Urinary tract infections (UTIs) typically occur when bacteria from the rectal area enter through the urethra, which is a tube that carries urine, and travel up the urinary tract to the bladder or kidneys.

When a bacterial UTI is present but does not cause symptoms, it is called asymptomatic bacteriuria. These types of infections often affect pregnant women, as well as older adults or those who require a catheter to urinate. Pregnant women are screened for asymptomatic bacteriuria, because it can cause preterm labor and other problems if not treated. Asymptomatic bacteriuria may lead to infections that cause symptoms, but in many cases it does not. It usually goes away without treatment.

Typically, UTIs cause urinary symptoms, such as pain or burning during urination. Some mild bladder infections may go away on their own within a couple of days. Most UTIs clear up quickly with antibiotics and home treatment, which includes drinking plenty of water and urinating frequently. The amount of time required to cure the infection and the need for urine tests will vary with the location (bladder or kidneys), frequency, and seriousness of the infection. Kidney infections and UTIs that are complicated by other factors require longer treatment.

Complications of UTIs are not common but do occur. Serious complications can include permanent kidney damage and widespread infection (sepsis), which can be life-threatening. The risk is greater if the infection is not treated or if the infection does not respond to antibiotics.

Although it is possible to have a relapse of the same infection, most recurrent UTIs are caused by new infections. About 20% to 30% of women have recurrent infections.¹ A rapid relapse usually means that treatment failed or there is another problem affecting the urinary tract (not just the infection). But recurrent UTIs in women usually aren't serious.

UTIs in men

Men sometimes develop uncomplicated urinary tract infections.

UTIs in older men are more often related to prostate problems. This can make them more difficult to treat. Having an enlarged prostate, which is common in older men, can limit the body's ability to pass urine. Repeated UTIs may indicate prostatitis, epididymitis, or another urinary tract problem. For more information, see the topic Prostatitis.