Signs and symptoms of a kidney infection may include:
- Back, side (flank) or groin pain
- Abdominal pain
- Frequent urination
- Strong, persistent urge to urinate
- Burning sensation or pain when urinating
- Pus or blood in your urine (hematuria)
- Urine that smells bad or is cloudy
When to see a doctor
Make an appointment with your doctor if you have any signs or symptoms that worry you. Also make an appointment if you’re being treated for a urinary tract infection but your signs and symptoms aren’t improving.
Severe kidney infection can lead to life-threatening complications. Seek immediate medical attention if you experience typical kidney infection symptoms combined with bloody urine or nausea and vomiting.
Kidney infection typically occurs when bacteria enter your urinary tract through the tube that carries urine from your body (urethra) and begin to multiply.
Bacteria from an infection elsewhere in your body also can spread through your bloodstream to your kidneys. Kidney infection is unusual through this route, but it can happen — for instance, if you have an artificial joint or heart valve that becomes infected.
Rarely, kidney infection results after kidney surgery.