Urinary tract infections occur when bacteria enter the urethra and infect the urinary tract. This can happen during sexual intercourse, due to a genetic predisposition, or due to poor hygiene, such as not wiping properly.

Urinary tract infections are the most commonly treated non-hospital infection in the United States and affect about 50–60 percent of women over the course of their lives. About a quarter of women also report re-infections within six months.

Urinary tract infections can affect anyone, they are approximately 30 times more common in women because women have shorter urethras that are closer to the anus – a common source of bacteria. Broken down, “the groups at highest risk of infection are sexually active women, older women and immunocompromised men and women,” says Comiter.

When urinary tract infections only affect the bladder, they are not considered dangerous and usually heal without treatment—although antibiotics are often prescribed to speed up the healing process from weeks to days. However, when these infections spread to the kidneys, bloodstream, or other areas of the reproductive system, they can lead to serious complications such as blood poisoning, sepsis, kidney damage, or kidney failure.

If left untreated, “a very small percentage of these cases can even be life-threatening,” explains Jacob Lazarus, an infectious disease physician at Massachusetts General Hospital and bacterial cell biologist at Harvard Medical School.