Which of the following is a sign of a kidney infection?

Pain when urinating is a common sign of a kidney infection, also known as pyelonephritis. This pain is often caused by inflammation and irritation of the urinary tract, which occurs when bacteria infect the kidneys and surrounding structures. In addition to pain during urination, individuals with a kidney infection may experience other symptoms such as fever, flank pain (pain in the lower back), chills, and nausea. The presence of pain during urination indicates that the infection has affected the areas responsible for urination, signaling the need for further medical evaluation and treatment.

In contrast, frequent headaches, weight gain, and skin rashes are not typically associated with kidney infections. Frequent headaches may arise from various causes, but they do not specifically indicate a kidney infection. Weight gain could result from several factors and does not relate to the symptoms of a kidney infection. Skin rashes can occur due to numerous dermatological conditions or systemic issues, but they are not a classic sign of infection in the kidneys. Therefore, recognizing pain when urinating as a key symptom helps in understanding and diagnosing kidney infections efficiently.