Most kidney stones pass on their own with time, fluids, and pain management. Stones smaller than 5 millimeters have the best chance of making it out naturally, while larger stones often need medical help ranging from medication to minimally invasive procedures. The approach depends almost entirely on the stone’s size and where it’s sitting in your urinary tract.
When Stones Pass on Their Own
Your body can push out many kidney stones without any procedure at all. The key factor is size. Stones under 5 mm (roughly the width of a pencil lead) pass naturally in the majority of cases, especially when they’ve already traveled to the lower part of the ureter, the tube connecting your kidney to your bladder. At that location, small stones have about a 74% chance of passing. The closer a stone is to the kidney and the larger it is, the less likely it will make the trip on its own. Stones over 5 mm that are still in the upper ureter have essentially a 0% chance of passing without intervention.
If your stone is small enough to wait out, you’ll be told to drink plenty of fluids to keep urine flowing and help push the stone along. Aim for up to 3 liters of fluid per day. You’ll also get a mesh strainer to use every time you urinate. Catching the stone matters: a lab can analyze its composition, which tells your doctor exactly what type of stone you’re forming and how to prevent the next one.
Passing a stone can take days to several weeks. If it hasn’t moved after a few weeks, your doctor will likely recommend a procedure.
Medication to Help Stones Move
For stones between 5 and 10 mm stuck in the lower ureter, doctors often prescribe a daily pill that relaxes the smooth muscle lining your ureter. This widens the passage just enough to let the stone slip through more easily. The medication is typically taken once daily for up to 28 days or until the stone passes, whichever comes first. It’s most effective for that mid-range size where stones are too big to pass quickly on their own but not so large that they need surgery right away.
Managing the Pain While You Wait
Kidney stone pain, called renal colic, can be severe. Anti-inflammatory painkillers (NSAIDs) are the recommended first-line treatment. Compared to opioid painkillers, NSAIDs provide better initial pain relief within the first 30 minutes, reduce the need for additional rescue medication, and cause fewer side effects, particularly less vomiting. If NSAIDs aren’t enough or you can’t take them, acetaminophen or opioids are the backup options. Go to the emergency department if the pain becomes unbearable or you develop a fever, which can signal an infection behind the blockage.
Shock Wave Lithotripsy
When a stone is too large to pass naturally but isn’t massive, shock wave lithotripsy is one of the least invasive options. You lie on a table while a machine sends thousands of high-energy pressure waves through water and into your body, all focused on the stone. The waves break the stone into small fragments that you then pass in your urine over the following days and weeks.
There are no incisions and no scopes inserted into your body. Success rates range widely, from 30% to 90%, depending on the stone’s size, location, and composition. It works best on stones that are larger than 5 mm but not enormous, and it’s typically done as an outpatient procedure. Some stones are too hard or too large for shock waves to break effectively, in which case your doctor will recommend a different approach.
Ureteroscopy With Laser
Ureteroscopy is the most common procedure for stones stuck in the ureter. A urologist passes a thin, flexible scope with a camera on the end up through your urethra, into the bladder, and into the ureter where the stone is lodged. Once they can see the stone, they thread a laser fiber through the scope and use it to break the stone into fragments. The pieces are then plucked out with a tiny basket instrument.
The whole procedure takes one to two hours. There’s no external incision. Afterward, your doctor will often place a temporary tube called a ureteral stent inside the ureter to keep it open while swelling goes down. The stent stays in for a few days to a few weeks, and it comes with some notable side effects. Up to 80% of people with a stent experience bladder irritation, increased urination, blood in their urine, or pain while peeing. A pulling sensation during urination is also common. These symptoms are temporary and resolve once the stent is removed, which is a quick office procedure.
Surgery for Very Large Stones
Percutaneous nephrolithotomy, or PCNL, is reserved for the biggest and most complex stones. It’s typically recommended when a stone is 2 centimeters or larger, when the stone has an irregular shape that makes it impossible to pass through the urinary system, or when other treatments like shock waves or ureteroscopy aren’t viable options.
Unlike the other procedures, PCNL requires a small incision in your back. The surgeon creates a direct channel through the skin into the kidney, then uses instruments to break up and remove the stone. It requires general anesthesia and a hospital stay, making it the most involved option. But for very large stones or branching “staghorn” stones that fill the interior of the kidney, it’s the most effective way to clear everything out in one session.
How Treatment Is Chosen
The decision tree is straightforward. Stones under 5 mm that are moving through the ureter get a trial of watchful waiting with fluids and pain control. Stones between 5 and 10 mm in the lower ureter may get medication to assist passage, with a procedure planned if the stone doesn’t budge within a few weeks. Stones too large for natural passage, those causing a complete blockage, or those paired with signs of infection call for active removal using one of the procedures above. Your doctor picks the specific technique based on stone size, stone location, and your anatomy.
If you’ve been told your stone is small enough to pass, the waiting period is the hardest part. Stay hydrated, strain every drop of urine so you don’t miss the stone, and keep up with pain management. Most small stones will eventually make their way out.