How Fast Can a Kidney Infection Become Fatal?

What Is a Kidney Infection?

A kidney infection, or pyelonephritis, is a type of urinary tract infection (UTI) that starts in the bladder and travels up to the kidneys. While bladder infections are common and usually not serious, kidney infections involve vital organs that filter blood and maintain fluid balance, making them more serious. 

Typical symptoms include fever, chills, fatigue, nausea, and pain in the back or side (flank pain). These symptoms can appear quickly and progress fast without treatment.

Find out how to differentiate kidney pain from back pain.

Can a Kidney Infection Be Fatal?

Yes, but only if it’s left untreated or not recognized early. The biggest danger is urosepsis, a life-threatening complication where the infection spreads into the bloodstream. This can lead to septic shock, a condition that damages organs and requires intensive care.

Fortunately, this is rare in people who seek medical care quickly. Early treatment with antibiotics greatly reduces the risk of severe complications.

Who Is Most at Risk?

Some groups are more likely to experience severe infections or complications like sepsis:

• Older adults, especially over 65
• People with diabetes
• Pregnant women
• Immunocompromised individuals (e.g., those on chemotherapy, with HIV, or post-transplant)
• People with kidney stones or urinary tract obstructions
• Patients using catheters or recovering from urologic procedures

How Fast Can Kidney Infection Become Serious?

Kidney infections can become dangerous in as little as 24 to 72 hours, especially in vulnerable individuals. Sepsis starts when an infection spreads and the body can’t control its response. This strong reaction can damage organs and become life-threatening.

Early antibiotic treatment drastically slows or prevents this progression. But in older or high-risk patients, even mild symptoms can escalate quickly. 

Warning Signs You Need Emergency Help Now

If you experience the following symptoms, it’s time to seek emergency care:

• Fever over 38.3°C (101°F)
• Vomiting or signs of dehydration
• Fast heart rate or confusion
• Clammy skin or low blood pressure
• Worsening back or side pain

These signs may indicate that the infection has reached your bloodstream, and immediate treatment is necessary.

What Happens If Kidney Infection Goes Untreated?

Without antibiotics or supportive care, a kidney infection can lead to:

• Urosepsis
• Kidney damage or failure
• Prolonged hospitalization or ICU stay
• Death in rare advanced cases

Untreated urosepsis has a mortality rate as high as 30-40%, depending on patient age and underlying conditions. Early intervention greatly reduces this risk.

How Doctors Confirm a Kidney Infection

When you visit a doctor with a suspected kidney infection, here’s what to expect:

Laboratory Tests

• Urinalysis: To check for white blood cells, bacteria, and nitrites
• Urine culture: Identifies the exact bacteria causing the infection and helps tailor antibiotic treatment
• Blood tests: May show elevated white blood cell count or abnormal kidney function (creatinine, BUN)
• Blood cultures: Done if sepsis is suspected, to detect bacteria in the bloodstream

Imaging Tests

• Ultrasound: Often used first to check for kidney swelling, abscesses, or obstruction
• CT scan: Provides a detailed view of the kidneys; used if symptoms are severe, if the patient is not improving, or if a structural abnormality is suspected
• X-rays or MRI: Rare, but considered in special situations

Imaging is most useful in complicated infections, especially if stones, abscesses, or anatomical issues are suspected.

How to Treat and Prevent Kidney Infections

Treatment

Treatment usually includes oral or IV antibiotics based on the severity. Supportive care like IV fluids and pain management may also be needed. Completing the full course of antibiotics is crucial to avoid recurrence.

Other key steps:

• Stay hydrated
• Rest until fever and pain subside
• Return for follow-up testing to ensure the infection is cleared

Can You Prevent a Kidney Infection?

Yes! These habits can reduce your risk:

• Drink plenty of water
• Treat UTIs early
• Urinate after sex
• Wipe front to back (for women)
• Avoid delaying urination
• Manage conditions like diabetes or enlarged prostate