Most kidney stones pass on their own with pain management and fluids, but the treatment you need depends almost entirely on the stone’s size. Stones smaller than 5 mm pass without intervention roughly 75% of the time. Larger stones, especially those above 10 mm, often require a procedure to break them up or remove them.
Which Stones Pass on Their Own
Your stone’s size is the single biggest factor in whether you’ll need a procedure or can wait it out. The spontaneous passage rates break down like this:
- 1 to 4 mm: About 72% to 87% pass without intervention
- 5 to 6 mm: About 60% to 72% pass
- 7 to 9 mm: About 33% to 56% pass
- 10 mm or larger: Around 25% or less pass naturally
Where the stone sits in your urinary tract matters too. Stones closer to the bladder (in the lower ureter) have a shorter distance to travel and tend to pass more easily than stones still near the kidney. If your stone is small and in a favorable location, your doctor will typically recommend a trial of “watchful waiting” for up to four weeks, managing your pain at home while the stone works its way out.
Managing the Pain
Kidney stone pain can be among the most intense pain people experience, and controlling it is the first priority. Anti-inflammatory painkillers (NSAIDs) are the first-line choice because they work better for this specific type of pain than opioids. Ibuprofen at 800 mg or naproxen at 500 mg are the most commonly used over-the-counter options. In an emergency room, you may receive an intravenous anti-inflammatory for faster relief.
NSAIDs work especially well for kidney stone pain because they reduce the swelling and spasm in the ureter, the narrow tube connecting your kidney to your bladder. That addresses the root cause of the pain, not just the sensation. If you have kidney disease, heart failure, or stomach ulcer issues, NSAIDs aren’t safe for you, and your doctor will choose an alternative.
Medication to Help a Stone Pass
For stones between 5 and 10 mm in the ureter, your doctor may prescribe a medication called an alpha-blocker (most commonly tamsulosin, taken once daily). This relaxes the smooth muscle in the ureter, widening the passage so the stone can move through more easily. The typical course lasts about 28 days or until the stone passes, whichever comes first.
This approach, called medical expulsive therapy, makes a meaningful difference for larger stones. In pooled studies, 85% of patients taking tamsulosin passed their stone compared to 66% on placebo, a benefit large enough that only five patients need to be treated for one additional person to avoid surgery. For stones under 5 mm, though, the medication doesn’t appear to improve passage rates. Those stones are already small enough to pass on their own most of the time.
Dissolving Uric Acid Stones
One specific type of kidney stone, uric acid stones, can actually be dissolved with medication rather than removed. Uric acid stones form when urine is too acidic. By raising the urine’s pH to between 6.5 and 7.0, you create conditions where the stone gradually breaks down on its own.
The standard approach uses potassium citrate, taken in divided doses throughout the day, with the amount adjusted based on repeated urine pH testing. Some people also take sodium bicarbonate to help reach the target pH. This process requires patience and regular monitoring, but it can eliminate stones without any procedure. It only works for uric acid stones, which account for roughly 5% to 10% of all kidney stones. Your doctor can determine the stone type through a urine test, imaging, or by analyzing a stone you’ve previously passed.
Shock Wave Lithotripsy
When a stone won’t pass on its own, shock wave lithotripsy (SWL) is the least invasive procedural option. You lie on a table while a machine sends focused sound waves through your body to break the stone into smaller fragments that you then pass naturally over the following days or weeks. It requires sedation or light anesthesia but no incisions.
SWL works best for stones under 2 cm that are located in the kidney or upper ureter. It clears stones successfully about 64% of the time. That success rate is lower than other procedures, which is why SWL isn’t recommended as first-line treatment for stones larger than 1 cm in the lower part of the kidney (a location where fragments have a harder time draining) or stones larger than 2 cm anywhere in the kidney. You may need more than one session. Recovery is relatively quick since there’s no surgical wound, though you can expect some soreness and blood in your urine for a few days.
Ureteroscopy
Ureteroscopy (URS) involves passing a thin, flexible scope up through your urethra, into the bladder, and up into the ureter to reach the stone directly. A laser fiber is threaded through the scope to break the stone into tiny fragments, which are then extracted with a small basket or left to pass on their own.
This procedure has a higher stone clearance rate than shock wave lithotripsy, roughly 78% compared to 64%, with similar complication rates. The tradeoff is a slightly longer procedure and about a quarter-day longer hospital stay on average, though most people go home the same day. After ureteroscopy, your surgeon will often place a temporary stent, a thin tube inside the ureter that keeps it open while swelling goes down. The stent stays in for a few days to a few weeks and is removed in a brief office procedure. Stents can cause discomfort, a frequent urge to urinate, and some blood in the urine, but these symptoms resolve once the stent comes out.
Ureteroscopy is a good option for stones up to about 2 cm in the ureter or kidney, and it’s often preferred when SWL isn’t ideal due to stone location, size, or composition.
Percutaneous Nephrolithotomy
For large stones over 2 cm, or complex branching stones that fill much of the kidney’s drainage system (called staghorn stones), the recommended treatment is percutaneous nephrolithotomy (PCNL). This involves making a small incision in your back and passing a scope directly into the kidney to break apart and remove the stone.
PCNL has the highest stone-free rate of any procedure for large stones and is considered first-line therapy when stones exceed 2 cm. For stones between 1 and 2 cm, a smaller version of the procedure called mini-PCNL may be offered, which uses a thinner scope and a smaller incision while achieving better clearance rates than ureteroscopy. PCNL requires general anesthesia and typically a hospital stay of one to two days. Recovery takes longer than less invasive options, usually one to two weeks before returning to normal activity. It’s also the go-to approach when previous attempts with shock waves or ureteroscopy have failed.
Preventing the Next Stone
About half of people who form a kidney stone will form another within 10 years, so prevention matters. The single most effective thing you can do is drink more water. People who’ve had a stone should aim for at least 2 liters (8 cups) of water per day, and ideally 3 liters (12 cups). The goal is to produce enough dilute urine that minerals can’t concentrate and crystallize. If your urine is consistently pale yellow to clear, you’re in the right range.
Beyond hydration, dietary changes depend on what type of stone you form. For calcium oxalate stones, the most common type, reducing sodium and animal protein intake helps more than cutting calcium. In fact, getting adequate calcium from food (not supplements) actually lowers your risk because dietary calcium binds to oxalate in the gut before it reaches the kidneys. Limiting high-oxalate foods like spinach, rhubarb, nuts, and beets can also help if your oxalate levels are high. For uric acid stones, reducing red meat and shellfish intake and maintaining a less acidic urine pH with potassium citrate are the primary strategies.
If you’ve passed a stone, saving it for analysis gives your doctor the clearest picture of what caused it and how to tailor your prevention plan.