Bladder Infection (Cystitis)

Medically Reviewed on 5/27/2022

What is a bladder infection (cystitis)?

Cystitis is inflammation of the bladder. Most cystitis is from bacterial infections involving the bladder and less commonly may be due to other infectious diseases, including yeast infections, viral infections, or the result of other causes such as chemical irritants of the bladder, or for unknown reasons (interstitial cystitis).

Bladder infection (infectious cystitis) is a type of urinary tract infection (UTI). Other forms of urinary tract infection include

This review will specifically address infectious cystitis.

The urine in the bladder is normally free of bacteria (sterile). However, bacteria may be present in the bladder but not cause inflammation or symptoms of an infection.

  • This is asymptomatic bacteriuria, not cystitis.
  • Asymptomatic bacteriuria is bacteria in the urine that does not cause symptoms.
  • It is important to differentiate asymptomatic bacteriuria from cystitis, to prevent overuse of antibiotics.
  • Most people with asymptomatic bacteriuria do not require antibiotics.
  • In fact, the guidelines for the Infectious Disease Society of America recommend only treating asymptomatic bacteriuria in pregnant women or immediately before urologic procedures.

Cystitis can be complicated or uncomplicated. Uncomplicated cystitis is a bladder infection in a healthy person with a structurally and functionally normal urinary tract. A complicated bladder infection is one that occurs in association with factors that increase the chance of developing a bacterial infection and decrease the chance of antibiotic therapy being effective. Such abnormalities include obstruction from stones, congenital blockages, urethral strictures, and prostate enlargement.

What is the bladder?

Bladder infection
Antibiotic treatment can resolve a bladder infection or UTI quickly.

The bladder is a hollow muscular organ that is located in the pelvis. The bladder has two functions: one is to store urine and the other is to release/expel urine. Urine drains from the kidneys (one on each side of the body), down the ureters (one on each side of the body), and into the bladder. The urine is stored in the bladder where it remains until urination. When it is time to urinate, the bladder muscle contracts and the outlet of the bladder and sphincter muscles relax to allow urine to pass through the urethra to leave the body. The bladder and urethra are part of the lower urinary tract, whereas the kidneys and ureters are part of the upper urinary tract.

What are some risk factors for bladder infection?

It is important to modify risk factors, when possible, to decrease the risk of recurrent urinary tract infections.

The female gender is one of the main risk factors for bladder infection. Women are at increased risk for bladder infections for a number of reasons including the following:

  • Women have a shorter urethra than men which allows bacteria to gain access to the bladder much easier than in men.
  • Sexual activity can increase the risk of urinary tract infections. Sexually active women tend to have more urinary tract infections than women who are not sexually active.
  • The type of birth control a woman uses can affect the risk of developing urinary tract infections. Women who use diaphragms for birth control may have a higher risk of urinary tract infections, as well as women who use spermicidal agents.
  • Menopausal women are at greater risk of developing urinary tract infections. Decreased estrogen levels cause changes in the urinary tract, making it more susceptible to bacteria.

Bacteria in the bladder is one of the most common infectious issues that occur in pregnancy. The risk of having bacteria in the urine increases with lower socioeconomic status, history of multiple children, and sickle cell trait. Pregnant women are less likely to clear the bacteria in the bladder compared to nonpregnant women and are more likely to develop symptoms. In addition, pregnant women have a higher risk of a bladder infection progressing to a kidney infection (pyelonephritis).

Other risk factors include the following:

  • Urinary tract abnormalities such as obstruction to the flow of urine at any level, vesicoureteral reflux (a structural abnormality that allows urine to go backward from the bladder to the kidneys), and neurologic conditions that affect bladder function
  • In men with prostate enlargement, a bladder infection is also more common than in the general male population. Prostate enlargement can lead to obstruction of the normal flow of urine out of the bladder and into the urethra. Residual urine can then become infected. The higher bladder pressure needed to push urine past the enlarged prostate causes decreased blood flow to the bladder, making it more susceptible to bacteria.
  • Urinary catheters (Foley catheters) are another potential risk for bladder infection. People typically use these urinary catheters in settings where an individual may not be able to urinate naturally. Urinary catheters simply provide a physical vehicle to transport bacteria from outside directly into the bladder and the urinary system. Foley catheters are commonly used in patients with severe illness, limited mobility, urinary incontinence (inability to hold their urine), bladder obstruction and urinary retention (prostate enlargement, urethral scarring, prostate cancer), bladder trauma, bladder cancer, bladder dysfunction due to neurologic conditions, or who are unable to get out of bed.
  • Bladder infection is more commonly seen in patients with neurologic conditions that may affect bladder function, such as multiple sclerosis (MS), stroke, and other diseases of the nervous system, than in the public. In these and other similar neurologic diseases, bladder function may be impaired due to abnormal nervous system control of the bladder (neurogenic bladder). As a result, a person may retain urine in the bladder after voiding. Urinary retention can be a cause of bladder infection. Furthermore, if urinary retention becomes more serious, causing pain and kidney dysfunction, Foley catheters may become necessary to empty the bladder and relieve the bladder pressure caused by excessive retention of urine. A catheter, in turn, can substantially increase the risk of bladder infection.
  • In addition to the Foley catheter, any instrumentation of the urinary tract or nearby structures can potentially lead to cystitis. Medical procedures (cystoscopy, bladder biopsy, prostate procedures), vaginal pessary, and IUD (intrauterine device) placement for birth control can pose an increased risk of developing a bladder infection.
  • In children and toddlers, the risk for bladder infection may be higher in females, uncircumcised males, those with structural abnormalities of the urinary tract, and Caucasians (four times higher than in African Americans).
  • Elderly people are also at higher risk of suffering bladder infections as are individuals who take medications that weaken the immune defense system.
  • Constipation

What causes bladder infections?

Bladder Infections
In women, the bacteria from the stool travel first to the vagina and then enter the urethra.

All urinary tract infections are the result of interactions between the infecting organism (bacteria, yeast, virus), the number of organisms that are present in the bladder, and the body’s ability to fight off the organism (host defense mechanisms).

The most common way bacteria gain access to the urinary system from the outside is through the urethra (the tube that allows urine to pass from the bladder to the outside of the body).

  • The most common source of bacteria that cause UTIs is stool.
  • In women, the bacteria from the stool travel first to the vagina and then enter the urethra.
  • Sometimes bacteria may enter the bladder via the urethra from nearby skin.
  • In general, women are more susceptible to bladder infections due to the shorter length of the urethra.
  • In the first year of life, boys have a higher risk of UTIs, but thereafter girls have a higher risk that persists in adulthood.
  • Increasing age is a risk factor for UTIs.

In terms of specific bacteria, E. coli (Escherichia coli) is by far the most common organism responsible for bladder infection or cystitis. Staphylococcal (staph) organisms (from skin) and other gut bacteria (Proteus, Klebsiella, Enterococcus) are other bacteria that can cause cystitis and other forms of urinary infections. The type of organism causing the infection can vary with the individual’s age. For example, Staphylococcus saprophyticus, a skin bacteria, causes approximately 10% of symptomatic bladder infections in young sexually active women, whereas it rarely causes bladder infections in males and elderly individuals.

Rarely, fungi can cause bladder infections. Candida is the most common fungus to cause a bladder infection. Candida infections of the bladder and urinary tract are much less common than bacterial infections. Bladder infections from Candida can occur in patients whose immune system is weakened, individuals who have been treated with powerful antibiotics for other infections, and individuals who have had indwelling urinary catheters.

Viruses can rarely cause bladder infections. Viral cystitis can occur in individuals after bone marrow transplantation and in other individuals with a weakened immune system (immunocompromised individuals). Adenovirus can cause bladder infections and the BK virus is another virus that can cause bladder infections in individuals who have undergone bone marrow transplantation.


Bladder Infection (Cystitis) See a medical illustration of the female bladder anatomy along with our entire medical gallery of human anatomy and physiology See Images

What are the symptoms of a bladder infection?

Because cystitis is more common in women, most signs and symptoms listed below pertain to cystitis in women unless otherwise indicated.

General symptoms of a bladder infection may include the following:

  • Dysuria (painful urination)
  • Urinary frequency
  • Urinary urgency (sudden, compelling urge to urinate)
  • Hesitancy to void urine
  • Bladder pain (pain in the lower abdomen around the pubic bone and pelvic area)
  • Incomplete voiding of urine (leaving urine in the bladder after urinating)
  • Urinary incontinence (involuntary loss of urine), which may be associated with urgency

Fevers, chills, nausea, vomiting, and poor oral intake rarely occur with a bladder infection, although they are more common upper urinary tract infections, such as pyelonephritis (kidney infection).

Some common signs of bladder infection are

  • lower abdominal tenderness;
  • blood in urine (hematuria);
  • less commonly, tenderness on the sides of the back (flanks);
  • foul-smelling urine; and
  • in elderly patients, lethargy or confusion may be the only signs.

How are bladder infections diagnosed?

A urinalysis (UA) is the initial evaluation for a bladder infection. In most cases, health care professionals use a voided urine specimen, however, there is a risk of contamination by skin bacteria. A "clean-catch" voided urine specimen involves voiding and collecting a urine sample "mid-stream" as opposed to at the very start or end of voiding. A catheterized urine sample is more accurate but has the risk of introducing bacteria into the bladder and may be uncomfortable in children. In infants, medical professionals can perform a suprapubic aspiration.

If the source of the infection is unclear, three separate urine samples may be collected: the first void (the first 10 ml of urination) reflects whether or not bacteria are in the urethra, and the second sample is a midstream void (that which occurs after the first 10 ml) and reflects whether bacteria are in the bladder. If there is a concern for bacteria in the prostate, a medical professional performs a rectal examination and massages the prostate to express fluid from the prostate into the urethra, and the third urine sample is obtained after the prostate massage. The voided urine should be collected midstream.

A quick office-based urinalysis, called a urine dipstick, is unable to detect if bacteria are present. However, health care professionals use it to detect the presence of nitrite in the urine and leukocyte esterase. Nitrite is a chemical that forms when bacteria in the urine break down a chemical called nitrate, which is normally present in the urine. The nitrite test is not positive for all bacterial infections of the bladder, as not all bacteria can break down nitrate to nitrite. Besides, the urine dipstick is unable to determine the number of white blood cells (infection cells) present in the urine but assesses whether or not white blood cells are present by measuring leukocyte esterase activity. Leukocyte esterase is a chemical produced by white blood cells. The presence of both nitrites and an elevated leukocyte esterase are very suggestive of a urinary tract infection.

A formal urinalysis with an examination of the urine under the microscope can identify whether or not bacteria are present in the urine as well as determine the number of white blood cells present in the urine. Examination of the urine under the microscope can also determine if yeast is present in the urine. Viruses cannot be seen under the routine microscope and require special tests to identify.

The definitive test to determine if there is a bladder infection is the urine culture. The urine culture identifies the number and type of bacteria in the urine as well as determines the sensitivity of the bacteria to several different antibiotics. The usual cutoff for a urinary tract infection is the presence of greater than 100,000 bacteria, however, in the presence of symptoms, a positive leukocyte esterase or > 10 white blood cells on urinalysis, even fewer bacteria in the urine is supportive of a urinary tract infection.

A recent publication in the Infectious Disease Clinics of North America highlights the importance of differentiating between asymptomatic bacteriuria, and possible, probable, and definite urinary tract infection. Localizing symptoms and signs (pain with urination, urinary frequency, suprapubic/bladder pain, bloody urine, pain in the flank, new or worsening urgency or urinary incontinence), pyuria (white blood cells in the urine), or positive leukocyte esterase on urinalysis are the most important predictors of a urinary tract infection. They note that the diagnosis of a urinary tract infection requires three components:

  • clinical symptoms of infection localized to the urinary tract or nonspecific symptoms of infection (fever, chills, change in mental status) in the absence of symptoms suggesting infection in another part of the body,
  • the presence of white blood cells in the urine and bacteria in the urine, and
  • absence of another infection or noninfectious process accounting for the symptoms and signs.

If symptoms of an upper urinary tract infection (pyelonephritis), fever, flank pain, nausea, or vomiting are present, health care professionals will obtain a blood test (a complete blood cell count [CBC]). If there is a concern for a severe infection, medical professionals will culture a sample of blood to see if there are bacteria in the bloodstream. Radiologic studies are not routinely obtained in the case of cystitis, however, if there are signs of a kidney infection (pyelonephritis) such as flank pain, fevers/chills, or there is a failure to respond to antibiotics (with persistent or worsening symptoms), then radiologic testing (renal ultrasound, CT scan, or MRI) can be performed to rule out an abscess or other abnormalities.

If a physician suspects constipation, a plain X-ray of the abdomen may be obtained to assess the severity of constipation.

What are treatment options for a bladder infection?

The appropriate use of antibiotics can treat and cure a bladder infection. The selection and duration of antibiotic treatment depend on the severity of the infection, previous history of similar infection, and patient factors (age, gender, allergies, other medications, and other medical problems).

The antibiotic initially chosen will be dependent on these factors as well as urine culture results from prior infections. Sometimes a doctor will change the prescribed antibiotic if the urine culture results show that the bacteria is resistant to the antibiotic used initially. In most bladder infections, oral (by mouth) antibiotics are used. The length of treatment will vary with whether or not the infection is complicated or not, as well as other risk factors. Sometimes intravenous antibiotics may be needed until a suitable oral antibiotic has been identified.

A number of different types of antibiotics treat bladder infections, including

Doctors commonly prescribe the antibiotics nitrofurantoin and trimethoprim-sulfamethoxazole for uncomplicated cystitis. However, with the increasing emergence of resistant organisms, physicians prescribe fosfomycin more frequently for uncomplicated cystitis.

Resistance to various antibiotics varies in different areas of the country, and this may also affect the antibiotic that your physician chooses initially until the culture results are available.

It is important that you tell your physician all the medications, including any over-the-counter medications so that the physician can ensure that the selected antibiotic will not interfere with your current medications. Your physician and/or pharmacist can also review more commonly encountered side effects of the prescribed antibiotic. It often takes up to 72 hours, sometimes longer, to have the final culture result and antibiotic sensitivities available.

Self-medication for bladder infection is occasionally an option in patients with mild, recurrent infections. In reliable and compliant individuals who are familiar with the symptoms of frequent bladder infections, their treating physicians can prescribe appropriate bladder infection antibiotics to them in advance. The patient may then start bladder infection medication on their own at the onset of their symptoms. If the symptoms do not improve after several days of treatment, a health care professional will obtain a urine culture from the patient to ensure the use of the proper antibiotic.

Bladder muscle spasm and bladder inflammation are responsible for some of the symptoms associated with a bladder infection, such as bladder pain, urinary frequency, urgency, and dysuria.

  • Phenazopyridine is a medication often used to treat symptoms of painful urination due to bladder infection.
  • Other similar medications are available over the counter.
  • It is important to read the prescribing information on these medications (for example, physicians only recommend the use of pyridium for two days use when used with an antibiotic for a UTI).

Physicians sometimes recommend prophylactic antibiotics (a low dose of antibiotic on a daily basis) for individuals who develop frequent symptomatic UTIs. Similarly, women who develop UTIs related to sexual activity may take a single dose of antibiotic around the time of intercourse.

Your provider may ask you to have a follow-up urine culture to ensure adequate treatment of your UTI. In addition, if your urine culture shows bacteria associated with the development of stones, a health care professional may obtain an ultrasound of the kidneys or a plain abdominal X-ray to see if you have a kidney stone.

Are home remedies effective for a bladder infection?

People have used cranberry products to prevent bladder infections. Cranberries contain a substance that can prevent bacteria from sticking on the walls of the bladder. A Cochrane Database systematic review of cranberries for preventing UTIs in 2012 concluded that the evidence for cranberry products, particularly cranberry juice, over the long term is small and that cranberry juice could not be recommended at that time for the prevention of UTIs. Further studies need to evaluate other cranberry preparations.

Probiotics are preparations that contain live bacteria, for example, lactobacillus, that can prevent other bacteria from growing and moving up from the bladder to the kidney. The probiotic decreases the ability of the infecting bacteria from sticking to the bladder and growing and may also affect the ability of the individual's own body to fight off bacteria. A Cochrane Database review in 2015 demonstrated no significant difference in the risks of recurrent UTIs for probiotics compared with placebo (a substance that has no therapeutic effect, used as a control in testing a new medication) or antibiotic prophylaxis in either women or children, however, there were a limited number of good-quality studies.

Adhering to the prescribed antibiotic regimen and staying well hydrated are essential components of home remedies for bladder infection.

What is the treatment for a bladder infection during pregnancy

In pregnant women, bladder infection can be complicated. Sometimes the presence of bacteria without obvious signs of infection in pregnant patients could be harmful and may lead to severe infections that compromise the pregnancy. As previously stated, the presence of asymptomatic bacteria in a pregnant woman warrants treatment. The choice of antibiotics during pregnancy may be different for bladder infection during pregnancy due to potential harm to the fetus and thus, careful evaluation by a physician is very important to start the correct therapy promptly.

Subscribe to MedicineNet's Women's Health Newsletter

By clicking "Submit," I agree to the MedicineNet Terms and Conditions and Privacy Policy. I also agree to receive emails from MedicineNet and I understand that I may opt out of MedicineNet subscriptions at any time.

What are potential complications of a bladder infection?

Complications of a bladder infection can occur without appropriate diagnosis or treatment. An untreated or poorly treated bladder infection can ascend the urinary system and lead to kidney infection (pyelonephritis) and enter the bloodstream, leading to sepsis (an infection spread into the blood), which can be life-threatening. In children, particularly, kidney infections can cause permanent damage to the kidney. In pregnant women, complications of bladder infections include an increased risk of delivering low birth weight or premature infants. Urethral narrowing (stricture) in men from recurrent urethral infections can occur, more commonly with sexually transmitted diseases such as gonorrhea.

Is it possible to prevent bladder infections?

Although the use of cranberry products (whole cranberries, cranberry juice, cranberry pills) is thought to help prevent infections, more recent evidence fails to demonstrate sufficient effectiveness in preventing UTIs. The role of probiotics in the prevention of urinary tract infections is unclear.

Regular voiding and bowel habits may help decrease the risk of bladder infections. Timely and effective bladder emptying as well as avoiding constipation may decrease the number of bacteria present near the urethra and decrease the likelihood of bacteria growing in the bladder.

Strict adherence to guidelines to prevent catheter associated urinary tract infections is helpful in reducing bladder infections. The Center for Disease Control and Prevention has developed guidelines with respect to appropriate urinary catheter use, proper techniques for insertion, and maintenance of urinary catheters ( Individuals who perform clean intermittent catheterization (insertion of a catheter to drain the bladder and removal several times a day) and who develop frequent infections may change to single-use systems.

Sexual intercourse is another potential risk factor for bladder infection. Thus, it may be advisable to empty the bladder (urinate) after sexual activity, draining bacteria that could have entered the bladder. Available clinical data does not completely support this, and some experts do not recommend this. The use of prophylactic antibiotics at the time of intercourse may also be helpful in individuals with recurrent UTIs related to sexual activity.

Preventive use of antibiotics may also have a role in preventing bladder infections. In some female patients with frequent bladder infections (more than three to four times per year) or with symptoms of bladder infection present after sexual intercourse, a short course of antibiotics can be taken as a preventive measure. The treating doctor needs to recommend this method, and the strategy needs to be outlined for patients who are deemed reliable.

Physicians also sometimes recommend preventive antibiotics in patients undergoing invasive urologic procedures (cystoscopy, prostate biopsy, bladder biopsy). Occasionally, medical professionals may order a urinalysis and/or urine culture before the procedure and if an infection is suggested, then antibiotics are prescribed to prevent an infection after the procedure.

What is the prognosis for a bladder infection?

The overall prognosis for a bladder infection is very good. An uncomplicated bladder infection typically does not cause any damage to the bladder. Identification of risk factors may help decrease the risk of recurrent infections.


Urinary Tract Infection (UTI) Symptoms, Diagnosis, Medication See Slideshow
Medically Reviewed on 5/27/2022
Brusch, John L., et al. "Cystitis in Females." Medscape. Feb. 25, 2013.

Cayley, Jr., William E. "Are Cranberry Products Effective for the Prevention of Urinary Tract Infections?" Am Fam Physician 88.11 Dec. 1, 2013: 745-746.

Colgan, Richard, and Mozella Williams. "Diagnosis and Treatment of Acute Uncomplicated Cystitis." Am Fam Physician 84.7 Oct. 1, 2011: 771-776.

Corles-Penfield, N.W., B.W. Trautner, and R. Jump. "Urinary tract infection and asymptomatic bacteriuria in older adults." Infectious Disease Clinics of North America 31.4 Dec. 2017: 672-688.

Gupta, K., T.M. Hooton, K.G. Naber, et al. "Guidelines for Antimicrobial treatment of acute uncomplicated cystitis and pyelonephritis in women." Clinical Infectious Diseases 52 (2011): e103-e120.

Schwenger, E.M., A.M. Tejani, and P.S. Loewen. "Probiotics for preventing urinary tract infections in adults and children." Cochrane Systematic review-Intervention 23 December 2015. <>.

Trestioreanu, A.Z., A. Lador, M.T. Sauerbrun-Cutler, and L. Leibovici. "Antibiotics for asymptomatic bacteriuria (Review)." Cochrane Database of Systematic Reviews Issue 4 (2015). <https://www.cochrane>.