Kidney stones are hard deposits made of minerals and salts that form inside your kidneys. Passing a kidney stone can be quite painful. But how long it takes to pass a kidney stone depends on several factors.
What is a kidney stone?
A kidney stone is a hard mass that forms in one or both kidneys from minerals in the urine, like calcium, oxalate, and phosphate. When the urine becomes concentrated, these minerals can stick together and crystallize into a stone.
Kidney stones vary in size. They can be as small as a grain of sand or as large as a golf ball. Some kidney stones stay in the kidney, while others travel down the urinary tract. Smaller stones may pass on their own, while larger ones may get stuck and block urine flow, causing severe pain.
What causes kidney stones?
There are several factors that can increase your risk of developing kidney stones:
- Dehydration – Not drinking enough fluids
- Diet high in protein, sodium, and oxalate
- Obesity
- Digestive disorders like Crohn’s disease
- Family history of kidney stones
- Certain medications
Kidney stones are more common in men than women. Risk increases between ages 20 and 50. Once you have one kidney stone, your chances of having another go up.
Symptoms of kidney stones
When a stone moves through your urinary tract, symptoms may include:
- Severe pain in the back, side, lower abdomen, or groin
- Pain that comes and goes in waves
- Pain with urination
- Cloudy or foul-smelling urine
- Nausea and vomiting
- Feeling an urgent need to urinate
- Blood in the urine
The pain often starts suddenly when a stone moves in the urinary tract. This pain can be excruciating. Some people say it’s worse than childbirth or broken bones. You may have pain on one side based on where in the urinary tract the stone is located.
How long does it take to pass a kidney stone?
Passing a kidney stone can take hours, days, weeks, or even months depending on several factors:
- Size of the stone – Smaller stones tend to pass quicker than larger ones.
- Location of the stone – Stones in the ureters take longer to pass since the ureters are narrow.
- Prior stone history – Subsequent stones may pass quicker in those who have already passed them before.
- Medications – Medications can help relax the ureter to allow stones to pass sooner.
- Treatments – Some methods like lithotripsy can break up stones to speed up passage.
On average, studies show:
- Stones less than 5mm – 70-80% pass within 4 weeks
- Stones 5-7mm – 20-57% pass within 4 weeks
- Stones 7-9mm – Very low rates of passage
So smaller kidney stones less than 5mm have a good chance of passing within 1-2 weeks. Medium stones between 5-7mm may take up to 4 weeks. Large stones over 7mm are unlikely to pass without additional treatments.
Factors that affect how long it takes to pass a kidney stone
Stone size
Stone size is the most important factor affecting passage time. The larger the stone, the longer it will likely take to pass:
- Stones less than 5mm – Tend to pass within 1-2 weeks
- Stones 5-7mm – May take up to 4 weeks to pass
- Stones over 7mm – Unlikely to pass without additional treatment
Larger stones have a harder time moving through the narrow ureters between the kidneys and bladder. Studies show stones less than 5mm have a nearly 80% chance of passing within 4 weeks, while stones over 7mm have very low odds of passing spontaneously.
Stone location
Where the stone is located also impacts how long it takes to pass:
- Kidney – Stones in the kidney causes less symptoms. Passage time averages 20-45 days.
- Ureter – Stones in the ureter cause the most pain. Passage time averages 10-21 days.
- Bladder – Stones in the bladder rarely obstruct. Passage is quick within 1-2 days.
Stones located in the narrow ureters typically cause the most symptoms but have a shorter passage time. Stones that reach the bladder pass within 1-2 days since the bladder has a larger capacity.
Prior stone history
People who have passed a kidney stone before may pass subsequent stones quicker. Research shows that stones pass faster in patients with a history of prior stones.
It’s believed that passing an initial stone causes some dilation or widening of the ureter. This makes it easier for future stones to pass through the ureter, therefore decreasing passage time.
Medications
Certain medications can help relax the ureter and speed up stone passage:
- Alpha blockers – Help relax ureteral muscles
- Calcium channel blockers – Prevent ureter spasms
- Steroids – Decrease swelling around the stone
These drugs are often used for larger stones greater than 5mm to improve the chances of successful passage. They work by opening up the ureters to provide a wider path for stones to pass through.
Treatments
Procedures like lithotripsy use sound waves to break up larger stones into smaller pieces. This allows the smaller fragments to pass out of the body faster. Treatment options include:
- Lithotripsy – Breaks up stones using sound waves
- Ureteroscopy – Removes stones using a small scope
- Laser surgery – Breaks up or removes stones with laser
These methods speed the passage of stone fragments by days to weeks compared to waiting for a larger intact stone to pass. Breaking stones into smaller pieces helps them pass through the urinary system quicker.
How to speed up kidney stone passage
There are some home remedies and tips that may help speed up kidney stone passage by a few days or weeks:
- Drink plenty of fluids – 3-4 liters daily helps flush out stones
- Take over-the-counter pain relievers – To manage discomfort from passing stones
- Try lemon juice – Some citrates may help break up small stones
- Take warm baths – Can help soothe pain during stone passage
- Perform light exercise – May help progress stone movement
While these methods may provide some benefit, they work best for small stones under 5mm. Larger stones usually require prescription medications or procedures for the quickest passage.
When to see a doctor
You should seek medical care if you experience:
- Severe pain or vomiting that prevents normal activity
- Fever and chills suggesting infection
- No improvement in symptoms within 6 weeks
- Inability to pass urine due to obstruction
Getting evaluated by a urologist helps determine the stone’s size and location. They can prescribe medications or recommend procedures if a stone is unlikely to pass within a reasonable timeframe.
Diagnosis of kidney stones
Kidney stones are diagnosed through imaging and lab tests such as:
- CT scan – Best test to visualize stones
- Ultrasound – Uses soundwaves to detect stones
- X-ray – Helps detect stones except those made of uric acid
- Urine analysis – Checks for blood or crystals
Based on results, your doctor can determine stone size, exact location, and treatment options. Blood tests help assess any underlying condition that may be causing recurrent kidney stones.
Treatment options for kidney stones
Several treatment options are available to help remove stones or speed up passage:
Medications
- Alpha blockers to relax the ureter
- Pain relievers for discomfort
- Antibiotics if infection is present
Procedures
- Extracorporeal shock wave lithotripsy – Breaks up stones with sound waves
- Ureteroscopy – Removes stones with small camera
- Percutaneous nephrolithotomy – Extracts stones through a small incision
Surgery
- Ureteroscopy or laser lithotripsy
- Open surgery in rare cases where stones are very large
The decision depends on stone size, location, your health, and preference. Smaller stones under 5mm can often be managed with medications and waiting for spontaneous passage.
Preventing kidney stones
Some ways to help prevent future kidney stones include:
- Drink plenty of fluids – At least 2-3 liters daily
- Eat a balanced diet – Lower sodium, oxalate and protein
- Take prescribed medications – Such as thiazide diuretics
- Avoid certain supplements – Calcium, vitamin C, vitamin D
Making dietary and lifestyle changes according to your doctor’s advice can help reduce your chances of forming another stone. Staying hydrated is key to prevent the minerals in urine from crystalizing.
Conclusion
How long it takes to pass a kidney stone depends on several factors, especially stone size and location. Smaller stones less than 5mm may pass within 1-2 weeks. Larger stones over 7mm are unlikely to pass without treatment. Medications and procedures can help speed up stone passage by a few days to weeks.
Seeking prompt medical attention is crucial if you are experiencing severe symptoms or inability to pass urine. To help prevent future kidney stones, be sure to drink plenty of fluids daily and make diet and lifestyle changes as advised by your doctor.
