UTI Causes, Risk Factors, and Prevention

UTI Causes and Risk Factors

Urinary tract infections occur when harmful bacteria enter the urethra — the tube that carries urine out of the body. Risk factors for UTIs may differ for men, women, and children.
UTI Causes and Risk Factors
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Updated on October 14, 2024
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Urinary tract infections (UTIs) are infections in the urinary system, which consists of the urethra, bladder, kidneys, and ureters.

UTIs typically occur when bacteria enter the bladder or urethra, which is the tube that carries urine out of the body. Left untreated, a UTI can spread to the rest of the urinary tract.

UTI causes and risk factors differ among women, men, and children, but there are some factors that are shared between all people. Preventive steps can also be taken to avoid UTIs.

What Causes UTIs?

More than 90 percent of UTIs are caused by E. coli, a type of bacteria that normally lives in your intestines. But, other types of bacteria may cause UTIs, too.

UTI Causes in Females

Common UTI causes in females include:

  • Wiping the Wrong Way Wiping from back to front can introduce bacteria from the anus into the urinary tract.
  • Poor Genital Hygiene Not washing your genital area before or after sex can allow bacteria to travel from the urethra to the rest of the urinary tract. In addition, not washing your hands before sex or masturbation can introduce bacteria to the genital area.

  • Using Spermicides or a Diaphragm These forms of birth control can make it easier for harmful bacteria to enter the urinary tract. Spermicides may kill off good bacteria in and around the vagina, making it easier for harmful bacteria to thrive. Diaphragms can prevent you from completely emptying your bladder, which can promote harmful bacteria.
  • Wearing Tiny Lingerie Research differs regarding the possibility that wearing a thong can cause a UTI. “The Thong Study” published in 2009 found that wearing a thong resulted in an increased risk of reporting a UTI.

     However, the “B-Thong” study published in 2019 concluded that wearing a thong was not associated with any urogenital infections (infections of the urinary system or reproductive organs).

Sometimes, certain changes in your body can cause UTIs:

  • Pregnancy Pregnancy leads to changes in the urinary tract, which can make it harder to fully empty your bladder. Pregnancy can also suppress the immune system, making you more susceptible to infection.

  • Menopause Menopause decreases estrogen levels. This can result in vaginal dryness, which increases the chance of getting a UTI.

UTI Causes in Males

Common UTI causes in males include:

  • Enlarged Prostate An enlarged prostate, also known as benign prostatic hyperplasia (BPH), can make it harder to fully empty the bladder. An enlarged prostate may also block the flow of urine out of the bladder.
  • Unprotected Anal Sex The harmful bacteria that cause UTIs can be found in and around the anus. Without protection, this bacteria can enter the urethra.

UTI Causes in Children

Common UTI causes in infants and children include:

  • Prematurity UTIs are common in premature infants because their immune systems aren’t fully developed.

     This makes it harder to fight off infections.
  • Being Uncircumcised Uncircumcised boys have a higher chance of getting a UTI than circumcised boys.

  • Poor Bathroom Hygiene In girls, wiping back to front can increase the chance of bacteria from the anus entering the urinary tract.

  • Urinary Tract Abnormalities About 20 to 30 percent of infants and toddlers with a UTI have a condition called vesicoureteral reflux (VUR). This condition causes urine to flow backward from the bladder to the ureters, which are the tubes that carry urine from the kidneys to the bladder.

  • Sitting in a Wet Swimming Suit Warm, moist areas can be a breeding ground for bacteria.

Risk Factors

Certain factors can increase the risk of developing a UTI, which may include:

  • Holding Your Urine Not going to the bathroom when you have to or not emptying your bladder completely can lead to a buildup of bad bacteria in your bladder.
  • Having Recently Used a Bladder or Urinary Catheter These are flexible tubes that drain urine from your bladder into a bag if you can’t urinate on your own. They’re also used after some surgeries.
  • Previous UTIs If you’ve had a UTI in the past, you may be at a higher risk for developing another one.
Some health conditions can also increase the chance of getting a UTI:

  • Kidney Stones Kidney stones can block the flow of urine, which increases the risk of harmful bacteria developing in the bladder.
  • Diabetes Diabetes can suppress the immune system, increasing the susceptibility to illness and infection.
  • Weakened Immune System Any illness that involves a weakened immune system can make it harder for your body to fight off an infection.
If you’re sexually active, additional risk factors may increase your chance of getting a UTI:

  • Sexual Intercourse The bacteria that cause UTIs live in the area around your anus. Having sex can move bacteria toward the front, where it can more easily enter your urethra and travel to your bladder.
  • Unwashed Sex Toys If sex toys aren’t properly washed, they can introduce bacteria near the urethra.

  • Unlubricated Condoms Using condoms without lubrication can irritate the skin near the urethra and increase the chance of developing a UTI.

Anatomy can also affect the chances of developing a UTI, as females have shorter urethras than males. This makes it easier for an infection to travel to the bladder.

Additionally, older age may also be a risk factor, as UTIs are more common in people over 50.

How Common Are UTIs?

UTIs are common. Men and women can get UTIs, but they are especially prevalent among women.

Approximately 40 to 60 percent of women will experience a UTI, whereas only about 12 percent of men will have a UTI in their lifetime.

Similarly, UTIs are more common in girls than boys.

How to Prevent UTIs

You can take steps to reduce your chance of getting a UTI. Here are some helpful tips:

  • Stay hydrated. Drinking plenty of water dilutes urine, which causes you to urinate more. This helps rid the body of a potential infection.
  • Completely empty the bladder when you urinate. This helps prevent bacteria from growing in the bladder.
  • Wipe front to back. Good bathroom hygiene helps prevent bacteria around the anus from spreading to the urethra.
  • Take showers instead of baths. Baths can irritate the urethra and promote the growth of bacteria.

  • Consider cranberry extracts or probiotics. These may help prevent a UTI, but be sure to talk to your doctor first before trying them.

Some physicians may recommend wearing cotton underwear and loose-fitting clothing to help prevent a UTI.

 However, other physicians may not agree based on the results of the aforementioned “B-Thong” study. Reach out to your doctor to determine what’s best for you.
If you’re sexually active, consider these practices to help prevent a UTI:

  • Wash your hands before sex or masturbation. Washing your hands can help prevent bacteria from transferring to the genital area during fingering.

  • Urinate before and after sex. This helps rid the body of any bacteria that may be in the urethra. For a similar reason, it’s also helpful to clean your genital area before and after sex.

  • Avoid using certain forms of birth control. These include diaphragms and spermicide.
  • Use lubricated condoms. Unlubricated condoms can cause irritation near the urethra.
  • Wash sex toys. Sex toys that go into your anus or your partner’s anus should be thoroughly washed before touching other genital areas.

It’s also advised to avoid vaginal sprays, douches, or powders, as these products can irritate the urethra.

If you’re experiencing menopause, talk to your doctor about using topical or vaginal estrogen. This can help prevent the vaginal dryness that may cause a UTI.

The Takeaway

UTIs are typically caused by bacteria that enter the urinary tract. Risk factors differ for women, men, and children. If you’re worried about getting a UTI, talk to your doctor about preventive measures, such as wiping front to back, practicing genital hygiene, and staying hydrated.

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Igor Kagan, MD

Medical Reviewer
Castle Connolly Top Doctor

Igor Kagan, MD, is an an assistant clinical professor at UCLA. He spends the majority of his time seeing patients in various settings, such as outpatient clinics, inpatient rounds, and dialysis units. He is also the associate program director for the General Nephrology Fellowship and teaches medical students, residents, and fellows. His clinical interests include general nephrology, chronic kidney disease, dialysis (home and in-center), hypertension, and glomerulonephritis, among others. He is also interested in electronic medical record optimization and services as a physician informaticist.

A native of Los Angeles, he graduated cum laude from the University of California in Los Angeles (UCLA) with a bachelor's in business and economics, and was inducted into the Phi Beta Kappa honor society. He then went to the Keck School of Medicine at the University of Southern California (USC) for his medical school education. He stayed at USC for his training and completed his internship and internal medicine residency at the historic Los Angeles County and USC General Hospital. Following his internal medicine residency, Kagan went across town to UCLA's David Geffen School of Medicine for his fellowship in nephrology and training at the UCLA Ronald Reagan Medical Center. After his fellowship he stayed on as faculty at UCLA Health.

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She previously worked as an editor and staff writer at Environmental Health News. She holds a master’s degree in journalism from NYU’s Science, Health and Environmental Reporting Program and a bachelor’s degree in biology from College of the Holy Cross.

Konkel lives in Haddon Township, New Jersey, with her husband, daughter, three cats, and dog. When she isn't writing, she handles social media and content marketing for a small veterinary clinic she started with her husband, Neabore Veterinary Clinic.

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