Pyelonephritis (Upper UTI)
What is Pyelonephritis (Upper UTI)?
Pyelonephritis is a serious kidney infection that affects one or both kidneys. It occurs when bacteria travel up from your bladder through the tubes called ureters and reach the kidney tissue. This infection causes inflammation in the kidneys and can damage them if left untreated.
Unlike a simple bladder infection, pyelonephritis affects the deeper kidney structures. It usually causes fever, back pain, and feeling very sick. Most cases happen when bacteria from a lower urinary tract infection spread upward to the kidneys. Women are more likely to develop this condition than men.
Quick diagnosis and treatment are essential to prevent permanent kidney damage. With proper antibiotics and care, most people recover fully within a few weeks. However, untreated pyelonephritis can lead to sepsis, a life-threatening blood infection, or chronic kidney problems.
Symptoms
- High fever, often above 101°F
- Pain in your back, side, or groin
- Nausea and vomiting
- Frequent, painful urination
- Cloudy or bloody urine
- Foul-smelling urine
- Chills and shaking
- Confusion, especially in older adults
- General feeling of being unwell
- Pressure or discomfort in your lower abdomen
Most people with pyelonephritis feel very sick and know something is wrong. Some people may start with mild bladder infection symptoms that worsen quickly over hours or days.
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Causes and risk factors
Pyelonephritis most often starts with bacteria entering your urinary tract through the urethra. The bacteria multiply in your bladder, then travel up the ureters to reach your kidneys. The most common culprit is E. coli, a bacteria normally found in your digestive system. Other bacteria and occasionally fungi can also cause kidney infections.
Risk factors include being female, having kidney stones or urinary tract blockages, using a urinary catheter, having diabetes, having a weakened immune system, and experiencing nerve damage that affects bladder function. Pregnancy also increases risk because hormonal changes can slow urine flow. Structural abnormalities in the urinary tract and recent urinary procedures can make infections more likely. Not emptying your bladder fully or holding urine for long periods may also contribute to infection risk.
How it's diagnosed
Doctors diagnose pyelonephritis through a combination of your symptoms, physical exam, and laboratory tests. A urine test is the most important diagnostic tool. Your doctor will check for white blood cells, red blood cells, bacteria, and nitrites in your urine. Nitrites appear when certain bacteria convert nitrates in your urine, signaling an active bacterial infection that may have reached your kidneys.
Rite Aid offers urine testing that can detect nitrite and other markers of infection. A positive nitrite test suggests bacteria are present and may have ascended to your kidneys. Your doctor may also order a urine culture to identify the specific bacteria and determine which antibiotics will work best. Imaging tests like ultrasound or CT scans may be needed if you have recurrent infections or severe symptoms.
Treatment options
- Antibiotics for 7 to 14 days, sometimes longer depending on severity
- Drinking plenty of water to help flush bacteria from your urinary system
- Taking pain relievers like acetaminophen or ibuprofen for discomfort and fever
- Getting plenty of rest while your body fights the infection
- Hospital admission for intravenous antibiotics if you cannot take pills or are severely ill
- Treating underlying conditions like kidney stones or diabetes that contributed to infection
- Following up with your doctor to ensure the infection has cleared
- Avoiding caffeine and alcohol during treatment
- Urinating frequently and not holding urine
- Wiping front to back after using the bathroom to prevent bacteria spread
Concerned about Pyelonephritis (Upper UTI)? Get tested at Rite Aid.
- Simple blood draw at your nearest lab
- Results in days, not weeks
- Share results with your doctor
Frequently asked questions
A bladder infection, also called cystitis, affects only your bladder and lower urinary tract. Pyelonephritis is more serious because the infection has spread to your kidneys. Pyelonephritis causes fever, back pain, and severe illness, while bladder infections usually cause only urinary symptoms without fever.
Symptoms can develop rapidly over a few hours or gradually over a day or two. Most people notice they feel sick quite suddenly, with fever and back pain appearing quickly. Some people experience bladder infection symptoms first, which then progress to kidney infection signs within 24 to 48 hours.
No, pyelonephritis requires antibiotic treatment and will not resolve on its own. Without treatment, the infection can cause permanent kidney damage, spread to your bloodstream, or become life-threatening. Always see a doctor if you suspect a kidney infection.
Most people start feeling better within 2 to 3 days of starting antibiotics. However, you must finish the entire antibiotic course, which typically lasts 7 to 14 days. Full recovery usually takes several weeks, and you may feel tired during this time.
While over-the-counter urine test strips can detect signs of infection, you need proper medical evaluation for suspected pyelonephritis. Rite Aid offers urine testing that checks for nitrites and other infection markers. However, a doctor should evaluate positive results and prescribe antibiotics if needed.
Most people who receive prompt treatment recover fully without lasting damage. However, delayed treatment, recurrent infections, or underlying kidney problems can lead to scarring or chronic kidney disease. This is why early diagnosis and proper antibiotic treatment are so important.
Women have a shorter urethra, the tube that carries urine from the bladder out of the body. This shorter distance makes it easier for bacteria to reach the bladder and potentially travel up to the kidneys. Sexual activity and pregnancy also increase infection risk in women.
Yes, treating bladder infections promptly prevents them from spreading to your kidneys. Drink plenty of water, urinate after sex, wipe front to back, and avoid holding urine for long periods. Your doctor may recommend low-dose antibiotics or other preventive measures if you have recurrent infections.
Seek emergency care if you have high fever with severe back pain, cannot keep down liquids or medications, see blood in your urine, or feel confused or extremely weak. These signs suggest a severe infection that may need hospital treatment with intravenous antibiotics.
Yes, children can develop kidney infections, though they are less common than in adults. Children with pyelonephritis may have fever, vomiting, and abdominal pain rather than typical back pain. Any child with fever and urinary symptoms should see a doctor promptly to prevent kidney damage.