Causes and Risk Factors for Urinary Tract Infections (UTIs)

What Are Bladder Infection Risk Factors?

Urinary tract infections (UTIs) are infections of the urinary system, which includes the urethra, bladder, ureters, and kidneys. Most UTIs begin when bacteria—often from the bowel—enter through the urethra and multiply in the bladder. A bladder infection may spread to one or both kidneys if it is not treated. Understanding common bladder infection risk factors may help people take steps that lower their risk, although not all UTIs are preventable.

The most common cause of bladder infection is Escherichia coli (esh-uh-RIK-ee-uh KOH-lye), a bacterium commonly found in the intestines. Other bacteria can also cause UTIs, particularly in people with urinary catheters, urinary tract abnormalities, recent healthcare exposure, or weakened immune systems. Rarely, fungi can cause a UTI. An infection usually starts when germs enter the urethra and move up into the bladder. If the infection reaches the kidneys, it becomes more serious.

Less commonly, infection can reach the kidneys through the bloodstream, usually in the setting of another infection or serious illness. Doctors usually treat bladder infections with antibiotics. But symptoms alone can't always confirm you have a UTI. Taking antibiotics you don't need can cause side effects and make future infections harder to treat. Learn more about medication options to treat urinary tract infections (UTIs).

Bladder Infection Risk Factors You Can't Change

Non-modifiable risk factors are factors a person cannot change. Some overlap with medical conditions that can be treated or managed. Important risk factors include:

• Sex assigned at birth and anatomy: UTIs are more common in women. This is because the urethra is shorter and sits closer to the anus. That makes it easier for bacteria to reach the bladder. UTIs can also occur in males; in men, a UTI may be associated with prostate enlargement or another urinary tract problem.
• Age and menopause: Risk rises with age in both sexes. After menopause, lower estrogen levels and changes in vaginal and urinary tissues can increase the likelihood of recurrent UTIs.
• Pregnancy: Pregnancy changes the urinary tract and increases the chance that a UTI will progress to a kidney infection. Urinary symptoms during pregnancy should be assessed promptly.
• History and genetics: A previous UTI is one of the strongest predictors of another UTI. A family history may also be associated with susceptibility, although genetics is only one of many possible contributors.

Having one or more risk factors does not mean a person will develop a UTI. Individual risk also depends on urinary tract function, health conditions, medications, procedures, and prior infections.

Bladder Infection Risk Factors You May Be Able to Change

Some UTI risk factors can be reduced or medically managed, although they may not be fully under a person's control. These include:

• Difficulty emptying the bladder or blocked urine flow: Some conditions make it harder to fully empty the bladder, which lets bacteria stay and grow. These include:
  • Urinary retention (trouble emptying the bladder)
  • Kidney stones
  • An enlarged prostate
  • Nerve problems affecting the bladder
  • Certain structural problems in the urinary tract

Incontinence itself does not necessarily cause a UTI, but associated bladder-emptying problems may increase risk.

• Diabetes or a weakened immune system: Diabetes can raise your UTI risk, especially if your blood sugar isn't well controlled. Conditions or medicines that weaken your immune system can also raise your risk — and the risk of complications.
• Urinary catheters and procedures: An indwelling urinary catheter is a major risk factor, and the risk increases the longer it remains in place. Catheters should be used only when needed and removed as soon as clinically appropriate.
• Sexual activity and certain contraceptives: Sexual activity can increase UTI risk, especially in people prone to recurrent bladder infections. Spermicides and diaphragms are also associated with higher risk; a healthcare professional can discuss alternatives when relevant. UTIs are not generally considered sexually transmitted infections.
• Not drinking enough fluid: Low fluid intake may contribute to recurrent UTIs in some people. Increasing water intake may help people who usually drink less than about 1.5 liters (50 ounces) a day, unless a healthcare professional has advised fluid restriction.

Addressing these factors may reduce risk. Recurrent UTIs, UTIs in males, and infections linked to urinary retention, stones, catheters, pregnancy, or immune suppression may require additional evaluation.

Reducing Bladder Infection Risk Factors

No prevention method eliminates UTI risk, and some commonly repeated tips have limited evidence. The following measures may help, particularly for people with recurrent infections. Ask a healthcare professional which approaches are appropriate for you.

• Drink enough fluid: Water is a good choice. There is no single amount that is right for everyone. People with heart failure, kidney disease, or another reason to limit fluids should follow their healthcare professional's advice.
• Do not routinely delay urination: Empty the bladder when needed. If you have trouble emptying your bladder completely, discuss it with a healthcare professional.
• Use gentle hygiene: Wipe from front to back after a bowel movement and avoid harsh or fragranced products that cause irritation. Excessive washing or douching does not prevent UTIs and may irritate genital tissues.
• Urinate after sexual activity: This is a low-risk step some people find helpful, although evidence that it prevents UTIs is limited. Avoid spermicides if they appear to trigger recurrent infections, and discuss contraceptive alternatives if needed.
• Review catheter need and care: If you have a urinary catheter, ask whether it is still needed and follow instructions for hand hygiene, tubing care, and keeping the drainage bag below bladder level.
• Discuss prevention for recurrent UTIs: Cranberry products may reduce recurrences in some women, but products and doses vary and they do not treat an active infection. For peri- or postmenopausal women with recurrent UTIs, vaginal estrogen may be recommended when appropriate. Other preventive medicines require clinician guidance.

Get medical care if you have any of these:

• Burning when you urinate
• Needing to urinate often or urgently
• Discomfort in your lower belly
• Cloudy, bloody, or strong-smelling urine

Seek prompt care for fever or chills, nausea or vomiting, or pain in the back, side, or groin, which may signal a kidney infection. Prompt assessment is also important during pregnancy and for children, males, people with catheters, weakened immune systems, or significant urinary tract problems.

A healthcare provider can check if a UTI is causing your symptoms. They can decide if you need testing. They can also recommend treatment or ways to prevent future infections, based on your health history.