Most kidney stones pass on their own, but what you do during that process can significantly affect your pain levels, how quickly the stone moves, and whether you need a procedure. Stones smaller than 4 mm pass about 80% of the time without intervention, typically within a month. Larger stones have lower odds and longer timelines, so the right approach depends heavily on size.
Managing Pain at Home
Kidney stone pain hits in waves as the stone moves through the ureter, the narrow tube connecting your kidney to your bladder. Anti-inflammatory painkillers like ibuprofen and naproxen are your best first option. A meta-analysis of 18 studies covering over 3,000 patients found that anti-inflammatory drugs matched opioid painkillers for acute kidney stone pain, while causing significantly fewer side effects like vomiting and reducing the need for a second dose of medication by about 24%.
Heat also helps. Placing a heating pad on your side or lower back relaxes the smooth muscle around the ureter and can take the edge off between pain spikes. Warm baths serve the same purpose. Staying mobile, even just walking around the house, may help the stone shift downward.
How Much Water You Actually Need
Drinking enough fluid is the single most important thing you can do while passing a stone and for preventing new ones. The goal is to produce at least 2.5 liters of urine per day, which generally means drinking about 3 liters of fluid. Water is ideal. That volume keeps urine dilute enough to reduce the chances of crystals forming and helps push a stone through more quickly.
If your urine is pale yellow or nearly clear, you’re in the right range. Dark yellow means you need more. Spread your intake across the day, including before bed, since urine concentrates overnight.
Medications That Help Stones Pass
Your doctor may prescribe a medication that relaxes the muscles in your ureter, making it easier for the stone to slide through. Tamsulosin is the most commonly used option. A systematic review of multiple trials found that patients taking tamsulosin had an 85% stone passage rate compared to 66% for those on placebo, a meaningful 17-percentage-point improvement.
This benefit was strongest for larger stones (roughly 5 mm and above). For very small stones that are likely to pass quickly on their own, the medication may not add much. Your doctor will factor in your stone’s size and location when deciding whether to prescribe it.
What Determines Whether a Stone Will Pass
Size is the biggest predictor. Research using CT imaging found these spontaneous passage rates:
- 1 mm: 87% pass on their own
- 2 to 4 mm: 76% pass, averaging about 31 days
- 5 to 7 mm: 60% pass, averaging about 45 days
- 7 to 9 mm: 48% pass
- Larger than 9 mm: 25% pass, and the timeline stretches to months
Location matters too. A stone sitting near the bladder end of the ureter has about a 79% chance of passing on its own, while one still close to the kidney passes without help only about 48% of the time. As the stone travels lower, the ureter widens slightly and the odds improve.
When You Need a Procedure
If a stone is too large to pass, causes an infection, or blocks urine flow for too long, your doctor will recommend removing it. Three main approaches exist, and the choice depends on stone size, location, and composition.
Shock wave lithotripsy uses focused sound waves from outside the body to break a stone into smaller fragments you can then pass naturally. It’s noninvasive and works best for stones smaller than 2 cm in the kidney or upper ureter. For harder stones in the lower part of the kidney, however, the success rate drops to around 62%.
Ureteroscopy involves threading a thin scope through the bladder and up the ureter to reach the stone directly. The doctor can break it apart with a laser and remove the fragments. This approach achieves stone-free rates above 90% for moderate-sized stones and carries fewer complications than more invasive options. It’s often the preferred method for stones in the ureter or lower kidney.
Percutaneous nephrolithotomy is reserved for large stones (generally over 2 cm) or complex cases. A small incision in your back gives the surgeon direct access to the kidney. Recovery takes longer, but it’s the most effective option for big stones that other methods can’t handle.
How Stones Are Diagnosed
If you show up with sudden, severe flank pain, a non-contrast CT scan is the gold standard for confirming a kidney stone. It picks up stones with about 97% sensitivity and 95% specificity, meaning it rarely misses one and rarely flags something that isn’t there. It also reveals the stone’s exact size and position, which directly determines your treatment plan.
Ultrasound is sometimes used instead, particularly for pregnant women or when avoiding radiation is important. It detects signs of blockage (like a swollen kidney) with high accuracy, but it catches only 24% to 57% of stones directly, especially missing smaller ones. If your ultrasound is inconclusive but symptoms point strongly to a stone, a CT scan is usually the next step.
Dietary Changes to Prevent New Stones
About half of people who form a kidney stone will form another within five to ten years, so prevention matters. The specifics depend on your stone type, but most stones are calcium oxalate, and the dietary principles for those are well established.
The American Urological Association recommends that calcium stone formers consume 1,000 to 1,200 mg of dietary calcium per day. This sounds counterintuitive, but calcium from food binds to oxalate in your gut and prevents it from reaching your kidneys. Cutting calcium actually increases stone risk. Get your calcium from food rather than supplements, and eat it alongside meals that contain oxalate-rich foods.
Speaking of oxalate, the foods highest in it are spinach, rhubarb, nuts, peanuts, and wheat bran. You don’t need to eliminate these entirely, but if you’ve had calcium oxalate stones, reducing your portions of these specific foods can lower the oxalate concentration in your urine. Limiting sodium is also important, since high salt intake forces your kidneys to excrete more calcium. The AUA specifically advises reducing sodium for people with high urinary calcium levels.
Do Citrus Juices Help?
Citrate in urine inhibits stone formation, so raising your citrate levels is a legitimate prevention strategy. Citrus juices can do this, but not all citrus is equal. Ten clinical studies found that orange, grapefruit, and lemon juices all increased urinary citrate levels. However, orange juice had the strongest alkalinizing effect on urine, while lemon juice raised citrate but did not significantly change urine pH. One study found that lemonade didn’t increase urinary citrate or pH at all.
The difference comes down to chemistry: citrate in oranges pairs with potassium, which supports the alkalinizing effect, while citrate in lemons pairs with hydrogen ions that neutralize it. If you’re choosing between the two for stone prevention, orange juice has the edge, though it also slightly increases urinary oxalate. Your doctor may prescribe potassium citrate supplements instead, which provide a more reliable and measurable dose than any juice.