Most kidney stones smaller than 5mm will pass on their own with enough water, over-the-counter pain relief, and time. The process usually takes a few days to several weeks. About 1 in 10 Americans develop a kidney stone at some point, and roughly half get another one within 10 years if they don’t change anything (NIH/NIDDK 2024 Annual Data Report). Knowing how to pass a kidney stone safely, and when to stop waiting and get help, can save you thousands in ER and procedure costs.
A kidney stone is a hard mineral deposit (usually calcium oxalate) that forms inside the kidney and can cause severe pain when it moves into the ureter. Around 80–85% of stones are calcium-based. The rest are mostly uric acid stones that develop in people with low urine pH levels.
This article covers what causes stones, how to pass them at home, and five changes that actually reduce your recurrence risk. We won’t go deep on surgical techniques. If you need that, talk to your urologist.
What Causes Kidney Stones?
Stones form when minerals like calcium, oxalate, or uric acid concentrate in your urine and crystallize. The crystals clump together and grow into hard masses.
The biggest driver? Not drinking enough water. I’ve treated patients who barely hit a liter of fluid daily and couldn’t figure out why stones kept forming. Your kidneys can’t flush minerals out if there isn’t enough fluid moving through. Other risk factors include high-sodium diets, obesity, and family history. Men develop stones more often, though NIH data from 2024 shows that gap has been narrowing.
When a stone dislodges and enters the ureter, it blocks urine flow. That’s where the pain hits: flank pain, nausea, sometimes blood in the urine. As the stone moves lower, bladder pressure and groin pain show up. If you’re unsure whether it’s a stone, the early signs and symptoms are pretty distinctive once you know what to look for.
How Do You Pass a Kidney Stone?
Stone size determines your game plan. That’s the one thing most articles bury under paragraphs of background.
Under 5mm, about 90% pass on their own. Between 5mm and 10mm, you’ll likely need medication. Over 10mm, you’re almost certainly looking at a procedure. The 2026 AUA surgical guideline gives alpha-blockers (like tamsulosin) a Grade A recommendation for distal ureteral stones 10mm or smaller. But here’s a contrarian point most sites skip: evidence for tamsulosin on stones stuck higher in the ureter is much weaker. Plenty of ERs still prescribe it automatically regardless of location.
For passable stones, the plan is water (2.5+ liters daily), ibuprofen for pain, and patience. Your doctor may ask you to strain your urine so you can catch the stone for lab analysis. Passage takes anywhere from days to several weeks. The four stages of passing a stone are predictable, and the worst pain drops off once it reaches your bladder.
If you develop fever, can’t keep fluids down, or the pain becomes unbearable, stop waiting. Leaving a stone untreated when it’s causing obstruction can lead to kidney infection and a hospital stay that adds $15,000–$35,000+ to your bill. Ureteroscopy with laser runs $10,000–$25,000 self-pay. Shockwave lithotripsy costs $8,000–$15,000 (MDsave 2025–2026 national averages).
5 Tips to Prevent Kidney Stones From Returning
Recurrence risk sits at roughly 50% within 5–10 years without targeted prevention (AUA Medical Management Guideline). Most people skip prevention because they feel fine. Then the next stone hits.
1. Drink enough water to produce 2.5 liters of urine daily. A National Kidney Foundation analysis found this cut stone risk by 50%. Pale yellow urine means you’re on track. Dark yellow means you’re behind.
2. Eat calcium-rich foods, not supplements. Yogurt, beans, lentils, and seeds bind oxalate in your gut before it reaches your kidneys. Aim for 1,000–1,200 mg daily from food. Supplements taken on an empty stomach can actually raise stone risk. If you’re building a kidney stone prevention diet, this is the most misunderstood piece.
3. Add lemon juice to your water. Citrate blocks stone formation by binding to calcium. About half a cup of lemon concentrate diluted in water each day can increase urine citrate levels enough to matter.
4. Keep sodium under 2,300 mg daily. High sodium pushes more calcium into your urine. Most Americans exceed this by lunch. Check labels on canned food, deli meat, and anything from a drive-through.
5. Limit animal protein. Red meat, eggs, and seafood raise uric acid and lower urine citrate. If you’re prone to stones, keep meat portions roughly the size of a deck of cards per meal.
One thing I’ll push back on: the internet loves recommending cranberry juice and beer for kidney stones. Neither has strong prevention evidence. Beer can actually worsen dehydration. Stick with water and lemon.
If you’re trying to pass a kidney stone right now, the short answer for small stones is water, pain control, and time. For anything larger or more complicated, get to a urologist. And don’t skip the follow-up. Ask for a stone composition analysis and a 24-hour urine test. Those two results tell your doctor exactly what type of stone you form and how to stop the next one. Most people never ask for this, and most people end up right back where they started. A urology team experienced in stone disease can walk you through the entire process, from the diagnosis through a plan built around your specific results. Modern Urology’s patient education is backed by a content team that focuses on medical accuracy, so the information you find here is current and evidence-based.
FAQs
How long does it take to pass a kidney stone?
Most small kidney stones (under 5mm) pass within 1 to 3 weeks with adequate hydration and pain management. Stones between 5mm and 10mm can take several weeks to a few months. The 2026 AUA guideline recommends trying alpha-blockers for up to 30 days for distal ureteral stones 10mm or smaller before considering surgical options.
Can you pass a kidney stone without knowing it?
Yes. Very small stones (under 2mm) can pass with little to no pain. You might notice slight discomfort or see the stone in your urine, but many people pass tiny stones without ever realizing it. This is more common with first-time stones that haven’t grown large enough to block the ureter.
How much does kidney stone treatment cost without insurance?
Self-pay costs vary widely by procedure. An ER visit for pain management runs $3,000 to $8,000. Shockwave lithotripsy (ESWL) costs $8,000 to $15,000. Ureteroscopy with laser lithotripsy ranges from $10,000 to $25,000. Percutaneous nephrolithotomy (PCNL) for large stones can reach $20,000 to $35,000 or more (MDsave 2025–2026 national averages).
What is the best thing to drink to pass a kidney stone?
Plain water is the most effective fluid for passing a kidney stone. You should aim for enough to produce at least 2.5 liters of urine daily. Adding fresh lemon juice increases citrate levels, which helps prevent new stones. Coffee and tea count toward fluid intake, but avoid sugary sodas and grapefruit juice, which may increase stone risk.
Does kidney stone size affect whether you need surgery?
Yes. Stones under 5mm pass on their own about 90% of the time. Between 5mm and 10mm, medication like alpha-blockers may help, but passage rates drop. Stones over 10mm almost always need a procedure such as ureteroscopy or ESWL. The 2026 AUA guideline uses the 10mm threshold as a key decision point for medical vs. surgical management.
What foods should you avoid to prevent kidney stones?
For calcium oxalate stones (the most common type), limit high-oxalate foods like spinach, rhubarb, sweet potatoes, and nuts. Keep sodium under 2,300 mg daily and reduce animal protein intake. The National Kidney Foundation recommends getting calcium from food sources (1,000–1,200 mg daily) rather than supplements, which can increase stone risk when taken on an empty stomach.
Dr. Carolyn Fronczak is the founder and Medical Director of Modern Urology Colorado. She is board certified by the American Board of Urology, with expertise in both men’s and women’s urologic care. She completed her medical degree at the University of Colorado School of Medicine and her surgical training at the University of Nebraska Medical Center. Dr. Fronczak has treated thousands of patients in the Boulder/Denver area.