Can Small Kidney Stones Pass Naturally? Yes, many small kidney stones can pass naturally in the urine, especially stones smaller than about 5 mm that are already in the lower part of the ureter. Stones between 5 and 10 mm may pass but are less likely to, and larger stones usually need treatment. Passing a stone can take days to weeks and is often painful. A urologist can confirm the size and position of the stone with tests and advise whether waiting with medicines is safe or whether a procedure is needed.
This guide explains which stones are likely to pass, what helps, how long it may take and the warning signs that need urgent care.
What Is a Kidney Stone?
Kidney stones are hard deposits that form when minerals and salts in the urine, such as calcium, oxalate or uric acid, become concentrated and stick together. A stone may stay in the kidney without symptoms or move into the ureter, the narrow tube that carries urine to the bladder. Most pain occurs when a stone moves into or blocks the ureter. Read more about types of kidney stones.
Which Kidney Stones Can Pass Naturally?
Stone size
Size is the most important factor. As a general guide:
- Under about 5 mm: often pass on their own
- About 5 to 10 mm: may pass, but the chance is lower and it may take longer
- Over 10 mm: rarely pass without treatment
Stone location
Stones that have already moved to the lower ureter, near the bladder, are more likely to pass than stones in the upper ureter or kidney.
Other factors
The shape of the stone, the width of your ureter, previous stone history and whether there is infection or blockage all affect the outcome. This is why each case needs individual assessment.
Symptoms of a Passing Kidney Stone
- Sharp, cramping pain in the side or back, below the ribs
- Pain that comes in waves and may spread to the lower abdomen or groin
- Pain or burning while passing urine
- Pink, red or brown urine
- Frequent urge to pass urine
- Nausea and vomiting
Our article on the first signs of kidney stones covers early symptoms in more detail.
How Is a Kidney Stone Assessed?
Before deciding to wait for a stone to pass, a doctor will usually advise:
- Urine tests to check for blood, infection and crystals
- Blood tests to check kidney function
- Imaging such as ultrasound or a CT scan to measure the stone and see where it is and whether it is blocking urine flow
What Helps a Small Stone Pass?
If your urologist feels it is safe to wait, an approach called watchful waiting or medical expulsive therapy may be advised. It commonly includes:
- Fluids: drinking enough water through the day so that urine is pale, unless your doctor advises otherwise
- Pain relief: medicines prescribed by your doctor to control the pain
- Medicines to relax the ureter: in some cases, to help the stone move
- Staying active: normal activity as comfort allows
- Straining urine: collecting the stone, if it passes, for analysis of its type
- Follow-up imaging: to confirm the stone has passed
Home remedies seen online are not a substitute for medical review. Some can cause harm, especially in people with kidney or heart problems.
How Long Does It Take?
Many small stones pass within a few days to a few weeks. Doctors usually review the situation if a stone has not passed in about four to six weeks, or sooner if symptoms worsen. A stone that stays stuck for a long time can block urine flow and affect kidney function, even if pain settles.
When Is Treatment Needed?
A procedure may be advised when:
- The stone is large or unlikely to pass
- Pain cannot be controlled with medicines
- There is infection along with blockage
- Kidney function is affected
- The stone does not move over time
- You have a single kidney or certain other health conditions
Options include shock wave lithotripsy (ESWL), ureteroscopy, retrograde intrarenal surgery (RIRS) and percutaneous nephrolithotomy (PCNL), depending on the size and site of the stone. Learn more in our post on which size of kidney stone needs surgery and on our kidney stone treatment page.
Warning Signs: Seek Urgent Care
- Fever or chills with stone pain
- Severe pain that does not settle with medicines
- Repeated vomiting and inability to keep fluids down
- Passing very little or no urine
- Stone pain in pregnancy or with a single kidney
Preventing Kidney Stones
- Drink enough fluids through the day, especially in hot weather
- Limit added salt and highly processed foods
- Do not cut out calcium-rich foods unless advised; balanced calcium intake is generally recommended
- Moderate intake of animal protein
- Follow specific diet advice based on your stone type
See also our diet plan for kidney stone prevention.
Frequently Asked Questions
What size of kidney stone can pass naturally?
Stones smaller than about 5 mm often pass on their own, while stones between 5 and 10 mm may pass but are less likely to. Larger stones usually need treatment. Location in the urinary tract and the shape of the stone also matter.
How long does it take for a small kidney stone to pass?
Many small stones pass within a few days to a few weeks. Your doctor may advise a review if the stone has not passed within about four to six weeks, as a stone stuck for long can affect kidney function.
Does drinking more water help pass a kidney stone?
Staying well hydrated increases urine flow and may help a small stone move, unless your doctor has asked you to limit fluids. Very large amounts of water in a short time are not advised. Follow your doctor’s guidance.
What medicines help pass kidney stones?
Doctors may prescribe pain relief and, in some cases, medicines that relax the muscle of the ureter to help a stone pass. These should only be taken on medical advice.
When is a kidney stone an emergency?
Seek urgent care if you have fever or chills with stone pain, severe pain not controlled by medicines, persistent vomiting, very little or no urine, or a stone in a single kidney. Infection with a blocked kidney needs immediate treatment.
How can I prevent kidney stones from coming back?
Drinking enough fluids through the day, limiting excess salt and processed foods, eating a balanced diet and following advice based on your stone type can lower the chance of new stones. A urologist may suggest tests to identify the stone type.
Consult Dr. Irfan Shaikh at Urolife Clinic, Pune
If you have been told you have a small kidney stone, or you have pain that may be stone related, a urology consultation can help you understand whether it is likely to pass and what to watch for. Dr. Irfan Shaikh (MBBS, MS General Surgery, M.Ch. Urology) consults at Urolife Stone and Mens Clinic.
- Address: KD Plaza, 2nd Floor, Above Union Bank, 7 Loves Chowk, Pune, Maharashtra 411042
- Phone: +91 86863 53030