A kidney infection, medically known as pyelonephritis, is a serious type of urinary tract infection (UTI) that occurs when bacteria travel from the bladder to one or both kidneys. Unlike a simple bladder infection, a kidney infection requires prompt medical treatment because it can lead to permanent kidney damage or spread to the bloodstream if left untreated.
Health experts advise seeking medical care immediately if symptoms of a kidney infection develop, especially when accompanied by fever or severe back pain.
What Is a Kidney Infection?
The kidneys filter waste products from the blood and produce urine.
A kidney infection develops when bacteria—most commonly Escherichia coli (E. coli)—enter the urinary tract and travel upward into the kidneys.
Although less common, kidney infections can also occur when bacteria spread through the bloodstream from another part of the body.
What Causes a Kidney Infection?
Several factors increase the risk of developing pyelonephritis, including:
- Untreated urinary tract infections.
- Kidney stones that block urine flow.
- Enlarged prostate in men.
- Structural abnormalities of the urinary tract.
- Vesicoureteral reflux (a condition where urine flows backward toward the kidneys).
- Pregnancy.
- Diabetes.
- A weakened immune system.
- Long-term use of urinary catheters.
Women are generally at higher risk because they have a shorter urethra, allowing bacteria to reach the bladder more easily.
Symptoms
Kidney infections often develop suddenly.
Common symptoms include:
- Fever and chills.
- Pain in the side, back, or lower abdomen.
- Pain or burning during urination.
- Frequent or urgent urination.
- Cloudy or foul-smelling urine.
- Blood in the urine.
- Nausea and vomiting.
- Fatigue.
Symptoms are usually more severe than those of a simple bladder infection.
Possible Complications
Without prompt treatment, a kidney infection can lead to:
- Permanent kidney damage.
- Kidney abscess.
- Sepsis (a life-threatening bloodstream infection).
- Recurrent kidney infections.
- Pregnancy complications in pregnant women.
Early treatment greatly reduces the risk of these complications.
How Is a Kidney Infection Diagnosed?
Your healthcare provider may recommend:
- A review of your symptoms and medical history.
- A physical examination.
- Urinalysis.
- Urine culture to identify the bacteria causing the infection.
- Blood tests.
- Ultrasound or CT scan if a blockage or kidney stone is suspected.
These tests help confirm the diagnosis and determine the severity of the infection.
Treatment
Treatment usually includes:
Antibiotics
Antibiotics are the main treatment and should be taken exactly as prescribed, even if symptoms improve.
Fluids
Drinking enough fluids helps flush bacteria from the urinary tract unless your healthcare provider advises otherwise.
Pain Relief
Pain-relieving medications may be recommended to reduce discomfort and fever.
Hospital Care
People with severe infections, pregnancy, persistent vomiting, or signs of sepsis may require hospital treatment with intravenous (IV) antibiotics.
How Can You Prevent Kidney Infections?
You can lower your risk by:
- Drinking plenty of water.
- Treating urinary tract infections promptly.
- Practising good personal hygiene.
- Emptying your bladder regularly.
- Urinating after sexual activity.
- Managing diabetes effectively.
Preventing bladder infections can help prevent kidney infections.
When Should You Seek Emergency Care?
Seek immediate medical attention if you experience:
- High fever with chills.
- Severe pain in your side or back.
- Blood in your urine.
- Persistent vomiting.
- Confusion or extreme weakness.
- Symptoms of a urinary tract infection that suddenly become much worse.
These symptoms may indicate a serious kidney infection requiring urgent treatment.
The Bottom Line
A kidney infection is a serious medical condition that should never be ignored. Symptoms such as fever, severe back or side pain, painful urination, and blood in the urine require prompt medical evaluation. With early diagnosis and appropriate antibiotic treatment, most people recover fully and avoid long-term kidney damage.
Disclaimer: This article is for informational purposes only and should not replace professional medical advice. Anyone with symptoms of a kidney infection should seek immediate evaluation from a qualified healthcare professional, as delayed treatment can lead to serious complications
