Kidney Infection

A kidney infection — also called pyelonephritis — is a type of urinary tract infection (UTI) that usually begins in your bladder and travels to your kidneys. Bacteria are the most common cause of kidney infections and they are treated with antibiotics.

If you have a kidney infection, UPMC experts will provide personalized care. Their goal is to provide fast treatment that relieves your symptoms and reduces your risk of complications.

On this page

• What Is Kidney Infection?
• What Are the Symptoms of Kidney Infection?
• How Do You Diagnose Kidney Infection?
• How Do You Treat Kidney Infection?

What Is Kidney Infection?

A kidney infection — also called pyelonephritis — is a type of urinary tract infection (UTI) that usually begins in your bladder and travels to your kidneys. Bacteria are the most common cause of kidney infection and they are treated with antibiotics.

What causes kidney infection?

Most kidney infections are caused by bacteria, but they can also be caused by viruses. Kidney infections typically start in the bladder, which is in the lower part of your urinary tract, and travel to one or both kidneys in your upper urinary tract.

What are kidney infection risk factors and complications?

Kidney infection risk factors

You may be at higher risk of developing a kidney infection if you:

• Are a woman.
• Are pregnant.
• Have a current bladder infection or have had one in the past year.
• Have a condition called vesicoureteral reflux, which causes urine to back up into your kidneys.
• Have diabetes.
• Have had a kidney transplant.
• Have nerve damage to your bladder.
• Have problems with your immune system.
• Have problems with your urinary tract, such as blockages or problems with urine flow.

Complications of kidney infections

If left untreated, kidney infections can cause:

• High blood pressure.
• Kidney failure.
• Kidney scarring — which can lead to chronic kidney disease.
• Sepsis.

Hospitalization and even death can occur in rare cases.

How can I prevent kidney infection? 

Kidney infections are caused by bacteria that travel from the bladder to the kidneys. Preventing bladder infections may reduce your risk of kidney infections.

You may be able to reduce your risk of bladder and kidney infections by:

• Drinking plenty of plain water daily — Talk to your doctor about how much water you need to drink based on your activity level, the weather, and other health conditions.
• Maintaining good hygiene — Change out of wet or sweaty underwear and shower regularly.
• Urinating after sex — Peeing after sex can flush bacteria from the urethra (the opening where urine comes out) in both men and women.
• Urinating more often — Urinating every three to four hours and avoiding “holding it” when you have the urge to urinate can reduce the risk of bacteria growing in your bladder.
• Wiping from front to back after using the toilet — For women, this method helps keep bacteria from the bowels from getting into the urethra (the opening where urine comes out).

How common is kidney infection?

Kidney infections affect one in 2,000 people in the U.S. each year and are a common cause of hospital visits for UTIs. Females tend to be at a higher risk for developing kidney infections than men.

Back to top.

What Are the Signs and Symptoms of Kidney Infection?

What are the warning signs of a kidney infection?

In adults and children, kidney infection may cause:

• Fever or chills.
• Frequent, painful urination.
• Nausea or vomiting.
• Pain in your back, side, or groin.
• Urine that is cloudy, dark, bloody, or foul-smelling.

A fever may be the only symptom of a kidney infection in very young children.

Kidney infection may not cause typical symptoms in older people, making it a challenge to diagnose.

Older people with a kidney infection may have:

• Confusion.
• Hallucinations.
• Problems with speech.

When should I see a doctor about my kidney infection symptoms?

If left untreated, kidney infections can be painful and cause serious complications. If you have symptoms of a kidney infection, you should schedule an appointment with your doctor right away.

Can a kidney infection go away on its own?

Untreated kidney infections can cause serious complications and are usually treated with antibiotics. If you have symptoms, see your doctor immediately.

Back to top.

How Do You Diagnose Kidney Infection?

Your doctor will perform a physical exam, talk to you about your health history, and order tests to diagnose a kidney infection.

What to expect during your visit

During your visit, your doctor will:

• Ask about any medications you’re taking.
• Order tests.
• Perform a physical exam.
• Review your health history.

Tests to diagnose kidney infection

Your doctor may order urine tests, including:

• Urinalysis — Looks for abnormalities in your urine, such as bacteria and white blood cells.
• Urine culture — Identifies the type of bacteria causing your infection so your doctor can prescribe the best treatment.

Other less common tests include:

• CT scan — A test that creates images of the organs, bones, and tissues in your body.
• Digital rectal exam (DRE) — Your doctor may perform this test to check for signs of an enlarged prostate in men with kidney infection symptoms.
• MRI — Uses a combination of large magnets, radio frequencies, and a computer to produce detailed images of organs and structures within your body.
• Ultrasound — Uses sound waves to create images of your organs to check for problems.

How can I test for a kidney infection at home?

Kidney infections can be serious if left untreated. Although at-home kidney infection tests are available, you should see your doctor for an accurate diagnosis and prompt treatment.

Kidney infection prognosis

Most people respond well to antibiotic therapy and recover completely from kidney infections. However, some may need more than one round of antibiotics or develop recurrent infections. In rare cases, untreated kidney infections may cause permanent kidney damage.

Back to top.

How Do You Treat Kidney Infection?

The goal of kidney infection treatment is to provide fast treatment that relieves symptoms and reduces your risk of complications.

Treatment options may include:

Lifestyle changes

Lifestyle changes alone are not enough to treat a kidney infection. However, lifestyle changes may help to prevent future kidney infections.

Your doctor may recommend:

• Drinking plenty of plain water.
• Urinating more often.
• Urinating after sex.
• Wiping from front to back after using the toilet (for women).

Medicine to treat kidney infection

Your doctor may prescribe oral antibiotics to treat your kidney infection. You may need to take antibiotics for a few days or weeks. It’s important to take all your antibiotics as prescribed by your doctor to make sure your infection is completely gone.

What’s the best treatment for a kidney infection?

Antibiotics are typically the best treatment for kidney infection. The best type of antibiotic is based on urine culture results.

Options include:

• Amoxicillin or augmentin.
• Ceftriaxone or cephalexin.
• Ciprofloxacin or levofloxacin.
• Trimethoprim-sulfamethoxazole (TMP-SMX).

If you have a severe kidney infection and oral antibiotics aren’t helping your symptoms, you may need to be admitted to the hospital so you can receive intravenous (IV) antibiotics.

Other treatments for kidney infection

If you have an enlarged prostate, kidney stone, or another urinary tract condition causing your kidney infections, your doctor may recommend surgery or another treatment to reduce your risk of future kidney infections.

Why choose UPMC for kidney infection care?

When you choose UPMC for kidney infection care, you will receive:

• Access to world-class nephrology expertise — Our world-renowned experts treat the full spectrum of kidney diseases  using the latest diagnostic and treatment techniques.
• A full range of treatment options — We'll work with you to develop a treatment plan that relieves symptoms and reduces your risk of complications.
• Multidisciplinary care — We partner with urologists, primary care providers, and other experts to provide complete kidney care.

Back to top.

By UPMC Editorial Staff. Last reviewed on 2025-04-24 by Cary Shiwarski, MD, PhD.