Written by:Fact check:

Overview

What Are Kidney Stones?

Kidney stones are hard deposits made of minerals and salts that form inside the kidneys. A stone may stay in the kidney or move through the urinary tract, including the ureter and bladder. Some stones cause no symptoms, while others can cause severe pain or urinary problems as they move. Kidney stones can affect people of any sex or age.

Symptoms

Kidney Stone Symptoms

Small stones may cause no symptoms while they remain in the kidney. Symptoms often begin when a stone moves into the ureter and irritates or blocks the urinary tract. Common kidney stone symptoms include:

  • Sharp or cramping pain in the side or back is a common symptom.
  • Pain may move from the side or back toward the lower abdomen or groin.
  • Pain or burning with urination can occur as the stone travels through the urinary tract.
  • A frequent or urgent need to urinate may be a sign of a moving stone.
  • Blood in the urine (hematuria) may make the urine pink, red, or brown.
  • Cloudy or foul-smelling urine may occur, especially when infection is present.
  • Nausea can occur along with severe kidney stone pain.
  • Vomiting may occur when pain is intense or the urinary tract is irritated.
  • Fever or chills may indicate an infection and require prompt medical assessment.

Get medical advice

Know when symptoms may be urgent

Severe pain, fever or chills, vomiting that prevents you from keeping fluids down, or difficulty urinating can signal a complication. Seek prompt medical assessment rather than waiting for symptoms to improve.

Causes

What Causes Kidney Stones?

Kidney stones form when urine contains more stone-forming substances than it can keep dissolved. Minerals and salts can then form crystals that grow and join together into a stone. Dehydration and some medical or inherited conditions can make this process more likely.

STONE TYPES

Calcium stones are the most common type and may involve calcium combined with oxalate or phosphate. Uric acid stones can form when urine is too acidic. Struvite stones are linked to certain urinary infections, while cystine stones result from an inherited disorder that causes cystine to enter the urine.

URINARY TRACT TERMS

Kidney stones form in the kidneys, while bladder stones form in the bladder and may have different causes. Both are stones in the urinary tract, but a kidney stone can move downward into the ureter or bladder.

Risk Factors

Kidney Stone Risk Factors

Risk factor typeExamples
Nonmodifiable or inheritedFamily history, previous stones, and inherited conditions such as cystinuria
Modifiable or treatableLow fluid intake, high sodium or animal-protein intake, obesity, certain digestive or metabolic conditions, recurrent urinary infections, and some medicines

Having a risk factor does not guarantee that you will develop a kidney stone. After a stone episode, a clinician can review your health history, diet, medicines, and testing to identify personal risks and guide prevention.

Complications

Kidney Stone Complications

  • Urinary obstruction can block the flow of urine through the ureter.
  • Hydronephrosis is swelling of the kidney caused by backed-up urine.
  • A urinary tract infection can develop when urine flow is blocked or bacteria are present.
  • A kidney infection can occur if a urinary infection spreads upward.
  • Ongoing obstruction or repeated infections may reduce kidney function.
  • People who have had one kidney stone may develop recurrent kidney stones.

Important

Infection and blockage need urgent attention

An obstructed urinary tract with an infection can become dangerous. Fever, chills, severe weakness, or reduced urine with suspected kidney stones requires urgent medical care.

Diagnosis

How Kidney Stones Are Diagnosed

Clinicians review pain and urinary symptoms and examine you for signs of illness. They may ask about previous stones, medical conditions, medicines, diet, and family history. This information helps determine whether a stone, infection, obstruction, or another condition may be causing the symptoms.

LABORATORY TESTS

Urinalysis can look for blood, crystals, and signs of infection, while a urine culture may be used when infection is suspected. Blood tests can assess kidney function and related chemical levels. If a stone is passed, analysis may identify its type and help guide prevention.

IMAGING

Ultrasound, CT, or another imaging test can show a stone’s size, location, and effect on urine flow. The choice depends on symptoms, age, pregnancy status, and clinical need.

Treatment & Management

Kidney Stones Treatment and Management

Kidney stones treatment depends on the stone’s size, location, and composition, as well as your symptoms, overall health, and whether infection or blockage is present. A clinician will recommend the safest approach for the specific stone.

ApproachWhen it may be used
Observation and medicinesFor selected small stones that may pass safely, with clinician-directed pain control, fluids when appropriate, nausea treatment, and follow-up
Medical expulsive therapyMedicines may help some stones pass through the ureter when prescribed and monitored by a clinician
Shock wave lithotripsyUses focused shock waves to break a suitable stone into smaller pieces that can pass
UreteroscopyUses a small scope to reach the stone, remove it, or break it into pieces
Percutaneous nephrolithotomyMay be used for larger or complex stones through a small opening in the back
Urgent treatmentAn infected obstruction requires urgent medical treatment to relieve blockage and control the infection

Prevention

How to Prevent Kidney Stones

  • Drink enough fluid as advised by your healthcare professional.
  • Reduce excess sodium in your diet.
  • Follow individualized dietary guidance based on your stone type and health needs.
  • Avoid extreme high-protein diets when they are not appropriate for you.
  • Maintain a healthy weight through sustainable eating and activity habits.
  • Manage medical conditions that may contribute to stone formation.
  • Take prescribed preventive medicines as directed.

Outlook and Prognosis

Outlook and Prognosis for Kidney Stones

Many smaller stones pass without a procedure, while larger or complicated stones may need treatment. The time required and the amount of discomfort vary according to the stone’s size and location. Follow-up is important even after symptoms improve because another stone may form.

When Should You See a Doctor

When Should You See a Doctor for Kidney Stones?

Contact a clinician

Get medical advice promptly

Contact a clinician for severe or persistent kidney stone pain, blood in the urine, repeated vomiting, difficulty urinating, or symptoms that do not improve. These symptoms may need testing and treatment.

Seek urgent care

Recognize emergency warning signs

Seek emergency care for fever or chills with suspected kidney stone symptoms, severe weakness, confusion, inability to keep fluids down, or very little or no urine. These may indicate a serious infection or urinary obstruction.

Branches

2 topics

Symptoms

3 topics