UTI (urinary tract infection)

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A UTI is an infection in any part of your urinary system — your kidneys, ureters, bladder and urethra. Most infections involve the lower urinary tract the bladder and the urethra.

UTIs typically occur when bacteria enter the urinary tract through the urethra and begin to multiply in the bladder. Although the urinary system is designed to keep out such microscopic invaders, these defenses sometimes fail.

UTIs mainly occur in women and affect the bladder and urethra.

  • Bladder infection (cystitis). It’s usually caused by Escherichia coli (E. coli), a bacteria commonly found in the gastrointestinal tract. Sexual intercourse may lead to cystitis, but you don’t have to be sexually active to develop it. Women are at particular risk of a bladder infection because of the short distance from the urethra to the anus and the urethral opening to the bladder.
  • Urethral infection (urethritis). A urethral infection may occur when gastrointestinal bacteria spread from the anus to the urethra. Because the female urethra is close to the vagina, sexually transmitted infections, such as herpes, gonorrhea and chlamydia, also can cause urethritis.


UTIs don’t always cause signs and symptoms. When they do, signs and symptoms may include:

  • A strong, persistent urge to urinate
  • A burning sensation when urinating
  • Passing frequent, small amounts of urine
  • Urine that appears cloudy
  • Urine that appears red, bright pink or cola-colored — a sign of blood in the urine
  • Strong-smelling urine
  • Pelvic pain, in women
  • Rectal pain, in men

Being female and being sexually active increases your risk of a urinary tract infection. Women who use diaphragms for birth control also may be at higher risk, as may women who use spermicidal agents. After menopause, UTIs can become more common because reduced estrogen causes changes in the urinary tract, making it more vulnerable to infection. People who need to use a catheter to urinate also are at increased risk of UTIs.


Antibiotics are generally used to treat urinary tract infections. Which drugs are prescribed and for how long you’ll need to take them will depend on your health and the type of bacterium involved.

Usually, symptoms clear up within a few days of treatment. For an uncomplicated UTI, your doctor may recommend a shorter course of treatment, such as taking an antibiotic for one to three days. In other cases, you may need to take antibiotics for a week or more.

If you experience frequent urinary tract infections, your doctor may recommend a longer course of antibiotics. If your infections are related to sexual activity, another option may be to take a single dose of an antibiotic after sexual intercourse. If you’re postmenopausal, your doctor may prescribe vaginal estrogen therapy to help reduce the chance of recurrent UTIs.


There’s some indication, though unproven, that cranberry juice may have infection-fighting properties, and drinking it daily may help prevent UTIs.

It’s not clear how much cranberry juice you need to drink or how often you need to drink it to have an effect. If you like cranberry juice and you feel it helps prevent UTIs, there’s little harm in drinking it. But don’t drink cranberry juice if you’re taking the blood-thinning medication warfarin because it may increase the risk of bleeding.

Other tips to reduce UTIs include:

  • Drink plenty of water. It dilutes your urine and helps flush out bacteria before infection can begin.
  • Wipe from front to back. Doing so after urinating or a bowel movement helps prevent bacteria in the anal region from spreading to the vagina and urethra.
  • Empty your bladder soon after intercourse. This helps to flush out bacteria.
  • Avoid irritating feminine products. The use of deodorant sprays, douches and powders in the genital area can irritate the urethra.


Left untreated, a urinary tract infection can lead to a kidney infection. Acute or chronic kidney infections can result in permanent kidney damage, especially in young children, or the bacteria can spread to your bloodstream. Signs and symptoms of a kidney infection include:

  • Upper back and side (flank) pain
  • High fever
  • Shaking and chills
  • Nausea
  • Vomiting

Treatment usually includes antibiotics. You may need to be hospitalized.

Track important kidney function parameters.

Excerpt From: The Mayo Clinic. “Mayo Clinic A to Z Health Guide”.

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