Most kidney stones pass on their own with fluids, pain management, and time. Stones smaller than 5 millimeters have the best odds of passing without any procedure, while stones larger than 10 millimeters almost always need medical intervention. The approach depends primarily on two things: how big the stone is and where it’s located in your urinary tract.
Which Stones Pass on Their Own
A stone’s size and position in the ureter (the tube connecting your kidney to your bladder) determine whether you can wait it out. Stones sitting in the lower portion of the ureter, closest to the bladder, have the highest chance of passing naturally. For stones under 5 mm in that location, about 74% will pass without intervention. At 5 mm, those odds drop to around 45%. Stones larger than 5 mm in the lower ureter pass only about 25% of the time.
Higher up in the ureter, the numbers get worse. A stone under 5 mm in the upper ureter passes roughly 53% of the time, and stones over 5 mm at that level essentially don’t pass on their own. The general rule: if your stone is under 5 mm, your doctor will likely recommend a trial of watchful waiting with aggressive hydration. If it’s between 5 and 10 mm, you may still avoid a procedure, but medication can help. Above 10 mm, you’re almost certainly looking at some form of intervention.
Managing Pain While You Wait
Kidney stone pain, called renal colic, can be among the most intense pain people experience. Anti-inflammatory medications like ibuprofen are the recommended first-line treatment. They work by reducing the swelling and spasm in the ureter wall, which is what actually causes most of the pain. A meta-analysis comparing pain relief options found that anti-inflammatories provide the most sustained relief with fewer side effects than opioid painkillers or acetaminophen. Opioids are reserved for cases where anti-inflammatories aren’t enough or can’t be used safely.
Drink plenty of water to keep urine flowing and help push the stone along. There’s no magic number, but aiming for enough fluid to produce clear or light yellow urine is a reasonable target.
Medications That Help Stones Pass
For stones between 5 and 10 mm, your doctor may prescribe a type of muscle relaxant that widens the ureter to help the stone move through. The most commonly used one increases your stone expulsion rate by about 44% compared to waiting alone, shortens the time it takes to pass the stone, and reduces the number of painful colic episodes along the way. It also lowers the chance you’ll ultimately need a surgical procedure.
This medication works best for stones in the lower ureter. For stones 5 mm or smaller, the benefit is minimal since most of those will pass on their own anyway. The sweet spot is stones in the 5 to 10 mm range, where the medication makes the biggest difference.
Dissolving Uric Acid Stones
Uric acid stones are unique: they’re the only type of kidney stone that can be dissolved with oral medication. The treatment works by making your urine more alkaline, raising its pH to between 6.5 and 7.0. At that level, uric acid can’t crystallize and existing stones gradually break down.
This approach has a better-than-50% success rate for complete dissolution in most studies, with some showing success rates above 80%. Your doctor can identify uric acid stones through a CT scan (they tend to have a distinct appearance) or by analyzing a stone you’ve previously passed. If dissolution therapy is an option for you, it can spare you a procedure entirely, though it requires monitoring your urine pH at home and may take several weeks to fully work.
Shock Wave Lithotripsy
When a stone won’t pass on its own but isn’t enormous, shock wave lithotripsy is often the first procedure considered. You lie on a table while a machine sends focused sound waves through your body to shatter the stone into smaller fragments that can then pass in your urine. It’s done under sedation, and you go home the same day.
Success rates vary widely, from about 46% to 91% depending on the stone’s characteristics. Two factors matter most: density and size. Stones that are less dense on a CT scan and smaller than 5 mm respond best. Harder, larger stones are more resistant to the shock waves. Overall, about two-thirds of patients achieve a successful outcome, but some need a repeat session. The location of the stone, whether in the kidney or ureter, doesn’t significantly affect success rates.
Ureteroscopy and Laser Treatment
For stones that don’t respond to shock waves, or for lower ureteral stones where a more direct approach makes sense, ureteroscopy is the go-to option. A thin, flexible scope is passed through your urethra and bladder into the ureter, and a laser breaks the stone into tiny fragments. Larger pieces are removed with a small basket tool, and most remaining fragments pass within 24 hours, though some can take several weeks.
Recovery is relatively quick. You can expect some blood in your urine for two to three days afterward. Most people return to normal activities within a few days, though you should avoid strenuous exercise or sports for about a week or until any blood in the urine clears. A temporary stent (a small tube inside the ureter) is sometimes placed to keep things open while swelling subsides, and it’s removed at a follow-up visit.
Surgery for Large or Complex Stones
Stones larger than 20 mm, or “staghorn” stones that branch out and fill much of the kidney’s internal space, typically require a procedure called percutaneous nephrolithotomy. A surgeon makes a small incision in your back and passes instruments directly into the kidney to break up and remove the stone. It’s more invasive than the other options and requires general anesthesia and a hospital stay, but it’s the most effective way to clear very large stones that other methods can’t handle.
Dietary Changes to Prevent Recurrence
About half of people who pass a kidney stone will form another one within five to ten years, so prevention matters. The single most impactful change is drinking more water. Beyond that, dietary adjustments depend on what type of stone you had.
For calcium oxalate stones, the most common type, it may seem logical to cut calcium from your diet, but that’s actually counterproductive. Calcium binds to oxalate in your digestive tract and prevents it from reaching your kidneys. Getting enough calcium through food (not supplements, which can have the opposite effect if taken separately from meals) helps reduce stone risk. At the same time, limiting high-oxalate foods like spinach, rhubarb, nuts, and chocolate can help. The ideal daily oxalate limit varies by person, so it’s worth discussing with your care team after a stone analysis.
Reducing sodium is another practical step, since high salt intake increases the amount of calcium in your urine. Cutting back on animal protein also helps, particularly for uric acid stones, because it lowers uric acid production and makes urine less acidic.
Signs That Need Immediate Attention
Most kidney stones, even painful ones, aren’t dangerous. But certain symptoms signal a complication that needs urgent care: pain so severe you can’t sit still or find a comfortable position, pain with nausea and vomiting, fever and chills alongside the pain, visible blood in your urine, or difficulty urinating. Fever with a kidney stone can indicate an infection behind the blockage, which can become serious quickly and may require emergency drainage.