All You Need to Know About Kidney Infections
By Dr. Aniket Hase +2 more
Medically reviewed by Dr. Aniket Hase
Last updated: Jul 16, 2025 Published on: Jul 16, 2025
Click to rate this article!
[Total: 0 Avg: 0]
Get,
to manage your symptom
Get your,
4 Cr+ families
benefitted
OTP sent to 9988776655
You’ve successfully subscribed to receive
doctor-approved tips on
Whatsapp
Get ready to feel your best.
Register to Avail the Offer
Send OTPBy continuing, you agree with our Privacy Policy and Terms and Conditions
Hi There,
Sign up on PharmEasy now!!
Trusted by 4 crore+ families
OTP sent to 9988776655
You have unlocked 25% off on medicines
Code: NU25
By Dr. Aniket Hase +2 more
Table of Contents
A urinary tract infection (UTI) is the multiplication and proliferation of bacteria in the urinary tract. It can occur in any part of the tract like urethra(urethritis), bladder (cystitis), prostate (in males) (prostatitis) and even spread to the kidneys (pyelonephritis). UTIs are one of the most common infectious disease world-wide in community as well as health care setting1. UTI can occur from neonates to elderly. Approximately 50-60% of women report at least one attack of UTI in their lifetime. In men and children, UTI is comparatively less common and is usually associated with structural and functional abnormality of urinary tract needing further investigations2.
Kidney infection or Pyelonephritis, usually presenting with symptoms such as fever, chills, nausea, and pain3, can even cause septicaemia leading to death, particularly in elderly individuals4. Recurrent chronic pyelonephritis can also lead to kidney damage, hence it is important to detect and treat pyelonephritis early5. The right diagnosis and timely care can make all the difference in your recovery.
A kidney infection, also known as pyelonephritis, is a serious infection that causes inflammation in the kidneys. It typically starts as a lower urinary tract infection (UTI) and ascends from the bladder to the kidneys. Common bacteria like E. coli are often responsible, and currently many of these bacteria are becoming drug resistant.
Pyelonephritis can present with fever, back or flank pain, nausea, and frequent or painful urination. In some cases, the infection can spread through the bloodstream and may be associated with obstructions like kidney stones. If not treated promptly, it can lead to kidney damage, sepsis, or even death.
Pyelonephritis can be acute or chronic, with chronic cases leading to long-term scarring and kidney dysfunction3. Understanding its causes and early symptoms is crucial, as prompt treatment can prevent complications and preserve kidney health.
Kidney infections, or acute pyelonephritis, are a widespread complication of urinary tract infections, with an estimated 10.5 to 25.9 million cases occurring globally each year6.
In India, 60 to 70 adult cases may be seen per year at a single tertiary care hospital. While females are more likely to be affected according to some research, males can also be significantly impacted, especially in older age groups. About three out of four patients have diabetes, and infections are often complicated, requiring hospital care, especially when drug-resistant bacteria are involved7.
The human urinary tract and urine are normally sterile. However, when pathogens invade the urinary tract and spread up to the kidneys, kidney infection or pyelonephritis can occur. While pathogens can enter through blood stream too, retrograde spread through the urinary tract is typically the most common route for kidney infections3.
Kidney infections are most often caused by bacteria, with E. coli being the commonest pathogen followed by K. pneumoniae. The bacteria usually spread from the gut and skin to the urinary tract and reach the kidneys. Certain fungal infections like candida may also sometimes cause kidney infections, particularly in patients with diabetes, ICU stays, or indwelling catheters. Viruses are a less common cause and usually affect those with weakened immunity3,5.
There are various host factors that prevent the invasion of pathogens in the urinary tract. However, some underlying conditions (discussed later) can disrupt these defences and increase the likelihood of getting kidney infections.
A kidney infection usually happens when bacteria or, less commonly, viruses or fungi reach the kidneys. Here are some of the most commonly identified mechanisms of infection of kidney:
| Cause | Mechanism |
| Ascending Infection | Bacteria travel up from bladder through ureters (commonest route) |
| Vesicoureteral Reflux (VUR) | Congenital reflux of urine into the kidneys in children |
| Hematogenous Spread | Bacteraemia in debilitated or immunocompromised individuals |
Table 1: Common Pathways and Mechanisms for Kidney Infections3
Certain individuals are more likely to develop kidney infections due to underlying health or lifestyle factors.
Here are some of the most commonly identified risk factors3:
Pyelonephritis symptoms can vary widely, especially across age groups.
Common Symptoms3:
Symptoms in Children and Older Adults3:
Other Signs to Watch For3:
If you notice these signs, it’s important to seek medical help quickly.
Urinary tract infections (UTIs) and kidney infections affect different parts of the urinary system and can feel quite different. Knowing the key symptoms (see Table 2) can help you understand when it’s more serious and time to seek medical care.
| What’s Affected | Uncomplicated UTI8 | Kidney Infection (Acute Pyelonephritis)3 |
| Part of Body | Lower urinary tract – bladder and urethra | Upper urinary tract – kidneys |
| Common Symptoms | Burning while urination, frequent urge to urinate, pain in the lower stomach (suprapubic pain), sometimes blood in urine | Fever, flank pain (pain in your side or back), nausea, vomiting, anorexia |
| Serious Symptoms | Usually, no fever or severe illness | Often includes fever (over 103°F), chills, blood pressure or sepsis signs in severe cases |
| How It Feels to the Touch | Often normal; mild tenderness above the pubic bone (in some cases) | Pain when touching the side or back, near the kidneys; tenderness above the pubic bone may also occur |
| How Fast Symptoms Start | Gradual, over a couple of days | Rapidly over hours to a day |
| Older Adults & Children | Older adults may show non-specific signs like altered mental status | Elderly and children may present atypically with fever, altered sensorium, or feeding issues |
| How It’s Treated | Usually with oral antibiotics at home | Requires prompt, often more aggressive treatment; may need IV antibiotics or hospitalization |
Table 2: Comparison of UTI and Kidney Infection
Kidney infections can sometimes lead to serious health issues, especially if not treated properly or in time. Here are some of the known complications3:
To diagnose a kidney infection, healthcare professionals consider the patient’s medical history, symptoms, physical examination findings, and the results of laboratory and imaging tests. They may ask whether the patient has any conditions that increase the risk of kidney infections. In men, a digital rectal examination (DRE) may be performed to check for prostate enlargement, which can contribute to urinary tract infections9.
Laboratory tests typically include9:
Imaging tests may be used in certain cases and include9:
Kidney infections require prompt medical treatment to prevent complications10.
Pyelonephritis treatment typically involves antibiotics, supportive care, and, in some cases, hospitalization. Here are the most commonly used treatment methods:
Commonly used antibiotic groups include11:
In pregnant women, fluoroquinolones should not be used. Instead, doctors prefer beta-lactam antibiotics, along with regular checks to make sure the baby is safe.
Consult your doctor and do not self-medicate, early administration of antibiotics is important in cases of pyelonephritis. It is important to take all prescribed antibiotics, even if symptoms improve early. Not completing the full course can lead to antibiotic resistance, making future infections harder to treat10.
Here are some helpful tips to ease symptoms at home:
Supportive care at home can help relieve symptoms and aid recovery but always remember to use them as adjunct and never as alternate to prescribed medical treatment3.
Kidney infections often begin as bladder infections. Maintaining good daily habits and hygiene can reduce the risk10.
Here are some simple ways to help prevent kidney infections:
Kidney infections can become serious if not treated early. It’s important to recognize warning signs and seek medical attention when needed.
See a doctor right away if you notice3:
Watch for special signs in certain groups3:
It’s also important to get medical help if:
Prompt treatment can prevent serious complications like kidney damage or bloodstream infections.
Kidney infections, or pyelonephritis, occur when bacteria reach the kidneys, often starting from a lower urinary tract infection. They can cause fever, back pain, and nausea, and may become serious if left untreated. Risk factors include urinary obstruction, diabetes, pregnancy, and delayed treatment of UTIs. Diagnosis involves lab tests and imaging, while treatment usually includes antibiotics, pain relief, and in some cases, hospital care or surgical procedures to relieve obstruction.
Despite their severity, kidney infections are highly treatable with early medical attention. Timely diagnosis, completing prescribed antibiotics, staying hydrated, and following preventive hygiene can help ensure full recovery and lower the risk of recurrence. Early recognition and treatment are essential for a full recovery.
Yes. About 80% of people with uncomplicated UTI (lower urinary tract) can be treated at home with oral antibiotics, pain relievers, and rest. Your doctor can suggest the appropriate treatment for you. However, in complicated cases, hospital care may be needed3.
While most cases resolve well, severe infections, especially with sepsis or kidney abscess can be life-threatening, particularly in high-risk people like elderly diabetics. In such cases, the risk of death can be as high as 25%3.
Pregnant women face higher risks of premature delivery, kidney injury, and complications like serious infection or even foetal loss. Prompt treatment is critical for both mother and baby3.
You should be more cautious if you’re over 65, diabetic, have kidney problems, or use a catheter. These increase your risk of severe complications and poor outcomes3.
Yes. Recurrent infections may signal an underlying problem like kidney stones or anatomical abnormalities. If infections return soon after treatment, imaging, and specialist evaluation are advised3.
Cranberry contains proanthocyanidins that may stop bacteria from sticking to the urinary tract lining, helping prevent UTIs that can lead to kidney infections. That is they can be useful for prevention, not treatment13. However, research is still limited for this and it’s best to consult your doctor before resorting to any natural remedies.
Disclaimer: The information provided here is for educational/awareness purposes only and is not intended to be a substitute for medical treatment by a healthcare professional and should not be relied upon to diagnose or treat any medical condition. The reader should consult a registered medical practitioner to determine the appropriateness of the information and before consuming any medication. PharmEasy does not provide any guarantee or warranty (express or implied) regarding the accuracy, adequacy, completeness, legality, reliability or usefulness of the information; and disclaims any liability arising thereof
Leave your comment...
Comments