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Published on: 2/27/2026
Severe kidney pain with fever, chills, or urinary symptoms may be pyelonephritis, a dangerous kidney infection that can progress to sepsis or kidney damage; seek urgent medical evaluation now, and go to the ER for high fever with shaking chills, severe vomiting, confusion, dizziness, or fainting.
There are several factors to consider, including who is at higher risk, which tests confirm it, how antibiotics and timing affect recovery, and when imaging or hospitalization is needed; see the complete, medically approved next steps below.
Severe kidney pain is not something to ignore. If you're experiencing sharp pain in your back or side — especially with fever, chills, or urinary symptoms — one possible cause is pyelonephritis, a serious kidney infection that requires prompt medical attention.
Pyelonephritis is a type of urinary tract infection (UTI) that has spread from the bladder to one or both kidneys. While many bladder infections are mild and easily treated, pyelonephritis is more serious because the kidneys play a vital role in filtering waste and maintaining fluid and electrolyte balance.
Understanding the signs, risks, and medically recommended next steps can help you act quickly and protect your health.
Pyelonephritis is a bacterial infection of the kidney. It usually begins as a lower urinary tract infection (like cystitis) and travels upward through the ureters to the kidneys.
The most common cause is Escherichia coli (E. coli) — bacteria that normally live in the digestive tract but can enter the urinary system.
There are two main types:
Acute pyelonephritis is considered a medical emergency in many cases because it can progress rapidly.
Symptoms often develop quickly and can feel more intense than a typical bladder infection.
Common signs include:
In older adults, symptoms may be less obvious and can include:
In children, symptoms may include:
If you're experiencing these symptoms and want to understand your risk level before contacting a healthcare provider, you can use a free AI-powered Acute Pyelonephritis symptom checker to help assess whether your symptoms align with this serious kidney infection.
However, online tools are not a substitute for medical care — especially if symptoms are severe.
Pyelonephritis is not just a "bad UTI." The kidneys are highly vascular organs, meaning infection can spread into the bloodstream.
Without prompt treatment, complications can include:
Most people recover fully with timely treatment. The key is early diagnosis and appropriate antibiotics.
Anyone can develop pyelonephritis, but certain factors increase risk:
If you fall into a high-risk group, it's especially important to seek care quickly if symptoms develop.
If you suspect pyelonephritis, do not delay care.
Go to:
Seek emergency care immediately if you have:
These could signal sepsis.
A healthcare provider may perform:
Imaging is more likely if:
Antibiotics are the main treatment for pyelonephritis.
Treatment may include:
Common treatment duration:
It's critical to:
Stopping antibiotics early increases the risk of recurrence and resistance.
In addition to antibiotics:
Do not rely on home remedies alone. Cranberry juice or supplements do not treat kidney infections.
Call a doctor immediately if you experience:
Pyelonephritis can worsen quickly. Acting early significantly lowers complication risk.
The good news: Most people recover fully with appropriate treatment.
You may feel better within a few days of starting antibiotics, but fatigue can last longer. Kidney damage is uncommon when treatment is started early.
Follow-up may include:
If you experience frequent UTIs, speak with a healthcare provider about prevention strategies.
While not all cases are preventable, you can lower your risk by:
If you've had pyelonephritis before, speak to your doctor about whether further evaluation is needed.
Severe kidney pain is not something to "wait out." Pyelonephritis is a serious kidney infection that requires medical treatment. The condition is treatable, and most people recover fully — but delays can lead to dangerous complications.
If you're experiencing concerning symptoms and want immediate guidance on whether they could indicate a kidney infection, consider using this free Acute Pyelonephritis symptom checker before reaching out to your healthcare provider.
Most importantly, speak to a doctor immediately if you have high fever, severe pain, vomiting, confusion, or feel suddenly worse. Kidney infections can become life-threatening if untreated.
Prompt medical care makes all the difference.
If something feels severe, unusual, or rapidly worsening — don't wait. Seek care and speak to a qualified healthcare professional about anything that could be serious or life threatening.
(References)
* Al-Ghailani N, Zaki N. Acute pyelonephritis in adults. Semin Nephrol. 2022 Mar;42(2):129-142. doi: 10.1016/j.semnephrol.2022.03.003. PMID: 35149306.
* Stankiewicz L, Hryhorczuk Z, Domański L. Management of Acute Pyelonephritis in Adults: A Narrative Review. J Clin Med. 2023 Jan 17;12(2):778. doi: 10.3390/jcm12020778. PMID: 36671040; PMCID: PMC9861616.
* Stankiewicz W, Hryhorczuk Z, Domański L. Severe Acute Pyelonephritis: Clinical Aspects and Prognostic Factors. Medicina (Kaunas). 2021 Jan 25;57(2):100. doi: 10.3390/medicina57020100. PMID: 33504107; PMCID: PMC7910903.
* Grabe M. Imaging in pyelonephritis. Curr Opin Urol. 2021 Jul 1;31(4):259-265. doi: 10.1097/MOU.0000000000000889. PMID: 33791338.
* Koutra E, Christaki E, Giamarellos-Bourboulis EJ, Giamarellou H. Antimicrobial Resistance in Acute Pyelonephritis: A Global Review. Microorganisms. 2023 Mar 15;11(3):739. doi: 10.3390/microorganisms11030739. PMID: 36968032; PMCID: PMC10057053.
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