If left untreated, a urinary tract infection (UTI) can lead to serious health complications. These include:

1. Kidney infection (pyelonephritis): If bacteria from a UTI ascend to the kidneys, it can cause a kidney infection which can result in high fever, chills, back or abdominal pain, nausea, and vomiting. It requires immediate medical attention and can cause kidney damage and potentially lead to chronic kidney disease.

1. Septicemia (Sepsis): If bacteria from a UTI enter the bloodstream, it can cause sepsis, a life-threatening response of the body to an infection. Symptoms of sepsis include high fever, rapid heart rate, rapid breathing, confusion, and decreased urine output. Without prompt medical intervention, sepsis can lead to septic shock, organ failure, and even death.

1. Recurrent infections: When a UTI is left untreated, it can lead to recurrent infections. The bacteria can persist in the urinary tract, causing repeated episodes of UTIs. Recurrent UTIs can be frustrating and may require prolonged or more aggressive treatment to eradicate the infection completely.

1. Complications during pregnancy: UTIs during pregnancy can increase the risk of complications such as preterm birth, low birth weight, and neonatal infections. Pregnant women should seek timely treatment for UTIs to ensure a healthy pregnancy outcome.

1. Chronic kidney infection: A kidney infection that goes untreated or is inadequately treated can develop into a chronic kidney infection. This can cause persistent or recurring kidney infections that can lead to kidney damage over time. Chronic kidney infections can result in kidney scarring, impaired kidney function, and an increased risk of complications such as kidney stones and chronic kidney disease.

It is important to seek medical attention promptly and follow the prescribed treatment to prevent the progression of a UTI and the associated serious health complications.