The pain hits suddenly — a sharp, cramping sensation in your side or lower back that radiates toward your groin. If you’ve never experienced it before, you might think something is seriously wrong with an internal organ. In many cases, you’d be right to be concerned. The symptoms of kidney stones can range from barely noticeable (for tiny stones that pass silently) to excruciating pain that sends over 500,000 Americans to emergency rooms each year, according to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Recognizing these symptoms early — and knowing when to seek urgent care — matters for your health and your recovery. Our medical conditions guide covers this and other conditions that affect millions of Americans.
When to seek emergency care: Call 911 or go to the nearest emergency room if you experience kidney stone pain with a fever over 101.3F (38.5C), inability to keep down fluids due to persistent vomiting, blood in your urine accompanied by extreme pain, inability to urinate, or pain so severe that you cannot find a comfortable position. These may indicate an infected kidney stone or urinary obstruction — both of which require immediate medical attention.
What Are Kidney Stones?
Kidney stones (nephrolithiasis) are hard deposits of minerals and salts that form inside the kidneys. They develop when urine becomes concentrated, allowing minerals like calcium, oxalate, uric acid, and phosphate to crystallize and stick together. Stones range in size from a grain of sand to a golf ball, though most are small enough to pass through the urinary tract — painfully, but without surgical intervention.
About 1 in 10 Americans will develop a kidney stone at some point, and the prevalence has been increasing over the past two decades. Men are nearly twice as likely to develop stones as women, though the gap has narrowed. According to the American Urological Association, the recurrence rate is high: about 50% of people who have one kidney stone will develop another within 5 to 10 years without preventive measures.
The Classic Symptoms of Kidney Stones
Not all kidney stones cause symptoms. Small stones may pass through the urinary tract without any noticeable pain. Symptoms typically begin when a stone moves from the kidney into the ureter — the narrow tube connecting the kidney to the bladder. This is when the real trouble starts.
Severe Flank and Back Pain (Renal Colic)
Renal colic — the hallmark kidney stone symptom — is often described as one of the most intense pains a person can experience. It typically begins suddenly in the flank (the area between the ribs and hip on one side) and radiates toward the lower abdomen and groin. The pain comes in waves, intensifying over 20 to 60 minutes and then partially subsiding before building again. This pattern occurs because the ureter contracts in spasms as it tries to push the stone through.
The pain location can shift as the stone moves. A stone high in the ureter causes flank and upper back pain. As it moves lower, pain migrates toward the lower abdomen, groin, and even the inner thigh or testicle in men or labia in women. Research published in the European Urology journal rates kidney stone pain as comparable to or exceeding childbirth pain in severity.
Blood in the Urine (Hematuria)
Visible blood in the urine — ranging from pink to red to brown — occurs in about 80% to 90% of kidney stone patients. The stone irritates and scrapes the lining of the urinary tract as it passes. Even microscopic amounts of blood (detected only on a urine test) are significant. Hematuria without pain can indicate a stone that hasn’t yet caused obstruction, or it can suggest other urological conditions that warrant evaluation.
Nausea and Vomiting
Up to 50% of kidney stone patients experience nausea, and many vomit. This happens because the kidneys and the gastrointestinal tract share nerve pathways. Severe pain also triggers nausea via the autonomic nervous system. Persistent vomiting is concerning because it can lead to dehydration, which worsens stone-related complications and makes it harder for the body to flush the stone naturally.
Urinary Symptoms
As a stone approaches the bladder or lodges near the ureterovesical junction (where the ureter enters the bladder), urinary symptoms intensify. Frequent urination, urgency (feeling like you need to go immediately), burning or pain during urination, and difficulty urinating are all common. These symptoms can mimic a urinary tract infection, and in fact, kidney stones can cause secondary UTIs when they obstruct urine flow and allow bacteria to accumulate.
Less Common Symptoms
Fever and chills accompanying kidney stone pain are red flags that suggest infection — an infected obstructing stone is a urological emergency. Cloudy or foul-smelling urine may also indicate infection. Restlessness and an inability to find a comfortable position are characteristic of renal colic; unlike many other types of abdominal pain, kidney stone patients often pace or shift constantly rather than lying still.
Referred pain to the testicle (in men) or vulvar area (in women) occurs when stones irritate nerves near the lower ureter. This can be confusing diagnostically, particularly when the referred pain is more prominent than the flank pain. Some patients experience only lower abdominal or groin pain without the classic flank component, which can lead to initial misdiagnosis.
How Kidney Stones Are Diagnosed
When you present with symptoms suggestive of kidney stones, doctors typically order a non-contrast CT scan of the abdomen and pelvis — the gold standard for detecting stones, with a sensitivity above 95%. Urinalysis checks for blood, infection, and crystals in the urine. Blood tests assess kidney function and check for elevated white blood cell counts that might suggest infection.
Ultrasound is an alternative to CT in certain situations — particularly for pregnant patients, children, and those trying to minimize radiation exposure. It’s less sensitive for small stones but can detect hydronephrosis (swelling of the kidney from urine backup), which indirectly confirms obstruction. A plain abdominal X-ray (KUB) can detect calcium-containing stones but misses uric acid and other radiolucent stones. If you’re concerned about imaging costs, our guide on CT scan pricing covers what to expect.
Treatment Options and When Stones Require Intervention
Most kidney stones under 5mm pass on their own within 1 to 2 weeks with conservative management: hydration (2 to 3 liters of water daily), pain medication (NSAIDs like ibuprofen are first-line), and alpha-blocker medication (tamsulosin) to relax the ureter and facilitate passage. Stones 5mm to 10mm may pass spontaneously but have a lower success rate and may require intervention if pain is unmanageable or the stone doesn’t progress.
Stones larger than 10mm rarely pass on their own and usually require procedural treatment. Options include extracorporeal shock wave lithotripsy (ESWL), which uses sound waves to break stones into passable fragments, and ureteroscopy with laser lithotripsy, where a thin scope is passed through the urethra and bladder to reach and fragment the stone. For very large stones (over 2cm), percutaneous nephrolithotomy (PCNL) — a minimally invasive surgical approach through the back — may be necessary.
According to the Mayo Clinic, the treatment approach depends on stone size, location, composition, and the patient’s symptoms and overall health. Emergency intervention is required when a stone causes complete urinary obstruction, uncontrollable pain, persistent vomiting preventing oral hydration, or signs of infection (fever, chills).
Prevention: Reducing Your Risk of Recurrence
Since kidney stones recur in about half of patients within a decade, prevention is critical. The single most effective preventive measure is increasing fluid intake to produce at least 2.5 liters of urine per day — the American Urological Association guidelines emphasize this as the cornerstone of stone prevention.
Dietary modifications depend on stone type. For calcium oxalate stones (the most common, at about 80%), reducing sodium intake, maintaining adequate calcium through food (not supplements), limiting oxalate-rich foods (spinach, rhubarb, nuts, chocolate), and consuming adequate citrus (lemon juice) can help. For uric acid stones, reducing animal protein and purine-rich foods and potentially alkalinizing the urine with potassium citrate are recommended. Your doctor may order a 24-hour urine collection to guide specific dietary and medical recommendations.
Frequently Asked Questions
What does kidney stone pain feel like?
Kidney stone pain (renal colic) typically feels like a sudden, severe cramping pain in the flank or lower back that radiates toward the groin. It comes in waves, intensifying for 20 to 60 minutes before partially easing. Many patients describe it as the worst pain they’ve ever experienced — comparable to or exceeding childbirth.
Can kidney stones cause pain without blood in urine?
Yes. While 80% to 90% of kidney stone patients have blood in their urine (hematuria), some do not — especially if the stone is causing obstruction without significant mucosal irritation. The absence of blood in the urine does not rule out kidney stones.
How long does it take to pass a kidney stone?
Small stones (under 5mm) typically pass within 1 to 2 weeks. Stones 5mm to 7mm may take 2 to 4 weeks. Stones larger than 7mm have a low chance of passing spontaneously and often require medical intervention. Factors like hydration, stone location, and individual anatomy affect passage time.
Can kidney stones cause permanent kidney damage?
Prolonged obstruction from a kidney stone can damage the kidney if not treated. An obstructing stone that completely blocks urine flow can cause hydronephrosis and, over weeks to months, permanent loss of kidney function on the affected side. This is why stones causing complete obstruction require urgent treatment. Brief obstruction from a passing stone rarely causes lasting damage.
When should I go to the ER for kidney stones?
Seek emergency care if you have kidney stone symptoms with fever (possible infected stone), inability to keep fluids down, inability to urinate, pain so severe that over-the-counter medication doesn’t help, or if you have only one kidney. An infected obstructing stone is a urological emergency requiring immediate drainage.
Risk Factors You Can and Cannot Control
Understanding your risk factors helps with both prevention and symptom recognition. Dehydration is the single most modifiable risk factor — people who consistently drink less than 2 liters of fluid daily have significantly higher stone incidence. Diet plays a major role: high sodium intake (above 2,300mg daily) increases calcium excretion in the urine, and diets high in animal protein raise uric acid levels. Obesity is independently associated with kidney stone risk — a NIH-funded study found that people with a BMI over 30 have 1.5 to 2 times the kidney stone risk of those with a normal BMI.
Family history is a strong non-modifiable risk factor. If a first-degree relative (parent or sibling) has had kidney stones, your risk is 2 to 3 times higher than the general population. Certain medical conditions also predispose you to stones: hyperparathyroidism, gout, chronic urinary tract infections, inflammatory bowel disease (especially Crohn’s disease), and type 2 diabetes. Medications including calcium-based antacids, topiramate, and certain diuretics can increase stone formation in susceptible individuals.
Geographic location and climate matter as well. People living in the “Stone Belt” of the southeastern United States have higher incidence rates, likely related to higher temperatures causing more sweating and concentrated urine. Stone prevalence peaks during summer months across all regions.
What to Do Next
If you’re experiencing symptoms consistent with kidney stones — especially severe flank pain, blood in urine, or pain with fever — contact your healthcare provider or go to urgent care promptly. For red-flag symptoms (fever above 101.3F, persistent vomiting, inability to urinate, or extreme unmanageable pain), go directly to the emergency room without delay. An infected obstructing kidney stone is one of the true urological emergencies that can become life-threatening if not treated within hours. Early evaluation means earlier pain relief, appropriate monitoring, and intervention if the stone won’t pass on its own. If you’ve already been diagnosed with stones and are managing treatment costs, our healthcare costs guide can help you plan for imaging and treatment expenses.