How Long Does It Take to Pass a Kidney Stone?

Explore the timeline for passing kidney stones, factors affecting duration, symptoms, and treatment options for a smoother recovery.

By Medha deb

Created on Sep 26, 2025

Explore the timeline for passing kidney stones, factors affecting duration, symptoms, and treatment options for a smoother recovery.

Kidney stones are solid crystalline masses that form in the urinary tract when certain minerals and chemicals aggregate rather than being expelled in urine. The main concern for most people who develop a kidney stone is how long it will take to pass through the urinary system, causing pain and potential complications. The answer is not universal: the passage time depends on several key factors, including stone size and location, as well as a person’s overall health and hydration levels.

What Are Kidney Stones?

Kidney stones are mineral deposits made from chemicals such as calcium, oxalate, uric acid, and cystine, which can form crystals in the kidneys. These stones can vary in size, shape, and chemical composition. While some kidney stones are tiny enough to exit the body without any symptoms, larger stones may lodge in the urinary tract, causing severe pain and requiring medical intervention.

Common components: calcium, uric acid, oxalate, cystine
Risk factors: dehydration, high protein or salt intake, certain metabolic disorders, genetics, obesity, and some medications

How Do Kidney Stones Form?

Certain conditions lead to high concentrations of stone-forming substances in the urine, such as:

Dehydration
Diet high in protein, sodium, or sugar
Metabolic or digestive disease (e.g., gout, inflammatory bowel disease)
Obesity or rapid weight loss
Family history of kidney stones

When urine lacks enough fluids to dissolve these minerals, they crystallize and stick together, forming stones of varying sizes and types.

The time it takes to pass a kidney stone can range from a few days to over a year, depending on its size and location in the urinary tract. Let’s break down these primary factors:

Size of the Kidney Stone

Stone Size	Chance of Passing Naturally	Average Time to Pass
<4 mm	~80%	About 31 days
4–6 mm	~60%	About 45 days
>6 mm	<20%	Up to 12 months (often needs intervention)

Generally, the smaller the stone, the faster it passes:

Stones less than 4 mm typically pass on their own—sometimes within one to two weeks, but on average, about a month.
Stones 4–6 mm may take 45 days, and many will require some form of treatment.
Stones larger than 6 mm usually require medical removal, since only about a fifth pass naturally even over a year.

Location of the Kidney Stone

The location of the stone in the urinary tract also impacts how easily and quickly it will pass:

Stones at the lower end of the ureter (closer to the bladder) are more likely to pass by themselves (about 79%).
Stones in the upper part of the ureter (closer to the kidney) have a lower pass rate (about 48%) without treatment.

The closer a stone is to the bladder, the less distance it has to travel, and the more likely it is to pass without intervention.

Other Factors Affecting Passage Time

Hydration levels—higher fluid intake helps stones pass more quickly.
Urinary tract anatomy and function.
Presence of infection or other medical conditions.
Stone composition (calcium, uric acid, etc.).

Symptoms of Passing a Kidney Stone

Kidney stones may or may not cause noticeable symptoms. Common symptoms as stones move through the urinary tract include:

Sudden and severe pain in the back or sides (flank pain)
Pain radiating toward the lower abdomen or groin
Painful urination
Blood in urine (hematuria)
Cloudy or foul-smelling urine
Frequent urge to urinate
Passing only small amounts of urine or difficulty urinating
Nausea or vomiting
Fever and chills (may indicate infection)

If a stone lodges and blocks the urinary tract, it can cause a backup of urine, swelling, and infection, escalating symptoms and requiring urgent medical attention.

Stages of Passing a Kidney Stone

Formation in the Kidney: Crystals gather and grow into stones inside the kidney.
Movement into the Ureter: The stone moves into the narrow tubes connecting the kidneys to the bladder, often causing waves of intense pain as it travels.
Reaching the Bladder: Pain may reduce when the stone reaches the bladder, though it may cause bladder irritation and urinary frequency.
Exiting via Urethra: The stone is expelled out of the body during urination, usually with less pain than earlier phases.

Ways to Speed Up Passing a Kidney Stone

While kidney stones must traverse the urinary tract at the body’s natural pace, certain strategies can encourage a faster, safer passage and reduce symptoms:

Hydration: Drink plenty of fluids, especially water, to help flush the stone along.
Physical activity: Gentle movement, such as walking, may assist movement of the stone.
Pain management: Use over-the-counter pain medication like acetaminophen or ibuprofen, unless contraindicated by your doctor.
Medical expulsive therapy: Some doctors may prescribe alpha-blocker medications to relax the muscles of the ureter, easing passage of the stone.

Important: Do not delay medical attention if pain is severe, you develop a fever, can’t urinate, or see significant blood in the urine.

When To Call Your Doctor

If you experience any of the following symptoms, seek medical care:

Persistent or worsening severe pain
Fever or chills
Bloody, cloudy, or foul-smelling urine
Trouble urinating, inability to urinate, or pain during urination
Nausea and vomiting that prevent you from keeping fluids down
Symptoms persisting beyond a reasonable timeframe (more than four to six weeks) without improvement

These may indicate complications like infection, kidney damage, or obstruction that require rapid assessment and intervention.

Medical Treatment Options for Kidney Stones

While many kidney stones pass on their own, some require further intervention. Treatment depends on stone size, type, and location, as well as symptom severity. Options include:

Medication: Pain relievers, alpha-blockers, and medications to dissolve certain types of stones.
Shock wave lithotripsy (SWL): Uses focused sound waves to break stones into small pieces that can be passed more easily.
Ureteroscopy: A thin scope is inserted into the urethra and bladder to retrieve or break up stones.
Percutaneous nephrolithotomy: Minimally invasive surgery for very large or complicated stones.

Preventing Future Kidney Stones

Maintain optimal hydration—aim for at least 8-12 cups of water daily, or as recommended by your doctor.
Reduce high-oxalate foods (spinach, rhubarb, nuts) if you have a history of calcium oxalate stones.
Limit sodium, animal protein, and added sugars.
Consider citrate-rich foods (lemons, limes, oranges) to help inhibit stone formation.
Monitor medications and consult your doctor for individualized advice.

Frequently Asked Questions (FAQs)

Small stones (<4 mm) can pass in about 31 days or less, while larger stones may take 45 days or more. Stones larger than 6 mm frequently require intervention and can take up to a year to pass naturally if at all.

What symptoms should I watch for when passing a kidney stone?

Look for severe back or abdominal pain, pain with urination, blood in the urine, and persistent nausea or vomiting. Fever or chills signal a possible infection, which requires urgent care.

Can I speed up the passage of a kidney stone?

Drinking plenty of fluids may help, as can prescribed medications that relax the ureter. Pain medicine can make passing stones more tolerable. Always ask your healthcare provider before making changes to your treatment plan.

When should I seek medical attention?

Seek immediate medical help if you develop fever, severe or unrelenting pain, cannot urinate, have persistent vomiting, or see significant blood in your urine.

What are the risks of untreated kidney stones?

Untreated kidney stones may cause recurring pain, urinary obstruction, kidney infection, and eventually kidney damage. Prompt management reduces these risks.

Can lifestyle changes help prevent kidney stones?

Yes, maintaining hydration and a balanced diet, watching sodium and animal protein intake, and avoiding excessive supplementation can lower your risk. For some, medication or dietary adjustments targeting the stone type may be recommended.

Key Takeaways

Kidney stones vary in how long they take to pass, largely determined by their size and location.
Small stones often pass naturally, with adequate fluid intake supporting a faster process.
Larger stones or those causing significant symptoms often require medical or surgical intervention.
Not all kidney stones have clear causes, but high fluid intake, dietary changes, and managing risk factors can help prevent recurrence.
Monitor for warning signs and seek medical attention as needed to avoid complications.

References

Author

medha deb

Medha Deb is an editor with a master's degree in Applied Linguistics from the University of Hyderabad. She believes that her qualification has helped her develop a deep understanding of language and its application in various contexts.

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