A kidney infection, known medically as pyelonephritis, is a severe form of urinary tract infection (UTI) that has ascended from the bladder to one or both kidneys. This condition is caused by bacteria, most often E. coli, traveling up the urinary tract. Since the kidneys filter waste and regulate the body’s fluid balance, an infection there can cause immediate illness and lead to permanent damage if not treated promptly. Determining the appropriate level of care depends on the severity of your specific symptoms.
Common Symptoms of a Kidney Infection
A kidney infection often presents with a distinct set of symptoms that differentiate it from a simple bladder infection. One of the most telling signs is the onset of a high fever, typically reaching 101°F (38.3°C) or higher, often accompanied by shaking chills.
A significant sign is pain in the back, side, or groin, specifically known as flank pain, usually felt just under the ribs. This pain is localized to the area where the kidneys are situated and indicates that the infection has reached the upper urinary tract. Nausea and vomiting are also common, which can quickly lead to dehydration, further complicating the illness.
Symptoms shared with a lower UTI, such as a frequent or urgent need to urinate, a burning sensation during urination, and cloudy or foul-smelling urine, will often still be present. The combination of these symptoms, particularly the presence of fever and flank pain, strongly suggests pyelonephritis. If you experience this combination, you must seek medical attention immediately.
Immediate Emergency Warning Signs
An immediate trip to the Emergency Room is necessary if your symptoms indicate the infection has become life-threatening or is causing rapid deterioration. The most concerning risk is sepsis. Symptoms of septic shock include a rapid heart rate, low blood pressure, and a sudden, dramatic drop in body temperature.
Severe, unmanageable pain in the flank or abdomen that prevents you from finding a comfortable position is an indication for emergency care. Likewise, if you are experiencing uncontrollable vomiting and cannot keep any liquids down, you are at risk for severe dehydration, which requires intravenous fluids.
Any sign of confusion, disorientation, or an altered mental state warrants an immediate ER visit, as this can be a symptom of severe systemic infection or sepsis. People with underlying conditions, such as diabetes, a compromised immune system, or who are pregnant, should seek emergency care sooner, as their risk of rapid complication is much higher. Additionally, if you have difficulty breathing or notice a significant decrease in urine output, you need emergency medical attention.
Navigating Non-Emergency Care
If you recognize the common symptoms of a kidney infection but do not have any of the immediate emergency warning signs, you should still seek medical attention the same day. Non-emergency options include contacting your primary care physician, visiting an urgent care center, or using a virtual care provider if your condition is stable. The goal is to obtain a diagnosis and begin antibiotic treatment without delay to prevent the infection from escalating.
When seeking non-emergency care, a medical professional will perform a urinalysis and a urine culture to identify the specific bacteria causing the infection. These tests are necessary to ensure the correct antibiotic is prescribed, as resistance is becoming increasingly common. Even if you feel well enough to wait, delaying care can lead to the infection spreading and causing serious harm.
The healthcare provider will assess your overall health, looking for factors such as recent antibiotic use or a history of kidney stones. They will also check your vital signs to ensure you are not showing early signs of a systemic reaction or severe dehydration. If the initial assessment suggests a stable condition, you will likely be sent home with a prescription for oral antibiotics to begin immediately.
Expected Treatment and Follow-Up
Treatment for a kidney infection centers around eliminating the bacteria with antibiotics. If you are sick enough to be admitted to the hospital, you will receive intravenous (IV) antibiotics and fluids. For outpatient care, a course of oral antibiotics is typically prescribed for seven to fourteen days.
Even if your symptoms begin to clear up within a few days, you must complete the entire course of antibiotics as prescribed. Stopping the medication early can allow residual bacteria to survive, potentially causing the infection to return and increasing the risk of antibiotic resistance. Supportive care, such as drinking plenty of water and using acetaminophen for pain and fever, is also recommended during recovery.
A follow-up is necessary to confirm that the infection has completely cleared, usually involving a repeat urine culture one to two weeks after you finish the antibiotic course. If the infection does not resolve or if symptoms worsen after 48 to 72 hours of starting treatment, you must contact your provider immediately, as a change in antibiotic or further evaluation may be needed. In complicated cases, the doctor may order imaging tests like a CT scan or ultrasound to check for underlying issues such as kidney stones or blockages.