A kidney infection (also called pyelonephritis) is not the same thing as a simple bladder UTI. It’s a type of urinary tract infection (UTI) that often starts in the bladder and travels upward to one or both kidneys.
This matters because kidney infections need prompt medical treatment. If not treated properly, the infection can cause lasting kidney damage or bacteria can spread into the bloodstream and cause a dangerous infection.
Educational only. Not medical advice or a diagnosis.
Kidney infection vs. UTI
When people say “UTI,” they often mean a lower UTI (bladder infection). A kidney infection is still a UTI—but it’s more likely to make you feel suddenly sick, cause fever, or cause lower back/side pain.
More consistent with a bladder infection
CDC lists bladder infection symptoms such as:
- pain or burning while urinating
- frequent urination
- feeling like you need to urinate even when the bladder is empty
- pressure/cramping low in the abdomen or groin
- bloody urine
More consistent with a kidney infection
CDC lists kidney infection symptoms such as:
- fever
- chills
- lower back pain or pain in the side of your back
- nausea or vomiting
Kidney infection symptoms
NIDDK notes kidney infection symptoms may include fever, pain in your back/side/groin, and painful urination.
Cleveland Clinic lists common symptoms including:
- fever and chills
- pain in your lower back or side
- pain when you pee
- bloody or cloudy urine (that may smell bad)
- urgent or frequent need to pee
How serious is a kidney infection?
A kidney infection is treatable—but it’s not something to “wait out.” Mayo Clinic states kidney infections need prompt treatment; if not treated properly, they can cause kidney damage or spread to the bloodstream and cause a dangerous infection.
Cleveland Clinic notes kidney infections can lead to life-threatening complications, especially in people with weaker immune systems or other underlying issues.
Can it turn into sepsis?
It can. CDC explains that infections leading to sepsis often start in the urinary tract, and without fast treatment, sepsis can quickly lead to tissue damage, organ failure, and death.
This is why fever + back pain + vomiting is treated differently than “just urinary burning.”
Who is more at risk for a kidney infection?
Females and pregnancy
Mayo Clinic lists being female as a risk factor (shorter urethra makes it easier for bacteria to reach the bladder), and notes pregnant women are at even higher risk.
Anything that blocks urine flow
Cleveland Clinic notes risk increases when something prevents you from emptying urine normally—examples include kidney stones, enlarged prostate, and other causes of blockage.
How common are kidney infections in the U.S.?
Cleveland Clinic estimates about 1 in 2,000 people get a kidney infection each year in the U.S.
(That number is not meant to alarm you—just to show this is a real, frequent condition clinicians treat.)
How doctors diagnose a kidney infection
NIDDK notes clinicians diagnose kidney infection using medical history, physical exam, and lab tests, and may also use imaging tests to help diagnose.
Typical evaluation often includes:
- urine testing (to look for infection signs and guide antibiotics)
- imaging when symptoms are severe, complicated, or a blockage/stone is suspected
Kidney infection treatment
NIDDK states kidney infections are treated with antibiotics, and you should finish your medicine even if you start to feel better.
Mayo Clinic also notes treatment often includes antibiotics, sometimes given in the hospital.
If symptoms aren’t improving
Mayo Clinic advises seeing your provider if you have kidney infection symptoms, and also if you’re being treated for a UTI but symptoms aren’t getting better.
Warning symptoms that shouldn’t wait
Seek urgent evaluation if you have kidney infection symptoms plus any of the following:
- Fever and chills with urinary symptoms
- Back/side pain with nausea or vomiting
- Bloody urine plus nausea/vomiting (Mayo specifically flags this as a reason to seek care right away)
- Feeling suddenly very ill, weak, confused, or “getting worse fast” (especially with fever)
If you’re in Houston and your symptoms fit the “warning symptoms that shouldn’t wait,” it’s reasonable to get evaluated—particularly if fever/chills, flank pain, or vomiting are involved.
Post Oak ER states it is open 24/7 with board-certified physicians available 24/7.
They also state they’re located off San Felipe St. near The Galleria and Uptown Park, and are easy to reach from areas like Uptown, the Energy Corridor, Westchase, Midtown, and the Heights.