Kidney infection (pyelonephritis): signs, tests and treatment
A kidney infection usually starts as a urine infection in the bladder that travels up to one or both kidneys. It causes fever and pain in the side, and it needs antibiotics the same day.
It is more common, and more serious, in people with diabetes. Our laboratory runs urine tests and culture 24 hours a day, and patients who need IV antibiotics can be admitted in the same building.
Pain in the side or back, just below the ribs, on one or both sides
Burning while passing urine, passing urine often, or a sudden urge to pass it
Cloudy, foul-smelling or blood-stained urine
Nausea, vomiting or not wanting to eat
In older people and in people with diabetes the signs can be less clear. Sometimes the only clues are feeling generally unwell, sugars that suddenly run high, or new confusion in an elderly parent.
Bladder infection or kidney infection?
Bladder infection (cystitis)
Kidney infection (pyelonephritis)
Fever
Little or none
Usually, often with chills
Pain
Low in the tummy, above the pubic bone
In the side or back, below the ribs
Vomiting
Uncommon
Common
How urgent
See a doctor within a day or two
See a doctor the same day
Fever with urine symptoms should be treated as a kidney infection until a doctor says otherwise.
Why diabetes makes it more serious
More common and more severe
High sugar weakens the body's defence against bacteria. Kidney infections happen more often and are more likely to spread into the blood.
Rare but dangerous forms
A gas-forming infection inside the kidney, or a pus collection (abscess), occurs mostly in people with diabetes. These need a scan and sometimes a drain, and they are why we do not ignore a fever that is not settling.
Sugars go up
Infection pushes blood sugar up, and high sugar makes the infection harder to clear. Both are treated together. Insulin is sometimes needed for a few days, even in people normally on tablets.
Your diabetes medicines
If you are vomiting, not eating or very unwell, some medicines (such as dapagliflozin, empagliflozin and metformin) may need to be paused for a few days. Do not stop them on your own: follow our sick day rules and ask your doctor.
Tests
Urine routine (CUE): shows pus cells and signs of infection, usually within hours
Urine culture and sensitivity: grows the bacteria and shows which antibiotics work. Give the sample before the first antibiotic dose. The result takes about 2 to 3 days, so treatment starts before it is ready and is changed if needed. ₹1,100 at Caspian Diagnostic Centre
Blood tests: blood count, kidney function (creatinine), sugar, and sometimes a blood culture
Ultrasound of the kidneys: looks for a stone or a blockage. It is needed when the infection is severe, keeps coming back, or is not getting better
CT scan: when the fever has not settled after 2 to 3 days of the right antibiotic, or a gas-forming infection or abscess is suspected
All the urine and blood tests are done 24 hours a day by Caspian Diagnostic Centre, in the same building. A clean sample matters: our staff will show you how to collect a midstream urine sample, and our sample collection sheet explains it too.
Treatment: tablets at home, or IV in hospital?
Tablets at home are usually fine if
you can eat, drink and keep tablets down
your blood pressure is normal and you are not drowsy
your sugars are under control
you are not pregnant
IV antibiotics in hospital are safer if
you are vomiting or cannot drink enough
you have high fever with chills, or low blood pressure
your sugars are high, or ketones are present
you are elderly and frail, have kidney disease, or have had a recent kidney procedure
tablets have not helped in 2 to 3 days
What to do during treatment
Finish the full antibiotic course, usually 7 to 14 days, even when you feel better after two or three days
Drink enough water to pass pale urine, unless your doctor has limited your fluids for heart failure or kidney disease
Check your sugar more often than usual, and tell us if it stays above 250 mg/dL
Paracetamol helps the fever and pain. Avoid painkillers such as diclofenac and ibuprofen, which can harm kidneys that are already under strain
Come back if the fever has not settled in 2 to 3 days. That usually means a blockage, an abscess, or bacteria that need a different antibiotic
Do not start an antibiotic from an old prescription or a chemist's suggestion. It can hide the infection and spoil the culture result.
What we do at Caspian, and where we send you
Done here
Consultation, and urine and blood tests at any hour
Admission for IV antibiotics and fluids, with a cardiac monitor on every bed and a doctor in the building 24 hours
Sugar control by the diabetes team while you are admitted
Ultrasound for admitted patients, most of the time in our own building
Medicines from Caspian Pharmacy, open 24 hours
Arranged elsewhere
CT scan: Red Hills Diagnostic Centre
A stone or blockage that needs a stent or drain: Dr Hidayat Ullah, urologist, TX Hospital, Mehdipatnam
Intensive care, dialysis or surgery: Saradamba Institute of Medical Sciences (SIMS), Vidyanagar
Kidney infection in pregnancy: Dr Humera Sultana, obstetrician, Crescent Hospital, Mehdipatnam
Bed charges are on our price list: a ward bed is ₹3,500 a day and a cubicle ₹4,500 a day, bed charge only. Medicines and tests are billed separately.
When not to wait
Call 108 or go to the nearest hospital with an ICU straight away if there is:
confusion, drowsiness, or difficulty waking
fainting, a very fast heartbeat, or fast breathing
very little or no urine for 12 hours
vomiting that stops you keeping any fluids down
a sugar above 300 mg/dL with ketones, or with vomiting and tummy pain
Caspian Healthcare has no emergency department and no ICU. We treat kidney infections that are not critical, and transfer patients who become critically ill.
If it keeps coming back
Two or more kidney infections, or frequent bladder infections, need a proper look for the reason: high sugars, a kidney stone, a bladder that does not empty fully, an enlarged prostate in men, or changes after menopause in women. We review your sugars and medicines, arrange the scans, and refer to a urologist when needed.
Common questions
Is a kidney infection contagious?
No. It cannot be passed to family members.
Can it damage my kidneys permanently?
In adults, a single kidney infection treated on time rarely leaves lasting damage. Repeated infections, a blockage left untreated, or delay in treatment can scar the kidney. This is why the full course and a review matter.
Does cranberry juice treat it?
No. A kidney infection needs antibiotics. Cranberry products have not been shown to treat an infection that is already present.
Do I need a urine test after the course?
Not usually, if your symptoms have gone. A repeat culture is done if symptoms continue or return, or if you are pregnant.
When can I go back to work?
Most people feel well enough within a few days of the fever settling. Rest until the fever has gone and you are eating normally.
Book a visit
Bring any urine or blood reports you already have, the name of any antibiotic you have taken in the last few days, and the list of every medicine you take.
Medically reviewed by Dr. Khizer Hussain Junaidy, Diabetologist & Bariatric Physician, Telangana State Medical Council 04937. Last reviewed 11 October 2026. General information for patients of Caspian Healthcare: your own doctor's advice comes first.