Kidney stones affect roughly one in 11 Americans, and the pain they cause is often described as the most intense physical experience a person can endure. Most kidney stones pass on their own with fluids and pain management, but certain situations turn a painful nuisance into a genuine medical emergency. Understanding when to go to the ER for kidney stones can help you avoid dangerous complications like kidney infection, urine blockage, and sepsis while also sparing you an unnecessary $3,000-plus ER bill when home management is the right approach. This guide covers the specific warning signs that demand immediate attention. For more on recognizing serious health situations, see our medical conditions guide.
Warning Signs That Require an ER Visit
Not every kidney stone needs emergency care, but several specific scenarios do. The Mayo Clinic and the American Urological Association agree on the following red flags.
When to seek emergency care: Call 911 or go to the nearest emergency room if you have kidney stone pain with a fever over 100.4 degrees Fahrenheit, inability to keep down fluids due to persistent vomiting, pain so severe it does not respond to over-the-counter medication, complete inability to urinate, blood in the urine that is heavy or increasing, or kidney stone symptoms in a person with only one functioning kidney.
Fever With Kidney Stones: The Most Dangerous Combination
A kidney stone combined with a fever is the single most urgent scenario. This combination suggests that the stone is blocking urine flow and an infection is developing behind the obstruction. This condition, called obstructive pyelonephritis or pyonephrosis, can progress to sepsis within hours.
According to a study in the Journal of Urology, infected obstructing kidney stones have a mortality rate of up to 10 percent if treatment is delayed. The treatment is not pain medication or antibiotics alone; it requires emergency drainage of the blocked kidney, either with a ureteral stent or a percutaneous nephrostomy tube.
If you have known or suspected kidney stones and develop a fever, chills, or shaking rigors, go to the ER immediately. Do not wait to see if the fever resolves. The Cleveland Clinic emphasizes that time is critical in preventing septic shock in these cases.
Uncontrollable Pain
Kidney stone pain, called renal colic, occurs in waves as the ureter contracts around the stone. The pain typically starts in the flank (side of the back below the ribs) and radiates toward the groin. It is notoriously severe, and many patients rank it above broken bones, childbirth, and surgical recovery.
If over-the-counter NSAIDs (ibuprofen 800 mg) and acetaminophen together cannot bring your pain to a manageable level, an ER visit is reasonable. The ER can provide IV ketorolac (a powerful NSAID), IV fluids, and opioid pain medication if needed. They can also perform imaging to determine the stone’s size and location, which predicts whether it will pass on its own.
Pain alone is not dangerous in most cases, but uncontrolled pain prevents you from staying hydrated, which slows stone passage. If you cannot drink fluids because the pain triggers vomiting, you need IV hydration to prevent dehydration and kidney injury.
Persistent Vomiting and Dehydration
Nausea and vomiting commonly accompany kidney stone pain because the kidneys and the GI tract share nerve pathways. Occasional vomiting is unpleasant but not dangerous. However, persistent vomiting that prevents you from keeping down any fluids for several hours creates a dangerous cycle.
Without adequate fluid intake, you become dehydrated. Dehydration reduces urine output, which makes it harder for the stone to move through the urinary tract. It also concentrates the urine, increasing the risk of kidney injury. The NIH recommends IV fluid resuscitation for kidney stone patients who cannot maintain oral hydration.
If you have been vomiting for more than a few hours and cannot keep water down, the ER can provide IV fluids, anti-nausea medication, and pain control to break the cycle. For more detail on recognizing kidney stone symptoms, see our article on symptoms of kidney stones.
Signs of Urinary Tract Blockage
A stone that completely blocks the flow of urine from a kidney causes it to swell, a condition called hydronephrosis. If unrelieved, the buildup of pressure can damage the kidney permanently.
Signs of significant obstruction include a complete inability to urinate (rare, as the other kidney usually continues producing urine), pain that shifts from waves to constant severe pressure, decreasing urine output, and increasing flank or abdominal swelling. According to the Mayo Clinic, complete obstruction of a solitary kidney (or both kidneys) is a true urological emergency requiring immediate intervention.
The ER evaluation includes a CT scan to assess the degree of obstruction and the stone’s size and location. Stones larger than 6 to 7 millimeters are unlikely to pass on their own and may require procedural intervention such as lithotripsy or ureteroscopy.
When You Can Safely Manage at Home
Not every kidney stone requires an ER visit. If you have been diagnosed with kidney stones before and recognize the symptoms, and none of the red flags above are present, home management is often appropriate.
Home management strategies include drinking two to three liters of water daily to flush the stone through, taking NSAIDs (ibuprofen 600 to 800 mg every six to eight hours with food) for pain and to reduce ureteral inflammation, using a heating pad on the flank for comfort, and straining urine to catch the stone for analysis.
Your doctor may also prescribe tamsulosin (Flomax), an alpha-blocker that relaxes the ureter muscles and helps stones pass more easily. According to the NIH, medical expulsive therapy with tamsulosin increases the likelihood of spontaneous stone passage, particularly for stones between 5 and 10 millimeters.
You should still follow up with a urologist or your primary care doctor within a few days if you are managing at home. They can confirm the stone’s size with imaging and establish a timeline for when intervention might be needed if the stone doesn’t pass.
What Happens at the ER for Kidney Stones
If you go to the ER, the standard evaluation includes a urine sample to check for blood and signs of infection, blood tests to assess kidney function and look for elevated white blood cells, a CT scan without contrast (the gold standard for detecting kidney stones), IV pain medication and anti-nausea drugs, and IV fluids to restore hydration.
Based on the results, the ER physician may determine the stone is small enough to pass at home and discharge you with prescriptions, call a urologist for emergency stent placement if there is an infected obstructing stone, or admit you if there are signs of sepsis or severe obstruction. The Cleveland Clinic notes that most ER kidney stone visits result in discharge home with follow-up instructions.
Frequently Asked Questions
How do I know if my kidney stone is an emergency?
The three clearest emergency indicators are fever with kidney stone symptoms, inability to keep fluids down for several hours, and pain that is completely unresponsive to over-the-counter medication. Any of these warrants an ER visit. Progressive symptoms like increasing pain, worsening blood in the urine, or decreasing urine output also require prompt evaluation.
Can a kidney stone cause permanent kidney damage?
Yes, if a stone completely blocks a ureter for an extended period, the resulting pressure can cause permanent kidney damage. According to urology research, complete obstruction lasting more than two weeks begins to cause irreversible loss of kidney function. This is why follow-up imaging is important even when you’re managing pain at home.
Should I go to the ER or urgent care for kidney stones?
If you have any red flag symptoms (fever, severe uncontrolled pain, vomiting, inability to urinate), go directly to the ER, which has CT scanning and urological support. For manageable pain without red flags, an urgent care center can provide pain medication and a referral for imaging, which may be sufficient and more cost-effective. However, most urgent care centers cannot perform CT scans on-site.
How long should I wait for a kidney stone to pass before going to the ER?
Stone passage time depends on size. Stones under 4 mm usually pass within one to two weeks. Stones 4 to 6 mm may take two to four weeks. Stones over 6 mm often require intervention. If your pain is manageable and you have no red flag symptoms, waiting with close medical follow-up is reasonable. If your doctor ordered imaging that shows a large stone or worsening hydronephrosis, intervention should not be delayed.
The Bottom Line
Deciding when to go to the ER for kidney stones hinges on three main questions: Do you have a fever? Can you manage the pain and keep fluids down? Is your urine flow normal? If you have a fever with kidney stone symptoms, go to the ER without hesitation, as an infected obstructing stone is a medical emergency that can become life-threatening within hours. If pain is uncontrollable or you cannot stay hydrated, the ER provides the IV medications and fluids you need. For everything else, well-managed home care with close medical follow-up is usually the right approach.