Most kidney stones pass on their own, but how you get rid of one depends almost entirely on its size. Stones smaller than 5 mm have about a 90% chance of passing without any procedure. Stones between 5 mm and 10 mm drop to roughly 50-50 odds. Anything larger than that usually requires medical intervention.
Passing a Small Stone at Home
If your stone is small enough to pass naturally, the process takes one to two weeks for stones under 4 mm, and closer to two to three weeks for slightly larger ones. During that time, your main jobs are staying hydrated, managing pain, and watching for warning signs.
Drink at least 2.5 to 3 liters of fluid per day. Water is the best choice. Coffee, tea, and low-calorie orange juice are also reasonable options. Avoid sugar-sweetened sodas, apple juice, grapefruit juice, and punch, all of which are linked to higher stone risk. The goal is to produce enough urine volume to keep flushing the stone through your urinary tract.
Your doctor may ask you to strain your urine so the stone can be caught and analyzed. Knowing the stone’s composition helps guide treatment if you’re prone to forming more.
Managing the Pain
Kidney stone pain can be severe, often hitting in waves as the stone moves through the ureter. Anti-inflammatory painkillers like ibuprofen or naproxen are the preferred first-line option. They work by reducing the swelling and spasm in the ureter wall, which is what actually causes most of the pain. Compared to opioid painkillers, anti-inflammatories provide longer-lasting relief, cause less vomiting, and reduce the need for additional pain medication.
A heating pad on your back or side can help between doses. If the pain becomes so intense you can’t sit still, or it comes with fever, chills, vomiting, blood in your urine, or difficulty urinating, that’s a situation that needs immediate medical attention. These signs can indicate infection or a complete blockage, both of which can damage your kidney.
Medications That Help Stones Pass
For stones in the 5 to 10 mm range, doctors sometimes prescribe a medication that relaxes the muscles in your ureter, making it easier for the stone to slide through. This approach, called medical expulsive therapy, increases the chance of passing a larger stone by about 22%. For stones already under 5 mm, the medication doesn’t appear to offer any benefit over simply waiting.
Dissolving Uric Acid Stones
Uric acid stones are the only type of kidney stone that can be dissolved with medication instead of removed. If imaging or a urine test confirms you have uric acid stones, your doctor can prescribe an alkalinizing agent, typically potassium citrate, that raises the pH of your urine to between 6.5 and 7.0. At that pH level, the chemical environment becomes unfavorable for uric acid crystals, and the stone gradually breaks down. This requires regular monitoring and dose adjustments based on urine pH readings, but it can eliminate the need for a procedure entirely. Bicarbonate-rich mineral water can support this process as well.
Shock Wave Lithotripsy (ESWL)
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 break the stone into smaller fragments. There are no incisions. Success rates range widely, from 30% to 90%, depending on the stone’s size, location, type, and your body composition. Stones in the upper ureter or certain parts of the kidney respond best.
Recovery is quick. Most people return to normal activities within a few days. You’ll pass stone fragments in your urine for days to weeks afterward, which can cause mild discomfort but is far less intense than the original stone pain.
Ureteroscopy
For stones in the ureter or lower kidney that aren’t good candidates for shock waves, ureteroscopy is the next step. A thin, flexible scope is passed through the urethra and bladder up into the ureter, where a laser breaks the stone into tiny pieces. The fragments are either extracted directly or left small enough to pass on their own. Studies show that about 95% of patients end up with residual fragments smaller than 4 mm, which are small enough to pass naturally. The procedure is done under anesthesia, and most people go home the same day.
A temporary stent (a small tube) is often placed in the ureter afterward to keep it open while swelling goes down. The stent is removed in the office a few days to a couple of weeks later. It can cause some urgency and discomfort while it’s in place, which is the most common complaint about the procedure.
Surgery for Large or Complex Stones
Percutaneous nephrolithotomy is reserved for the biggest and most complex stones, typically those larger than 2 centimeters or staghorn stones that fill multiple branches of the kidney’s drainage system. It’s also used when other treatments have failed. A surgeon makes a small incision in your back and passes a scope directly into the kidney to break up and remove the stone. Unlike the other procedures, this one requires a hospital stay of one to two days and a longer recovery period.
Preventing the Next Stone
About half of people who form one kidney stone will form another within five to ten years, so prevention matters. The single most effective step is maintaining a fluid intake of at least 2.5 liters per day, aiming for urine output of 2 to 2.5 liters. For people with certain metabolic conditions like cystinuria, the target is even higher: 3.5 to 4 liters of fluid daily.
Beyond hydration, prevention depends on what type of stone you formed. Calcium oxalate stones, the most common type, benefit from adequate dietary calcium (which actually binds oxalate in the gut before it reaches your kidneys), moderate sodium intake, and limiting high-oxalate foods like spinach and nuts. Uric acid stones respond to keeping urine less acidic through diet changes or ongoing alkalinizing medication. This is why catching and analyzing your stone is so valuable: it tells you and your doctor exactly what you’re dealing with and how to keep it from happening again.