How to Pass a Kidney Stone: Symptoms, Stages, and Proven Strategies

What to Expect When Passing a Kidney Stone

Passing a kidney stone typically causes sudden, severe flank pain that may radiate to the groin, along with blood in the urine, nausea, and urinary urgency. Stones smaller than 5 to 6 millimeters have the highest chance of passing spontaneously within about four weeks, while larger stones often require medical intervention. This overview explains how stones move through the urinary tract, how long passage usually takes, and which symptoms and test results indicate it is time to seek urgent care. The information below draws on current clinical guidance to help you recognize warning signs, choose appropriate treatments, and plan follow-up to reduce recurrence risk.

Anatomy and Physiology: How Stones Form and Move

Kidney stones are hard mineral and salt deposits that form in the kidneys when urine contains more crystallizing substances than the fluid in your urine can dilute. Common types include calcium oxalate, calcium phosphate, uric acid, struvite, and cystine stones. Stones may remain in the kidney or travel into the ureter, the narrow tube connecting each kidney to the bladder. The ureter’s muscular contractions propel the stone toward the bladder, a process that can cause waves of intense pain known as renal colic. Factors such as urine concentration, pH, diet, hydration, genetics, and underlying medical conditions affect stone formation and passage likelihood.

Stone Size and Location Matter

Stone diameter strongly predicts whether a stone will pass without surgery. In general, stones under 4 millimeters have about an 80 percent chance of spontaneous passage, while stones between 4 and 6 millimeters pass spontaneously in roughly half of cases. Stones larger than 6 millimeters have a significantly lower chance of passing on their own and often require urologic procedures. Location also matters: stones that move beyond the mid-ureter, near the bladder junction, or at narrow anatomic strictures are less likely to advance without intervention.

Stages of Passing a Kidney Stone

Kidney stone passage commonly unfolds in three overlapping phases: pre-passage, active passage, and post-passage. During the pre-passage phase, you may notice intermittent flank discomfort, subtle blood in the urine, and an increased urge to urinate as the stone approaches the ureter. The active passage phase involves intense, colicky pain that peaks in waves, often accompanied by nausea, vomiting, and visible or microscopic hematuria. Once the stone reaches the bladder and passes through the urethra, you may feel a brief stinging sensation during urination, followed by relief. Not all stones pass completely on the first attempt; some fragment into smaller pieces that pass over several days.

What to Track During Active Passage

• Timing and pattern of pain, noting when it intensifies or eases
• Changes in urine color, clarity, and presence of blood clots
• Urinary frequency, urgency, and ability to start urination
• Fever, chills, or lightheadedness, which may indicate infection

Proven Strategies to Help Pass a Stone

Increasing fluid intake is the cornerstone of conservative management, because higher urine volume can help move the stone and reduce blockage risk. Many clinicians recommend aiming for enough fluids to produce at least 2 liters of urine per day, which often means drinking roughly 2 to 3 liters of water daily unless you have a medical reason to restrict fluids. Over-the-counter nonsteroidal anti-inflammatory drugs can reduce pain and inflammation, while certain alpha-blocker medications may relax the ureter and improve passage rates for stones in the lower ureter. Medical expulsive therapy is typically considered for stones between 5 and 10 millimeters that are causing persistent symptoms but no signs of infection or kidney damage. If symptoms worsen or do not improve within a few days, imaging and urology evaluation can clarify whether a different approach is needed.

When to Seek Urgent Care

Seek immediate medical attention if you develop fever or chills, persistent vomiting that prevents fluid intake, worsening abdominal or flank pain not controlled by medication, or a marked decrease in urine output. These signs may indicate infection, severe obstruction, or impaired kidney function, which require prompt intervention. Stones that fail to pass within 4 to 6 weeks, or those causing repeated episodes of pain or infection, should also prompt a urology consultation to discuss definitive treatment options.

Medical and Surgical Options When Stones Do Not Pass

When spontaneous passage is unlikely, several minimally invasive procedures can remove or fragment stones. Extracorporeal shock wave lithotripsy uses focused sound waves to break stones into small fragments that can pass naturally. Ureteroscopy involves inserting a thin scope through the urethra and bladder to reach the ureter or kidney, allowing direct removal or fragmentation of stones. For larger stones, percutaneous nephrolithotomy may be recommended, in which a small tract is created through the skin to remove stone fragments. The choice of procedure depends on stone size, location, composition, kidney anatomy, and your overall health, with the goal of relieving obstruction and preserving kidney function.

Recovery, Follow-Up, and Prevention

Recovery after stone passage varies: you may resume normal activities within a few days if symptoms resolve, but you should avoid heavy lifting or intense exercise until your clinician confirms clearance. Drinking adequate fluids, maintaining a balanced diet, and addressing metabolic risk factors can reduce the chance of new stones. Depending on stone composition and underlying causes, your clinician may recommend 24-hour urine testing, blood work, or imaging to guide long-term prevention strategies. Regular follow-up, including periodic imaging and review of risk factors, supports early detection of new stones and helps maintain kidney health over time.

Summary and Key Takeaways

• Smaller stones (
• Severe pain, fever, persistent vomiting, or reduced urine output are red flags that require urgent care.
• Hydration, pain control, and, when appropriate, medications like alpha-blockers can support natural passage.
• Procedures such as lithotripsy, ureteroscopy, or percutaneous nephrolithotomy can remove stones that do not pass or cause complications.
• Long-term prevention often includes fluid intake, dietary adjustments, and targeted testing based on stone composition and metabolic profile.