethra only are called urethritis. A kidney infection is called pyelonephritis.

How common are bladder infections?

Bladder infections are common, especially among women. Research suggests that at least 40 to 60 percent of women develop a UTI during their lifetime, and most of these infections are bladder infections. One in 4 women is likely to have a repeat infection.1

Who is more likely to develop a bladder infection?

People of any age or sex can develop bladder infections, but women are at higher risk than men. Some people are more prone to getting these infections than others, especially those who have certain medical conditions or lifestyle factors.

You are more likely to develop a bladder infection if you

  • are sexually active
  • are a woman who has gone through menopause
  • are a woman who uses certain types of birth control, such as diaphragms or spermicide
  • have trouble emptying your bladder completely, like people with a spinal cord injury or nerve damage around the bladder
  • have a problem in your urinary tract that blocks, or obstructs, the normal flow of urine, such as a kidney stone or enlarged prostate
  • have an abnormality of the urinary tract, such as vesicoureteral reflux (VUR)
  • have diabetes or problems with your body’s immune, or natural defense, system
  • recently used a urinary catheter
  • had a UTI in the past

Women are more likely to develop a bladder infection than men, mainly due to differences in anatomy:

  • Women have a shorter urethra than men, which means bacteria have a shorter distance to travel to reach and infect a woman’s bladder.
  • In women, the opening to the urethra is closer to the rectum, where the bacteria that cause bladder infections live.
A young woman talks with a health care professional who is wearing a stethoscope.
People of any age or sex can develop a bladder infection. However, women are much more likely to develop this type of infection than men.

What are the complications of bladder infections?

If infections in the lower urinary tract, such as bladder infections, are not treated, they can lead to kidney infections. If you have a kidney infection, a health care professional will provide treatment to relieve your symptoms and help prevent complications.

Health care professionals routinely test pregnant women for bacteria in the urine because a bladder infection during pregnancy is more likely to become a kidney infection.

Complications from bladder infections are rare when you work with your health care provider to find the best treatment and complete it. If your infection is treated with antibiotics, it’s important to follow directions carefully and finish all the medicine, even after you start to feel better. If you stop taking antibiotics too soon, you may get another infection that is harder to treat.


Symptoms & Causes

What are the symptoms of a bladder infection?

Symptoms of a bladder infection may include

  • a burning feeling when you urinate
  • frequent or intense urges to urinate, even when you have little urine to pass

Seek care right away

If you have symptoms of a bladder infection, see a health care professional right away, especially if you have severe pain in your back near your ribs or in your lower abdomen, along with vomiting and nausea, fever, or other symptoms that may indicate a kidney infection.

Kidney infections are often very painful and can cause serious health problems, so it’s best to get early treatment.

What causes a bladder infection?

Most of the time a bladder infection is caused by bacteria that are normally found in your bowel. The bladder has several systems to prevent infection. For example, urination most often flushes out bacteria before it reaches the bladder. Sometimes your body can’t fight the bacteria and the bacteria cause an infection. Read the reasons you may be at risk for UTIs.


How do health care professionals diagnose a bladder infection?

Health care professionals use your medical history, a physical exam, and tests to diagnose a bladder infection.

A health care professional will ask if you have a history of health conditions that make you more likely to develop any type of UTI. During a physical exam, the health care professional will ask you about your symptoms.

A woman sits on an examining table and talks to a health care professional.
Health care professionals use your medical history, a physical exam, and tests to diagnose a bladder infection.

Which tests do health care professionals use to diagnose a bladder infection?

Health care professionals typically test a sample of your urine to diagnose a bladder infection. In rare cases, a health care professional may also order another test to look at your urinary tract.

Lab tests

Urinalysis. You will collect a urine sample in a special container at a doctor’s office or at a lab. A health care professional will test the sample for bacteria and white blood cells, which the body produces to fight infection. Bacteria also can be found in the urine of healthy people, so a bladder infection is diagnosed based both on your symptoms and lab tests.

Urine culture. In some cases, a health care professional may culture your urine to find out what type of bacteria is causing the infection. Urine culture is not required in every case, but is important in certain circumstances, such as having repeated UTIs or certain medical conditions. The results of a urine culture take about 2 days to return and will help your health care professional determine the best treatment for you.

Imaging and other tests

If you have repeated bladder infections or have a complicated infection, a doctor may order imaging tests to look at your urinary tract. A complicated UTI is an infection linked to certain other conditions, such as a kidney stone, or a structural problem in your urinary tract. Read more about imaging tests for your urinary tract.

Doctors may use cystoscopy to look inside the urethra and bladder. Doctors use a cystoscope, a tube-like instrument, during cystoscopy to look for swelling, redness, and other signs of infection in addition to structural problems that may be causing the infection.

Doctors may also use urodynamic testing, which is any procedure that shows how well your bladder, sphincters, and urethra are storing and releasing urine.


How do health care professionals treat a bladder infection?

If you have a bladder infection caused by bacteria, a health care professional is likely to prescribe antibiotics. If the diagnosis is not certain, based on your symptoms or lab test results, you may not need antibiotics. Instead, your health care professional will work to find the cause and the best treatment for your symptoms.


Which antibiotic you take is based on the type of bacteria causing your infection and any allergies you may have to antibiotics.

The length of treatment depends on

  • how severe the infection is
  • whether your symptoms and infection go away
  • whether you have repeated infections
  • whether you have problems with your urinary tract

Men may need to take antibiotics longer because bacteria can move into the prostate gland, which surrounds the urethra. Bacteria can hide deep inside prostate tissue.

Follow your health care professional’s instructions carefully and completely when taking antibiotics. Although you may feel relief from your symptoms, make sure to take the entire antibiotic treatment.

If needed, a health care professional may prescribe other medicines to relieve any pain or discomfort from your bladder infection.

At-home treatments

Drink a lot of liquids and urinate often to speed healing. Water is best. Talk with a health care professional if you can’t drink a lot of liquids due to other health problems, such as urinary incontinence, urinary frequency, or heart or kidney failure.

A heating pad on your back or abdomen may help you manage pain from a kidney or bladder infection.


Researchers are studying ways to treat or prevent bladder infections without taking antibiotics. The bacteria that cause these infections can become stronger and harder to fight when a person takes antibiotics repeatedly. Alternate approaches include probiotics, vaginal estrogen, and "watchful waiting." Talk to your health care professional about any treatment for a bladder infection before you start it, including home remedies and supplements. Some supplements can have side effects or react poorly with other medications you take.

Man drinks from a large glass of water as he works on a computer.
Drink lots of liquids and urinate often to speed healing. Water is best.

How can I prevent a bladder infection?

Changing some of your daily habits and lifestyle choices may help you prevent repeated bladder infections.

Drink enough liquids

Most people should try drinking six to eight, 8-ounce glasses of liquid a day. Talk with a health care professional if you can’t drink this amount due to other health problems, such as urinary incontinence, urinary frequency, or heart or kidney failure.

Be aware of your bathroom habits

Take enough time to fully empty your bladder when urinating—don’t rush it. Urinate after sex to flush away bacteria that may have entered the urethra during sex. Clean the genital area before and after sex.

If you’re a woman, wipe from front to back, especially after a bowel movement, to keep bacteria from getting into the urethra.

Wear loose-fitting clothing

Consider wearing cotton underwear and loose-fitting clothes so air can keep the area around the urethra dry.

Consider switching birth control methods if you have repeat bladder infections

If you have trouble with repeat bladder infections, talk with a health care professional about your birth control. Consider switching to a new form of birth control if you use diaphragms, unlubricated condoms, or spermicide, all of which can increase your chances of developing a bladder infection. Consider using lubricated condoms without spermicide or using a nonspermicidal lubricant.

Eating, Diet, & Nutrition

Can my eating, diet, and nutrition help prevent bladder infections?

Experts don’t think eating, diet, and nutrition play a role in preventing or treating bladder infections. Although some research shows that cranberry juice, extract, or pills may help prevent these infections, not enough evidence shows this. Research shows that cranberry products are not effective in treating a bladder infection if you already have one.2

Can drinking liquid help prevent or relieve bladder infections?

Yes. Drink six to eight, 8-ounce glasses of liquid a day. Talk with a health care professional if you can’t drink this amount due to other health problems, such as urinary incontinence, urinary frequency, or kidney failure. The amount of liquid you need to drink depends on the weather and your activity level. If you live, work, or exercise in hot weather, you may need more liquid to replace the fluid you lose through sweat.


Clinical Trials

The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) and other components of the National Institutes of Health (NIH) conduct and support research into many diseases and conditions.

What are clinical trials, and are they right for you?

Clinical trials are part of clinical research and at the heart of all medical advances. Clinical trials look at new ways to prevent, detect, or treat disease. Researchers also use clinical trials to look at other aspects of care, such as improving the quality of life for people with chronic illnesses. Find out if clinical trials are right for you.

Watch a video of NIDDK Director Dr. Griffin P. Rodgers explaining the importance of participating in clinical trials.

What clinical trials are open?

Clinical trials that are currently open and are recruiting can be viewed at

Last Reviewed March 2017
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This content is provided as a service of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), part of the National Institutes of Health. NIDDK translates and disseminates research findings to increase knowledge and understanding about health and disease among patients, health professionals, and the public. Content produced by NIDDK is carefully reviewed by NIDDK scientists and other experts.

The NIDDK would like to thank:
Ann E. Stapleton, MD, FIDSA, FACP, University of Washington School of Medicine