Can a UTI Become a Kidney Infection?

Reviewed on 2/22/2021

What are UTIs and kidney infections?

A urinary tract infection occurs when bacteria enter the urinary system. A kidney infection occurs when bacteria move up the urinary tract and into the kidneys. A UTI may become a kidney infection if it is left untreated.
A urinary tract infection occurs when bacteria enter the urinary system. A kidney infection occurs when bacteria move up the urinary tract and into the kidneys. A UTI may become a kidney infection if it is left untreated.

A urinary tract infection (UTI) or kidney infection can affect your quality of life in the short term and your long-term health. It is important that you know the difference between these two conditions, their symptoms, and how to treat them.

Understanding how kidney infections are related to UTIs can help you prevent future occurrences of either condition.

It's important to understand the differences between the symptoms of these two conditions and the steps you can take to prevent further damage.

What is a urinary tract infection?

UTI, or urinary tract infection, happens when bacteria enter into any part of your urinary system. This system includes your urethra, bladder, and kidneys. 

These bacteria grow and multiply, which causes an infection.

What is a kidney infection?

If left untreated, the bacteria that cause your urinary tract infection can move up from your urinary system to your kidneys. This causes pyelonephritis, the scientific term for kidney infection. However, UTIs are not the only source of kidney infections.

Symptoms of UTIs and kidney infections

While UTIs and kidney infections are related, they can have different symptoms. Not all of these symptoms happen every time, and they may show up at different times. Your symptoms might begin suddenly. Some of these may simply be early warnings.  

Symptoms of urinary tract infection

You may have an uncomplicated urinary tract infection if you start experiencing some or all of the following symptoms:

  • Pain or a burning feeling when you urinate
  • Sudden urge to urinate more often than normal, especially at night
  • Cloudy urine
  • Blood in your urine
  • Lower abdominal pain 

In children or infants, watch out for:

  • Fever 
  • Irritable and refuses to feed.
  • Wetting themselves or the bed, even if potty-trained.

Symptoms of kidney infection

If you have a kidney infection, you may notice one or more of the following symptoms:

  • Fever
  • Nausea and/or vomiting
  • Pain in your back, side(s), or groin
  • Chills
  • Urinating more often than usual
  • An urgent need to urinate, even if you just went
  • Pain or burning sensation when urinating
  • Pus or blood in your urine
  • Cloudy or bad-smelling pee 

It is important that you call your doctor if you notice any of these symptoms. 

If you are currently taking medication to treat a UTI and you have any of these symptoms, call your doctor as soon as possible.

Causes of UTIs and Kidney Infections

There are several causes and risk factors for UTIs and kidney infections. 

Some risk factors are beyond your control, but others are not. Reducing your risks can even help you prevent an aneurysm or a stroke.

Causes of urinary tract infection 

Urinary tract infections mostly occur when your urinary tract is infected by bacteria from your skin or the digestive system. These bacteria may enter your urinary system through your urethra when you wipe your bottom or while you are having sex.

You may also be more likely to get a urinary tract infection if you:

Have a condition that is blocking your urinary tract, such as kidney stones

Women may be more likely to get UTIs because their urethra is shorter than and closer to their anus than men’s. Women may also be more likely to get UTIs after sexual intercourse if they use a contraceptive diaphragm or condoms that are coated with spermicide.

Causes of kidney infection 

Kidney infections occur when bacteria get into the urethra and travel up into your bladder and then up into your kidneys. They are typically caused by a bacterium called Escherichia coli, or E. coli, which normally lives in your bowel

E. coli is harmless when in your bowel, but it will cause infection if it finds its way into your urinary system. You may get a kidney infection during sex or when wiping your bottom if you are not careful. 

Kidney infections may also occur without traveling up from your urinary tract. This can occur if you have:

Diagnosis for UTIs and kidney infections

Only a licensed healthcare professional can diagnose a urinary tract or kidney infection.

UTI diagnosis

To diagnose a urinary tract infection, your doctor will carefully review your medical history and do a physical examination to check for signs and symptoms.

They may also order tests like:

  • Urinalysis: After taking your urine sample, your doctor will take it for lab testing to check for red blood cells and white blood cells, bacteria, and proteins. The presence of these may indicate you have a UTI. 
  • Urine culture: Urine cultures aren’t a regular part of a typical urinalysis, so your doctor may do one of these too. In a urine culture, a urine sample is taken to a lab where bacteria are grown from it, which can help doctors diagnose which bacteria are causing the UTI.

If UTIs become a recurring problem for you, your doctor may order additional tests to examine your bladder and urinary tract adn to check for blockages like tumors or kidney stones. 

Kidney infection diagnosis

To diagnose a kidney infection your doctor will take your medical history, a physical exam, and some tests. They may ask if you have had health conditions that might make you prone to kidney infections. 

Doing a physical exam will help your doctor detect any signs and symptoms of kidney infection.

If you are male, your doctor may perform a digital rectal examination (DRE). This checks if you have a swollen or enlarged prostate that may be blocking your bladder.

Some of the tests your doctor may do include:

Treatments for UTIs and kidney infections


After making a diagnosis and determining that you have a urinary tract infection, your doctor may prescribe antibiotics to get rid of the bacteria causing your infection. 

You should inform your doctor if you have any drug allergies before taking the medication. Call your doctor if you develop any side effects like rashes while taking your antibiotic.

Kidney infection 

For kidney infections, your doctor may prescribe antibiotics to get rid of the bacteria causing the infections. 

Your doctor may also give you pain relievers to manage the painful symptoms that can accompany a kidney infection. Depending on the severity of your infection and other factors in your personal medical history, you may need to be admitted to the hospital for further monitoring. 

It's also important that you drink a lot of fluids. This will help prevent dehydration and flush the bacteria out of your kidneys. 


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American Kidney Fund: "Kidney infection."

Centers for Disease Control and Prevention: "Urinary Tract Infection."

Johns Hopkins Medicine: "Urinary Tract Infections."

Merck Manual: “Urinalysis and Urine Culture."

National Association For Continence: "HOW DO I KNOW IF I HAVE A UTI OR A KIDNEY INFECTION?"

National Health Service: "Kidney Infection."

National Health Service: "Urinary tract infections (UTIs)."

NHSinform: "Kidney infection."

NHSinform: "Urinary Tract Infections."

National Institute of Diabetes and Digestive and Kidney Diseases: "Diagnosis of Kidney Infection (Pyelonephritis)."

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