Kidney stones affect roughly one in 11 Americans during their lifetime, and the pain they cause is often described as the most intense physical experience a person can endure. The good news is that most kidney stones pass on their own with fluids and pain management. The critical caveat is that a few specific situations turn a painful nuisance into a genuine medical emergency, and recognizing them quickly can be the difference between an uncomfortable week and a life-threatening infection. Understanding when to go to the ER for kidney stones helps you avoid dangerous complications like kidney infection, urine blockage, and sepsis, while also sparing you an unnecessary emergency-room bill (often several thousand dollars, though estimates vary widely) when home management is the right call. This guide leads with the warning signs that demand immediate attention. For more on recognizing serious health situations, see our medical conditions guide.
Call 911 or go to the nearest emergency room now if you have kidney stone symptoms plus any of the following:
- A fever or chills (possible infected, obstructing stone, which can become life-threatening)
- Pain so severe you cannot bear it or that does not ease at all with over-the-counter medicine
- Vomiting that prevents you from keeping down any fluids
- An inability to urinate, or a sudden drop in how much you are urinating
- Heavy or increasing blood in your urine
- Confusion, dizziness, a racing heart, or clammy skin (possible signs of sepsis)
- Only one working kidney, a kidney transplant, or a known severe obstruction
When in doubt, get evaluated. Do not wait to see whether a fever resolves.
Warning Signs That Require an ER Visit
Not every kidney stone needs emergency care, but several specific scenarios do. The Mayo Clinic and the Urology Care Foundation (the patient-education arm of the American Urological Association) point to the same set of red flags. Seek emergency care right away if you have kidney stone pain together with a fever, an inability to keep down fluids because of persistent vomiting, pain that does not respond to over-the-counter medication, a complete inability to urinate, blood in the urine that is heavy or increasing, or kidney stone symptoms in a person who has only one functioning kidney or a transplanted kidney. Each of these is covered in detail below.
Fever With Kidney Stones: The Most Dangerous Combination
A kidney stone combined with a fever is the single most urgent scenario, and it deserves to be treated as an emergency until a clinician proves otherwise. This combination can mean that the stone is blocking urine flow and an infection is building up behind the obstruction. This condition, sometimes called obstructive pyelonephritis or pyonephrosis, can progress to sepsis and septic shock quickly, in some cases within hours.
Crucially, the treatment for an infected obstructing stone is not pain medication or antibiotics alone. It requires urgent drainage of the blocked kidney, either with a ureteral stent placed by a urologist or a percutaneous nephrostomy tube placed by an interventional radiologist. Antibiotics cannot reach the infected, trapped urine effectively until the pressure is relieved, which is why time matters so much.
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 whether the fever settles on its own. The Cleveland Clinic emphasizes that a stone with signs of infection is a urological emergency, and that prompt drainage and antibiotics are what prevent it from turning into septic shock. If you are ever unsure whether your symptoms qualify, that uncertainty is itself a reason to be seen.
Uncontrollable Pain
Kidney stone pain, called renal colic, tends to come in waves as the ureter contracts around the stone. The pain typically starts in the flank (the 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 standard over-the-counter pain relievers cannot bring your pain down to a tolerable level, an ER visit is reasonable. In the emergency department, clinicians can provide intravenous anti-inflammatory medication, IV fluids, and, when appropriate, stronger prescription pain relief under supervision. Just as importantly, the ER can perform imaging to determine the stone’s size and location, which helps predict whether it is likely to pass on its own. (This article does not provide medication doses; any pain-medicine regimen should come from a clinician or pharmacist who knows your history, kidney function, and other medications.)
Pain by itself is not usually dangerous, but uncontrolled pain prevents you from staying hydrated, which slows stone passage. If the pain triggers vomiting and you cannot drink, you may need IV hydration to prevent dehydration and protect your kidneys.
Persistent Vomiting and Dehydration
Nausea and vomiting commonly accompany kidney stone pain because the kidneys and the gastrointestinal tract share nerve pathways. Occasional vomiting is unpleasant but not dangerous. Persistent vomiting that stops you from keeping down any fluids for several hours, however, 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, and it concentrates the urine in ways that can stress the kidneys. MedlinePlus notes that severe nausea and vomiting are among the symptoms that should prompt a call to your provider or an emergency visit. In the ER, clinicians can give 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 the kidney to swell, a condition called hydronephrosis. If the blockage is not relieved, the buildup of pressure can, over time, cause lasting kidney damage.
Signs of significant obstruction include a complete inability to urinate (which is uncommon when both kidneys work, because the unaffected kidney keeps producing urine), pain that shifts from coming in waves to a constant severe pressure, a noticeable drop in urine output, and increasing flank or abdominal discomfort. According to the Mayo Clinic, complete obstruction of a solitary kidney, or obstruction of both kidneys at once, is a true urological emergency that requires immediate intervention. People with a single functioning kidney or a transplanted kidney should therefore have a lower threshold for seeking care.
The ER evaluation usually includes a CT scan to assess the degree of obstruction along with the stone’s size and location. As a general rule, larger stones are less likely to pass on their own and are more likely to need a procedure such as shock-wave lithotripsy or ureteroscopy, but your urologist will interpret your specific imaging in context.
When You Can Safely Manage at Home
Not every kidney stone requires an ER visit. If you have been diagnosed with kidney stones before, you recognize the symptoms, and none of the red flags above are present, home management is often appropriate, especially with a clinician aware of your situation.
Home management generally centers on staying well hydrated to help flush the stone through, using over-the-counter pain relief as directed by a clinician or pharmacist, applying a heating pad to the flank for comfort, and straining your urine to catch the stone for analysis. Rest and monitoring for any of the emergency warning signs are part of the plan too.
Your doctor may also prescribe tamsulosin (Flomax), an alpha-blocker that relaxes the ureter and can help some stones pass more easily. This approach, known as medical expulsive therapy, is prescribed on a case-by-case basis and is generally considered for certain stones in the mid-size range; whether it is right for you is a decision for your clinician. Telehealth can be a practical way to arrange this kind of non-emergency care and follow-up, as we discuss in our guide to telehealth for kidney stones.
Even when you manage at home, follow up with a urologist or your primary care doctor within a few days. They can confirm the stone’s size with imaging and set a timeline for when intervention might be needed if the stone does not pass. Home management is not the same as ignoring the stone.
What Happens at the ER for Kidney Stones
If you go to the ER, the standard evaluation typically 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 (widely regarded as the most accurate test for detecting kidney stones), IV pain and anti-nausea medication, 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 and follow-up instructions, involve a urologist for urgent stent placement or drainage if there is an infected obstructing stone, or admit you if there are signs of sepsis or severe obstruction. The Cleveland Clinic notes that many ER kidney stone visits end in discharge home with instructions, but the purpose of the visit is precisely to identify the minority of cases that are dangerous.
Frequently Asked Questions
How do I know if my kidney stone is an emergency?
The clearest emergency indicators are fever or chills with kidney stone symptoms, an inability to keep fluids down for several hours, pain that is completely unresponsive to over-the-counter medication, and an inability to urinate. Any of these warrants an ER visit. Progressive symptoms, such as steadily increasing pain, worsening blood in the urine, or decreasing urine output, also call for prompt evaluation. Fever is the one you should never wait out.
Can a kidney stone cause permanent kidney damage?
Yes. If a stone completely blocks a ureter for a prolonged period, the resulting back-pressure can damage the affected kidney, and an untreated infected obstruction can cause harm much faster. This is why follow-up imaging matters even when you are managing pain at home, and why fever with a stone is treated urgently rather than watched.
Should I go to the ER or urgent care for kidney stones?
If you have any red-flag symptoms (fever, severe uncontrolled pain, persistent vomiting, or an inability to urinate), go directly to the ER, which has CT scanning and urology support. For manageable pain without red flags, an urgent care center can sometimes provide pain relief and arrange imaging, which may be enough and more affordable. Bear in mind that many urgent care centers cannot perform a CT scan on-site, so anything that looks like a possible infection or obstruction belongs in the ER.
How long should I wait for a kidney stone to pass before going to the ER?
Passage time depends largely on the stone’s size, and smaller stones tend to pass faster than larger ones, though timelines vary from person to person. If your pain is manageable and you have no red-flag symptoms, waiting with close medical follow-up is reasonable. If imaging shows a large stone or worsening hydronephrosis, or if any emergency sign appears, do not wait. Let your clinician’s read of your specific imaging guide the timeline rather than a fixed number of days.
The Bottom Line
Deciding when to go to the ER for kidney stones comes down to three 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, because an infected obstructing stone is a medical emergency that can become life-threatening within hours and needs urgent drainage, not antibiotics alone. 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.
TL;DR: Most kidney stones pass at home with hydration, pain control, and follow-up. Treat fever or chills with stone pain, uncontrollable pain, vomiting that stops you keeping fluids down, or an inability to urinate as an emergency: go to the ER or call 911. An infected, obstructing stone can turn into sepsis within hours and needs urgent drainage.
Medical disclaimer: This article is for general education only and is not medical advice, diagnosis, or treatment. It does not include medication doses. Always consult a qualified clinician about your situation, and in an emergency call 911 or go to the nearest emergency department.