Kidney Stones: Causes, Symptoms, Treatment, and Prevention

What Are Kidney Stones?

Kidney stones are solid, pebble-like deposits that form in one or both kidneys when certain minerals and other substances become highly concentrated in urine.

The medical terms include:

• Nephrolithiasis: stones located in the kidney
• Urolithiasis: stones located anywhere in the urinary tract
• Ureterolithiasis: a stone located in a ureter
• Renal calculus: another term for a kidney stone

A stone may be as small as a grain of sand or grow much larger. Very small stones may remain unnoticed or pass without significant discomfort.

Symptoms often begin when a stone:

• Moves from the kidney into a ureter
• Blocks normal urine flow
• Causes pressure above the blockage
• Scrapes or irritates the urinary tract
• Occurs together with a urinary infection

Kidney stones and chronic kidney disease are different conditions, although obstruction, infection, or repeated stone complications may affect kidney health.

For broader kidney-function guidance, read How to Improve Kidney Function Safely: Daily Kidney Care.

What Are the Main Types of Kidney Stones?

Most patient guidance groups kidney stones into four major categories. Calcium stones are the most common category and include calcium oxalate and calcium phosphate stones.

Calcium Oxalate Stones

Calcium oxalate is a common stone composition. It does not mean that all calcium-rich foods should be removed. Calcium eaten with meals can bind oxalate in the digestive tract and reduce the amount absorbed.

Calcium Phosphate Stones

Calcium phosphate stones may occur with higher urine pH or selected metabolic conditions. Prevention should be based on blood and urine findings rather than automatically adding alkalizing products.

Uric Acid Stones

Uric acid stones are more likely to form in persistently acidic urine. Unlike most calcium stones, some uric acid stones can dissolve with clinician-directed urine alkalization.

Struvite Stones

Struvite stones are linked to certain urinary infections and may grow quickly. Diet or cranberry products do not replace infection treatment or urological management.

Cystine Stones

Cystine stones occur in people with cystinuria, a rare inherited condition. They usually require specialist follow-up and a more intensive prevention plan.

What Causes Kidney Stones?

Kidney stones form when urine contains more stone-forming material than the available fluid and natural inhibitors can keep dissolved.

Risk factors may include:

• Low urine volume
• Hot weather or heavy sweating
• Previous kidney stones
• A family history of stones
• High sodium intake
• High intake of selected animal proteins
• Low dietary calcium in some calcium oxalate stone formers
• Certain bowel diseases or intestinal surgery
• Obesity, diabetes, insulin resistance, or gout
• Recurrent urinary infections
• Hyperparathyroidism or high blood calcium
• Cystinuria and other inherited disorders
• Structural urinary-tract differences
• Certain medicines and supplements
• Prolonged immobility in selected situations

Does Family History Matter?

A family history can increase risk, but it does not make stones inevitable.

Family patterns may reflect:

• Inherited urine chemistry
• Cystinuria or another genetic disorder
• Shared dietary habits
• Shared climate and fluid habits
• Similar metabolic risk factors

Can Medicines Cause Stones?

Some medicines can contribute directly to crystals or change urine chemistry.

Examples may include selected:

• Antiviral medicines
• Antiseizure medicines
• Diuretics
• Antibiotics
• Calcium or vitamin supplements
• Weight-loss or laxative products

Do not stop a prescription medicine independently. Ask the prescriber or pharmacist whether it affects stone risk.

What Are the First Symptoms of a Kidney Stone?

Some kidney stones cause no symptoms. Pain often begins when a stone moves into a ureter, obstructs urine flow, or irritates the urinary tract.

Possible symptoms include:

• Sudden, severe pain in the side or back
• Pain below the ribs
• Pain moving toward the lower abdomen or groin
• Pain that comes in waves
• Nausea
• Vomiting
• Pink, red, or brown urine
• Blood detected only through urine testing
• Frequent or urgent urination
• Pain or burning while urinating
• Cloudy or bad-smelling urine
• Difficulty urinating
• Passing only a small amount of urine
• Fever or chills when infection is present

What Is Renal Colic?

Renal colic is severe pain caused by obstruction and muscular contractions as the urinary tract attempts to move urine and the stone past the blockage.

The pain may rise and fall in intensity because the ureter contracts in waves.

Can Kidney Stones Cause Blood in Urine?

Yes. A stone may irritate the lining of the kidney, ureter, bladder, or urethra.

Blood may be:

• Visible as pink, red, or brown urine
• Present only on a urine dipstick
• Detected through laboratory microscopy

Visible blood in urine should be medically assessed because stones are not the only possible cause.

Where Is Kidney-Stone Pain Located?

Pain location cannot reliably identify the exact stone position without imaging.

How Are Kidney Stones Diagnosed?

Evaluation may include:

• A description of the pain and symptoms
• Previous stone history
• Family history
• A physical examination
• Urine testing
• Blood testing
• Imaging
• Analysis of a passed or removed stone

Urine Tests

Urine testing may look for:

• Blood
• White blood cells
• Bacteria
• Crystals
• Urine pH
• Other abnormalities

A urine culture may be required when infection is suspected.

Blood Tests

Blood tests may assess:

• Kidney function
• Serum creatinine
• Calcium
• Uric acid
• Electrolytes
• Markers of infection or inflammation

CT and Ultrasound

Imaging recommendations vary by age, pregnancy status, healthcare system, and clinical situation.

NICE recommends urgent low-dose non-contrast CT within 24 hours for adults with suspected renal colic, while ultrasound is recommended first during pregnancy and for children and young people. The 2026 European Association of Urology guideline uses ultrasound as the primary diagnostic imaging tool and uses non-contrast CT to confirm the diagnosis after initial ultrasound assessment when appropriate.

Both approaches reflect the same principle: imaging should confirm the diagnosis, identify the stone's size and location, assess obstruction, and balance diagnostic accuracy against radiation exposure.

Why Is Follow-Up Imaging Important?

Pain improving does not always prove that the stone has passed.

Follow-up may be required to confirm:

• Stone passage
• Resolution of obstruction
• Recovery of kidney drainage
• Whether a procedure is still needed

What May Help a Kidney Stone Pass Safely?

No home technique can guarantee fast kidney-stone passage. Passage depends on stone size, ureter location, anatomy, symptoms, kidney function, and whether infection or obstruction is present.

For a selected small stone without infection, severe kidney impairment, or another complication, care may include:

• Medical assessment
• Clinician-approved pain medicine
• Anti-nausea medicine
• Appropriate oral fluids
• An alpha-blocker in selected cases
• A urine strainer to collect the stone
• Follow-up imaging or urology review

Should You Force Large Amounts of Water?

No. Forced high-volume drinking during acute renal colic does not guarantee faster passage and may worsen discomfort, especially when urine flow is obstructed or vomiting prevents normal hydration.

Do not force large volumes of water if you:

• Are repeatedly vomiting
• Cannot keep fluids down
• Have severe uncontrolled pain
• Have reduced urine output
• Have heart failure
• Have advanced kidney disease
• Have a prescribed fluid restriction

Hospital fluids may be needed when vomiting or dehydration prevents safe oral intake.

Can Walking Help?

Light activity may be continued if it feels comfortable, but walking has not been proven to guarantee faster stone passage.

Stop and seek advice if activity causes:

• Worsening pain
• Dizziness
• Faintness
• Vomiting
• Weakness

Should You Strain the Urine?

A clinician may recommend urinating through a stone strainer.

Collecting the stone allows laboratory analysis, which can guide prevention.

How Do Stone Size and Location Affect Treatment?

Smaller stones generally have a better chance of passing than larger stones, but size alone does not determine the outcome.

Other factors include:

• Whether the stone is in the kidney or ureter
• How far it has moved down the ureter
• Urinary-tract anatomy
• Swelling around the stone
• Infection
• Pain and vomiting
• Kidney function
• Pregnancy
• Previous surgery or urinary reconstruction

Do not use an online size chart to decide that medical follow-up is unnecessary.

Which Pain Medicines Are Used for Kidney Stones?

Acute renal colic can be extremely painful. Current 2026 European Association of Urology guidance recommends a nonsteroidal anti-inflammatory drug, or NSAID, as the first drug choice when it is medically suitable. NICE also recommends an NSAID first line for suspected renal colic.

NICE recommends intravenous paracetamol when NSAIDs are contraindicated or have not provided enough relief, with opioids considered when both options are unsuitable or insufficient. Local emergency protocols differ, so medication choice should be individualized.

When May NSAIDs Be Unsuitable?

NSAIDs such as ibuprofen, naproxen, diclofenac, or ketorolac may be unsafe or require extra caution with:

• acute kidney injury or significantly reduced kidney function
• dehydration
• stomach ulcers or gastrointestinal bleeding
• selected cardiovascular conditions
• pregnancy
• blood-thinning or interacting medicines

Do not combine multiple products containing the same active ingredient. If pain remains severe despite appropriate treatment, urgent reassessment may be needed rather than repeatedly increasing medicine at home.

When Are Alpha-Blockers Such as Tamsulosin Used?

Alpha-blockers are sometimes used as medical expulsive therapy for selected ureteral stones, but they are not a universal treatment for every kidney stone.

The 2026 European Association of Urology guideline reports the greatest benefit for distal ureteral stones larger than 5 mm and recommends offering an alpha-blocker as an option for distal ureteral stones about 5 to 10 mm when conservative management is appropriate. The EAU notes that this use is off label.

NICE uses a somewhat broader recommendation and says to consider alpha-blockers for distal ureteric stones under 10 mm. This difference is one reason the decision should be made by the treating clinician rather than from an online size chart.

Medical expulsive therapy should be stopped and reassessed if complications develop, such as infection, refractory pain, or worsening kidney function.

Possible Tamsulosin Side Effects

• dizziness or light-headedness
• lower blood pressure
• faintness
• headache
• nasal congestion
• ejaculation changes

Use tamsulosin only when prescribed or specifically advised for your situation.

Do Lemon Water or Natural Remedies Help Kidney Stones?

Natural products should be separated into:

• Measures that may support long-term prevention
• Products with uncertain evidence
• Claims that should not replace treatment

Can Lemon Water Prevent Kidney Stones?

Lemon and other citrus drinks contain citrate. Citrate can bind calcium and may reduce crystal formation in selected stone formers.

The benefit depends on:

• Stone type
• Urine citrate
• Urine pH
• The amount consumed
• Added sugar
• Kidney function
• Other medical conditions

Lemon water does not reliably dissolve an obstructing calcium stone or guarantee stone passage.

Prescribed potassium citrate provides a controlled treatment and should not be replaced with an unmeasured home drink.

Does Apple Cider Vinegar Treat Kidney Stones?

There is not enough reliable clinical evidence to recommend apple cider vinegar as a treatment to dissolve or speed the passage of kidney stones.

Concentrated vinegar may:

• Irritate the throat and stomach
• Worsen reflux
• Damage tooth enamel
• Lower potassium
• Interact with medicines

What About Chanca Piedra?

Chanca piedra is promoted as a traditional “stone breaker,” but evidence is not strong enough to use it as a substitute for established evaluation or treatment, and commercial products vary in composition and purity.

Its interactions, pregnancy safety, kidney effects, and appropriate dose are not sufficiently established.

Do not use it instead of imaging, pain management, infection treatment, or urological follow-up.

Does Kidney Bean Broth Dissolve Stones?

There is no good clinical evidence that kidney-bean pod broth dissolves a stone or makes it pass.

Kidney beans may be eaten as food when compatible with your nutrition and medical needs, but the strained broth is not a kidney-stone treatment.

Do Herbal Diuretics Flush Out Stones?

Herbal diuretics do not reliably remove an obstructing stone.

They may also cause:

• Dehydration
• Electrolyte changes
• Medicine interactions
• Delayed medical treatment

What Medical Procedures Remove Kidney Stones?

A urologist considers:

• Stone size
• Stone location
• Stone density and composition
• Urinary anatomy
• Obstruction
• Infection
• Kidney function
• Pregnancy
• Blood-thinning medicines
• Previous procedures
• Patient preferences

Shock Wave Lithotripsy

Shock wave lithotripsy, sometimes called SWL or ESWL, directs shock waves toward the stone to break it into smaller fragments.

The fragments then pass through urine.

Suitability depends on stone size, location, density, body anatomy, pregnancy status, bleeding risk, and other factors.

More than one session may be needed.

Ureteroscopy With Laser Lithotripsy

During ureteroscopy, a small scope passes through the urethra and bladder into the ureter or kidney.

The stone may be:

• Removed with a small basket
• Broken with a laser
• Fragmented and extracted

A temporary ureteral stent may be placed to support drainage.

Percutaneous Nephrolithotomy

Percutaneous nephrolithotomy, or PCNL, is commonly used for large, complex, or branching kidney stones.

The surgeon creates a small passage through the back into the kidney and removes the stone using specialized instruments.

Emergency Urinary Drainage

An infected, obstructed urinary system normally requires urgent drainage before definitive stone treatment.

Drainage may use:

• A ureteral stent
• A nephrostomy tube placed through the back

Open or Laparoscopic Surgery

Open, laparoscopic, or robotic surgery is uncommon for routine kidney stones but may be considered for selected complex situations.

Why Should a Passed Kidney Stone Be Analyzed?

Stone analysis identifies the material inside a passed or surgically removed stone.

Knowing the composition may help distinguish between:

• Calcium oxalate
• Calcium phosphate
• Uric acid
• Struvite
• Cystine
• Medicine-related stones
• Other uncommon materials

The result may change:

• Diet advice
• Fluid targets
• Medicine choices
• Blood testing
• Genetic evaluation
• Follow-up frequency

If you retrieve a stone, allow it to dry and store it according to the instructions provided by your clinic or laboratory.

Who Needs a 24-Hour Urine Test?

A 24-hour urine collection measures the amount and concentration of substances linked to stone formation.

It may assess:

• Total urine volume
• Calcium
• Oxalate
• Citrate
• Uric acid
• Sodium
• Creatinine
• Urine pH
• Other measurements

Testing may be especially useful for:

• Recurrent stone formers
• People with multiple stones
• People with one functioning kidney
• Children or young adults with stones
• People with cystine, uric acid, infection, or unusual stones
• People with bowel disease or bariatric surgery
• People with a strong family history
• People who want a targeted prevention plan

The collection must include all urine produced during the specified period. Missing samples can make the result less reliable.

How Can Kidney Stones Be Prevented From Returning?

Recurrence prevention should begin with understanding:

• The stone composition
• Urine volume
• Blood results
• 24-hour urine chemistry
• Diet and fluid habits
• Medicines
• Family and medical history

Common prevention measures may include:

• Drinking enough fluid to maintain dilute urine
• Reducing excess sodium
• Eating an appropriate amount of dietary calcium
• Moderating selected animal proteins
• Personalizing oxalate intake
• Increasing citrate when indicated
• Treating urinary infections
• Managing gout, diabetes, obesity, or bowel disease
• Taking prescribed preventive medicine
• Repeating urine and imaging tests when advised

Kidney-stone treatment differs from long-term CKD treatment. Read Kidney Disease Treatment: Tests, Medicines, Diet, and Daily Care.

How Much Fluid Helps Prevent Kidney Stones?

Drinking enough liquid, mainly water, is one of the most important prevention strategies for many stone formers.

Many recurrent stone formers are advised to drink enough to produce a high daily urine volume. The exact drinking amount varies because fluid is lost through sweat, breathing, exercise, heat, vomiting, and diarrhea.

Your target should consider:

• 24-hour urine volume
• Climate
• Physical activity
• Body size
• Pregnancy
• Kidney function
• Heart function
• Medicines
• Fluid restrictions

Practical Fluid Habits

• Spread fluids across the day.
• Drink more when sweating heavily if medically appropriate.
• Keep water accessible at work or while traveling.
• Drink with meals.
• Use a reusable bottle with a known volume.
• Follow a clinician-set target rather than relying only on urine color.

Urine color can be affected by medicines, vitamins, blood, and food, so it is not a perfect measurement.

Do not follow a high-fluid target without professional advice if you have kidney failure, heart failure, severe swelling, low urine output, or a prescribed fluid restriction.

Should People With Calcium Stones Avoid Calcium?

Usually not.

An unnecessarily low-calcium diet may increase calcium oxalate stone risk because less calcium is available inside the intestine to bind oxalate.

Many stone formers are advised to:

• Obtain an appropriate amount of calcium from food
• Consume calcium-containing foods with meals
• Avoid extreme calcium restriction
• Discuss calcium supplements with a healthcare professional

Supplement timing and dose matter. A supplement may be necessary for bone health or another medical reason, but it should be considered alongside stone history and diet.

How Do Sodium and Animal Protein Affect Stone Risk?

Sodium

High sodium intake can increase calcium released into urine, which may increase calcium-stone risk in susceptible people.

Common high-sodium sources include:

• Processed meat
• Fast food
• Instant noodles
• Packaged soup
• Salty snacks
• Pickled foods
• Commercial sauces
• Many frozen meals

Compare sodium per serving and account for the number of servings eaten.

Animal Protein

High intake of selected animal proteins may affect uric acid, urine acidity, calcium, and citrate.

A personalized plan may reduce portions or frequency of:

• Organ meats
• Large portions of red meat
• Selected seafood
• Processed meat

Protein needs should still support muscle, nutrition, age, pregnancy, and medical conditions.

Should You Avoid High-Oxalate Foods?

Not every kidney-stone patient needs a broad low-oxalate diet.

Oxalate restriction is most relevant to selected people with calcium oxalate stones and high urine oxalate.

Foods that may contain substantial oxalate include:

• Spinach
• Rhubarb
• Beet greens
• Selected nuts
• Chocolate or cocoa
• Wheat bran
• Strong black tea

The amount varies by food, portion, preparation, and database.

A safer approach may include:

• Avoiding extreme portions of the highest-oxalate foods
• Eating an appropriate calcium source with meals
• Maintaining adequate fluid intake
• Avoiding excessive vitamin C supplements when advised
• Working with a stone-focused dietitian

Do not eliminate a wide range of nutritious plant foods without confirming that urine oxalate is a concern.

How Does Prevention Differ by Stone Type?

Which Preventive Medicines May Be Used?

Depending on stone type and test results, a clinician may prescribe:

• Potassium citrate
• A thiazide-type diuretic
• Allopurinol
• Medicine for cystinuria
• Other treatment for an underlying metabolic condition

These medicines require individualized selection and monitoring.

Stone-prevention nutrition differs from a general CKD diet. For broader kidney nutrition guidance, read Diet for Kidney Disease: Foods and a Safer Eating Guide.

For adaptable kidney-health food ideas, read Kidney Healthy Foods: Best Foods, Tips, and Meal Ideas.

Can Kidney Stones Damage the Kidneys?

Most stones do not cause permanent kidney damage when identified and treated appropriately.

Risk may increase when there is:

• Prolonged obstruction
• Infection behind a blockage
• Repeated infections
• Stones in both urinary tracts
• One functioning kidney
• Repeated procedures or complex stone disease
• Another underlying kidney condition

For persistent eGFR reduction, urine albumin, or other signs of chronic damage, read Chronic Kidney Disease: Causes, Symptoms, and Treatments.

How Are Kidney Stones Different From a UTI?

A stone and infection can occur together. Fever, chills, cloudy urine, burning urination, or rapidly worsening illness requires prompt medical assessment.

Read UTI Symptoms: Causes, Treatment, and Prevention.

Common Kidney-Stone Mistakes to Avoid

• Do not assume every severe side pain is a kidney stone.
• Do not ignore fever or chills.
• Do not force excessive water during vomiting or severe obstruction.
• Do not assume that a pain-free period proves the stone passed.
• Do not stop follow-up imaging without medical advice.
• Do not remove all dietary calcium.
• Do not eliminate every oxalate-containing food without testing.
• Do not rely on lemon water to dissolve a calcium stone.
• Do not use apple cider vinegar as a primary treatment.
• Do not replace medical care with chanca piedra or kidney-bean broth.
• Do not take potassium citrate without appropriate assessment.
• Do not discard a passed stone when analysis is available.

What Questions Should You Ask a Urologist?

• Where is the stone located?
• How large is it?
• Is it blocking urine flow?
• Is my kidney function affected?
• Is there evidence of infection?
• Is it reasonable to wait for the stone to pass?
• Would an alpha-blocker be appropriate?
• Which pain medicine is safest for me?
• When should follow-up imaging be performed?
• When would a procedure become necessary?
• Which procedure best fits the stone's size and location?
• Should I collect the stone for analysis?
• Do I need a 24-hour urine collection?
• What fluid target should I follow?
• Should I change calcium, sodium, protein, oxalate, or citrate intake?
• Do I need preventive medicine?
• Which symptoms require emergency care?