How Long Does It Take to Pass a Kidney Stone?

Learn how kidney stone size and location affect passage time, supportive treatments, and signs to seek urgent medical attention.

By Medha deb

Created on Sep 26, 2025

Learn how kidney stone size and location affect passage time, supportive treatments, and signs to seek urgent medical attention.

Passing a kidney stone can be an intensely uncomfortable experience, and many people want to know how soon they’ll find relief. The time it takes to pass a kidney stone depends on factors such as stone size and location, as well as your overall health and hydration status. This article covers why kidney stones form, the expected timeline for passing them, tips for speeding up passage, and when you should seek medical attention.

What Is a Kidney Stone?

Kidney stones are solid deposits made of minerals and salts that form in the kidneys when these substances become highly concentrated in the urine. The most common minerals involved are calcium, oxalate, and uric acid. Small stones may pass through the urinary tract unnoticed, while larger stones can become lodged in the ureter, leading to significant pain and other complications.

Common Risk Factors for Developing Kidney Stones

High dietary intake of protein or salt
Low fluid intake / dehydration
Excess intake of vitamin D
Metabolic disorders (such as gout)
Obesity
Inflammatory bowel diseases
Family history of kidney stones
Male sex (men are at higher risk)

Typical Symptoms

Intense pain in the back or side, often starting suddenly
Blood in the urine (hematuria)
Frequent urge to urinate
Pain while urinating
Cloudy or foul-smelling urine
Reduced urine output

The two most important factors in determining how quickly you’ll pass a kidney stone are size and location of the stone within the urinary system.

Timeline by Stone Size

Stone Size	Chance of Passing Naturally	Typical Passage Time
< 4 mm	80%	~31 days
4–6 mm	60%	~45 days
> 6 mm	20%	Up to 12 months, or needs surgery

Small stones (less than 4 mm) typically pass within a month, often with minimal intervention. Stones between 4 mm and 6 mm may also pass, but it can take longer—up to about a month and a half. Stones larger than 6 mm are much less likely to pass on their own and may persist for up to a year, often requiring medical or surgical intervention to remove them.

How Stone Location Affects Passage

While stone size is the main determinant, the location within the urinary tract also matters:

Stones closer to the bladder (the lower end of the ureter) are more likely to pass naturally. Studies show a success rate as high as 79% for these stones.
Stones closer to the kidney (upper ureter) are less likely to pass on their own. About 48% of these stones may pass without medical intervention.

Other Factors Influencing Passage

Hydration status: Drinking enough fluids, especially water, helps move the stone along and can speed up passage.
Pre-existing medical conditions: Conditions that alter urine composition may affect stone movement.
Shape and composition of the stone: Smooth stones tend to pass more quickly than jagged or irregular ones.

Speeding Up the Passage of a Kidney Stone

Getting a kidney stone to pass as quickly as possible is a common goal, especially to alleviate pain and discomfort. Here are the most effective ways to potentially speed up the process:

Hydrate aggressively: Aim for enough fluids to produce at least 2.5 liters of urine per day. Water is best; avoid sugary sodas and limit caffeine.
Pain management: Use over-the-counter medications, such as ibuprofen or acetaminophen, as advised by your doctor, to control pain during passage.
Alpha blockers: These prescription medications, such as tamsulosin, can help relax the muscles in the ureter, making it easier for the stone to pass.
Physical activity: Gentle movement or walking can sometimes help move the stone along, though excessive exercise is not recommended during severe pain episodes.
Monitor urine: Use a strainer to catch the stone when it passes, as your doctor may want to analyze it for its composition.

When to Seek Medical Attention

While many kidney stones pass on their own, certain symptoms or circumstances require urgent medical evaluation.

Call a doctor right away if you experience:

Severe or worsening pain, especially if it does not respond to medication
Fever or chills (possible sign of infection)
Nausea or vomiting that prevents keeping fluids down
Blood in the urine (hematuria) that is persistent or heavy
Difficulty or inability to urinate
Symptoms of urinary tract infection (burning, foul-smelling urine)

Prompt medical attention is especially important if you have only one kidney, a history of kidney disease, diabetes, or other serious health conditions.

Treatment Options for Large or Stubborn Stones

If a stone is too large to pass, causes infection, blocks urine flow, or is accompanied by severe symptoms, a healthcare professional may recommend one or more of the following treatments:

Shock wave lithotripsy (SWL): Uses focused sound waves to break the stone into smaller, passable fragments.
Ureteroscopy: A long, thin tube is inserted into the urinary tract to remove or break up the stone.
Percutaneous nephrolithotomy: In more severe cases, a small incision is made in the back to directly remove the stone from the kidney.
Medications: Can include both pain relievers and alpha blockers to help the stone move.

Prevention: Reducing the Risk of Future Stones

If you have passed a kidney stone, you are at higher risk for developing others in the future. Consider adopting these preventive steps:

Drink plenty of water daily to keep urine diluted
Limit protein and sodium intake, if advised by your doctor
Increase citrus fruits (lemon, lime) as citrate can inhibit stone formation
Follow any specific dietary or medication instructions based on the stone type
Maintain a healthy weight

Frequently Asked Questions (FAQs)

Q: How can I tell if my kidney stone is passing?

A: Signs that a stone is moving include pain that radiates from the back to the groin, changes in urine appearance (cloudy, bloody, foul-smelling), and increased urge or frequency of urination. Sudden relief from pain may indicate the stone has passed into the bladder.

Q: Does passing a kidney stone hurt?

A: Passing a kidney stone can be extremely painful, particularly as it moves through the ureter, but pain usually subsides once the stone reaches the bladder and exits the body.

Q: What can I do to make a stone pass more quickly?

A: Drink plenty of water to help flush the stone out. Some medications, such as alpha blockers, may help the muscles of the ureter relax and allow the stone to pass more easily. Always follow your doctor’s advice.

Q: When is surgery necessary?

A: Surgery or other interventions are typically recommended when the stone is too large (>6 mm), fails to pass after several weeks, causes infection, or if there is significant blockage or uncontrolled pain.

Q: Can kidney stones come back?

A: Yes. A history of kidney stones greatly increases your risk of developing more stones in the future, especially without lifestyle or dietary changes.

Key Takeaways

Most kidney stones smaller than 4 mm will pass naturally in about a month.
Stones between 4 mm and 6 mm take longer to pass, with about 60% doing so on their own in roughly 45 days.
Larger stones (>6 mm) usually require medical or surgical intervention.
Stay well hydrated, manage symptoms, and seek medical help for severe or unusual symptoms.
Adopting preventive measures can reduce your risk of future kidney stones.

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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