Kidney Infection: Causes, Symptoms, and Treatment
Medically reviewed by Achuta Uppu, MD, Internal Medicine. Last reviewed: October 23, 2026.
What kind of doctor treats Kidney Infection?
A primary care doctor can often start the evaluation and treatment of a kidney infection. A urologist, a doctor who treats the urinary tract, may help if a blockage is the cause. People who are very sick may be cared for in a hospital. A direct primary care or concierge doctor can be a first stop for an evaluation and can refer you to a specialist when needed.
What is a kidney infection?
A kidney infection is also called pyelonephritis. It happens when germs get into one or both of your kidneys. Most kidney infections start as a bladder infection in the lower urinary tract. If a bladder infection is not treated or does not go away, it can spread to one or both kidneys. Bacteria are often the cause, and viruses are a less common cause.
Symptoms
Symptoms of a kidney infection vary by age. They may include:
- Fever and chills.
- Cloudy, dark, bloody, or foul-smelling urine.
- Frequent, painful urination.
- Pain in your back, side, or groin.
- Nausea or vomiting.
Children younger than age 2 years may only have a high fever. They may also have trouble feeding and gain weight poorly.
Causes and who gets it
Bacteria that live in your bowel can get into your urinary tract and cause an infection. Sometimes your blood carries harmful bacteria or viruses from another part of your body to your kidneys. Rarely, a kidney infection can start after surgery. A blockage in the urinary tract can also cause one. Examples are a kidney stone or an enlarged prostate.
How doctors diagnose it
Doctors use your medical history, a physical exam, and lab and imaging tests. A urinalysis checks a urine sample for blood and white blood cells. Your body makes white blood cells when it is fighting an infection caused by bacteria. A urine culture identifies some common types of bacteria in your urine. It may help show whether antibiotics are a treatment option. Blood tests look for serious infections and can show how well your kidneys are working. Doctors may also use imaging tests such as a CT scan, an MRI, a radionuclide scan, or an ultrasound. An ultrasound uses sound waves to make a picture of your organs.
Treatment
If bacteria cause your kidney infection, your doctor will prescribe an antibiotic, a medicine that kills bacteria. Your doctor may change the antibiotic based on your lab results. You may take antibiotics by mouth, through an intravenous (IV) line, or both. If you are very sick, you may go to a hospital, where you may get IV fluids.
If a blockage caused the infection, you may need surgery or another procedure to treat the blockage. Small changes to daily habits may help prevent kidney infections. You can drink enough liquids, wipe front to back, use the bathroom when you feel the urge, and fully empty your bladder.
When to see a doctor
Seek care right away if you have kidney infection symptoms. If you think you have a bladder infection, or an infection that seems to be getting worse, contact your doctor. See your doctor right away if your symptoms return after you finish treatment.
A kidney infection could lead to sepsis, which can be life threatening, although this is uncommon. Signs of sepsis can include fever and chills with confusion, rapid breathing and heart rate, severe pain, or shortness of breath. Call 911 or go to the emergency room if you have these signs.
How a direct primary care or concierge doctor fits in
A direct primary care doctor charges a flat monthly fee instead of billing insurance, while a concierge doctor usually charges more and often works alongside insurance. Either one can look at your symptoms, order a urine test, and send you to a hospital or a urologist when needed.
Common questions
Is a kidney infection serious?
Yes, it can be serious. Although uncommon, a kidney infection could lead to sepsis, which can be life threatening. That is why you should seek care right away if you have symptoms.
Is a kidney infection the same as a bladder infection?
No, they affect different parts of the urinary tract. A kidney infection is in the upper urinary tract, while a bladder infection is in the lower urinary tract. A bladder infection that is not treated can spread to the kidneys.
How is a kidney infection treated?
Doctors treat a kidney infection caused by bacteria with antibiotics. You may take them by mouth, through an IV, or both. People who are very sick may go to a hospital.
Can a kidney infection be prevented?
Daily habits may help prevent a kidney infection, but scientists are still trying to understand the best ways to prevent bladder infections, where many kidney infections start. Caring for your urinary tract matters. Drinking enough liquids and wiping front to back may help.
Can a kidney infection come back?
Yes, symptoms can return after treatment. If they do, see your doctor right away. Your doctor may order another urine culture or imaging tests. If tests show an infection, your doctor may prescribe different antibiotics or antibiotics for a longer time.
Sources
- NIDDK - Symptoms & Causes of Kidney Infection (Pyelonephritis)
- NIDDK - Diagnosis of Kidney Infection (Pyelonephritis)
- NIDDK - Treatment for Kidney Infection (Pyelonephritis)
Medical Disclaimer
This content is for general educational and informational purposes only and is not medical advice. It is not a substitute for professional medical advice, diagnosis, or treatment, and reading it does not create a doctor-patient relationship. Always seek the advice of your physician or another qualified health provider with any questions about a medical condition, and never disregard or delay seeking professional advice because of something you read here. If you think you may have a medical emergency, call 911 (or your local emergency number) immediately.
