A kidney infection, also known as pyelonephritis, occurs when bacteria enter the kidneys, often through the urinary tract. This infection can cause symptoms such as fever, chills, back pain, and frequent urination. It is more common in women than men and can develop from untreated urinary tract infections. If left untreated, a kidney infection can lead to serious complications, including kidney damage or sepsis. Treatment typically involves antibiotics to eliminate the infection. Staying hydrated and seeking medical attention for urinary symptoms can help prevent kidney infections from occurring.