Most people who pass a kidney stone are told to drink more water and sent home. About half of them will be back with another stone within ten years.
The second stone is usually preventable. Preventing it takes the one thing the first visit almost never includes: finding out why you made the first one.
I'm a nephrologist, so this is my side of kidney stones. Urologists remove them. My job is making sure you need a urologist as rarely as possible.
What a kidney stone is, briefly
A kidney stone is a hard deposit that forms when urine carries more of a mineral than it can keep dissolved. Crystals form, stick together, and grow. Small ones pass without anyone noticing. Larger ones get stuck in the ureter, the narrow tube between the kidney and the bladder, and that is when the pain starts.
About one in eleven Americans will have a stone at some point. Texas sits in the southern "stone belt," where heat, sweat, and concentrated urine push the numbers higher. Our kidney stones page covers the condition in full. This article is about the part that comes after: keeping it from happening again.
The four main types, and why the type matters
| Type | How common | What drives it | Prevention focus |
|---|---|---|---|
| Calcium oxalate and calcium phosphate | About 4 in 5 stones | Low urine volume, high urine calcium or oxalate, low citrate, too much salt | Fluids, less salt, normal calcium intake, sometimes a thiazide or potassium citrate |
| Uric acid | About 1 in 10 | Acidic urine, gout, diabetes, extra weight, a lot of animal protein | Raise urine pH with potassium citrate, less animal protein |
| Struvite | Up to 1 in 10 | Repeated urinary infections with certain bacteria | Remove the entire stone and prevent infections |
| Cystine | 1 to 2 in 100 | An inherited condition called cystinuria | Very high fluid intake, alkaline urine, specific medication |
The type changes almost everything about prevention. Advice that helps a calcium oxalate stone can do nothing for a uric acid stone.
So if you pass a stone, strain your urine, catch it, and bring it in. If a urologist removed it, ask that it be sent for analysis. A stone in a lab report tells me more than any other single test.
Symptoms, and when it is an emergency
The classic stone attack is sudden, severe pain in the side or back, just below the ribs. It comes in waves and often moves toward the groin as the stone travels. Other common signs:
- Pink, red, or brown urine
- Nausea and vomiting
- A constant urge to urinate, or burning when you go
- Restlessness, because no position helps
Pain in the back is not always the kidney. Our post on back pain vs. kidney pain explains how to tell the difference.
The emergency signs are listed at the end of this article. The most important one: a stone with fever or chills can mean a blocked, infected kidney, which needs drainage the same day.
How kidney stones are diagnosed
During an attack, the standard tests are a urinalysis, which looks for blood and infection, and a low-dose CT scan without contrast, which shows the stone's size and location. Ultrasound is used in pregnancy and to limit radiation on repeat checks.
After the stone has passed or been removed, the prevention workup begins. This is the part most people never get:
- Stone analysis , to identify the type.
- Blood tests for calcium, uric acid, kidney function, bicarbonate, and potassium, plus parathyroid hormone if calcium runs high.
- A 24-hour urine collection. This measures exactly what your kidneys are putting out: urine volume, calcium, oxalate, citrate, uric acid, sodium, and pH. It is the single most useful test in stone prevention.
The American Urological Association recommends this evaluation for anyone with repeat stones and for first-time stone formers at higher risk. I offer it to anyone who would rather not have a second one.
Timing matters. Do the 24-hour urine on an ordinary day, eating and drinking the way you normally do, a few weeks after the stone has passed and not during an infection. A collection taken on your best behavior hides the problem.
Treatment when a stone is stuck
Most stones smaller than about 5 millimeters pass on their own within a few weeks. While you wait, the usual plan is pain control, fluids, and often tamsulosin, a medication that relaxes the ureter and helps larger stones pass. That approach is called medical expulsive therapy.
For stone pain, NSAIDs such as ibuprofen or ketorolac often work as well as opioids. They are not a good choice for people with kidney disease. Our guide to pain relievers that are safe for your kidneys explains why.
Stones that are too big, stuck, or causing infection are removed by a urologist with shock wave lithotripsy, ureteroscopy, or, for very large stones, percutaneous nephrolithotomy through a small opening in the back.
All of those end the episode. None of them changes the chemistry that made the stone. That is the rest of this article.
How to prevent kidney stones from coming back
Drink enough to make 2.5 liters of urine a day
The goal is urine volume, not a number of glasses. For most adults, making about 2.5 liters of urine means drinking close to 3 liters of fluid a day, and more in a Houston summer or with outdoor work.
The simplest system I know: a one-liter bottle, finished three times by early evening. Your urine should look pale yellow all day, not just in the morning.
Water is best. Coffee and tea count, and coffee is linked with fewer stones, not more. Lemon or lime in your water adds a little citrate, which helps. Sugary sodas and large amounts of sweet tea raise stone risk. Beer is not a treatment for stones, despite what your uncle says; our post on alcohol and your kidneys explains why.
Cut the salt
Sodium pulls calcium into the urine. Keeping salt under about 2,300 mg a day is one of the most effective changes a calcium stone former can make. Most of it comes from restaurant food, deli meat, canned soup, frozen meals, and bread, not the salt shaker. The 24-hour urine sodium shows whether it is working.
Do not cut calcium
This is the advice people most often get backward. A low-calcium diet raises the risk of calcium oxalate stones, because calcium in the gut binds oxalate before it can be absorbed.
Aim for about 1,000 to 1,200 mg of calcium a day from food, spread across meals. If you need a calcium supplement, take it with food, not on an empty stomach.
Be smart about oxalate, not obsessive
Oxalate restriction matters most when the 24-hour urine shows high oxalate. The biggest sources are spinach, rhubarb, almonds and other nuts, beets, dark chocolate, and soy. Eating them with a calcium-containing food at the same meal blunts the effect. Our kidney stones page has the details on doing a low-oxalate diet correctly.
Two supplements deserve a warning: high-dose vitamin C turns into oxalate, and turmeric supplements are high in it. More on both in our guide to kidney flushes and supplements.
Ease up on animal protein
Meat, chicken, fish, and eggs raise uric acid and calcium in the urine and lower citrate. You do not need to go vegetarian. Normal portions, more vegetables and fruit, and fewer large meat-heavy meals make a measurable difference. A DASH-style eating pattern, rich in fruits, vegetables, and low-fat dairy, is linked with a lower stone risk.
Lose weight if you carry extra
Extra weight and insulin resistance make urine more acidic, which drives uric acid stones. Gradual weight loss helps. Very low-carb, high-protein diets can raise stone risk, so the method matters.
Medications that prevent kidney stones
When diet and fluids are not enough, or the 24-hour urine shows a specific problem, medication helps. Medication chosen without a 24-hour urine is a guess.
| Medication | Used for | What to know |
|---|---|---|
| Thiazide-type diuretics (hydrochlorothiazide, chlorthalidone, indapamide) | High urine calcium | A large 2023 trial found hydrochlorothiazide did not meaningfully lower recurrence, so these are no longer automatic. I use them for clearly high urine calcium, often when blood pressure also needs treatment, and recheck the urine. They can lower potassium and sodium. |
| Potassium citrate | Low urine citrate, uric acid stones, cystine stones, renal tubular acidosis | Raises urine citrate and pH. Can upset the stomach. Needs care with kidney disease or with ACE inhibitors, ARBs, or spironolactone, because potassium can climb. |
| Allopurinol | High urine uric acid with calcium oxalate stones, or gout | Also the main long-term gout treatment. See how gout is treated. |
| Tiopronin | Cystine stones | Used alongside very high fluid intake and alkaline urine, with regular monitoring. |
| Antibiotics and complete stone removal | Struvite stones | Any fragment left behind can harbor bacteria and regrow the stone. |
Long-term monitoring for recurrent kidney stones
Prevention only works if someone checks whether it is working. A typical follow-up plan for a person who has formed more than one stone:
| When | Test | Why |
|---|---|---|
| After the stone passes | Stone analysis, blood work, 24-hour urine | Find the cause |
| About 6 months after changes | Repeat 24-hour urine and blood work | Confirm the diet or medication actually changed the urine |
| Once a year | 24-hour urine if stable, kidney function and urine albumin | Catch drift before it becomes a stone |
| Every 1 to 2 years, or as advised | Renal ultrasound or low-dose CT | Find stones that are growing silently, before they cause pain |
If you take a thiazide or potassium citrate, add blood work for potassium, sodium, and kidney function a few weeks after starting and at each dose change.
Special considerations
If you have chronic kidney disease
Kidney stones and chronic kidney disease feed each other. Every blockage and procedure can cost some kidney function, and people with recurrent stones are more likely to develop kidney disease over time.
The prevention plan changes too. Fluid targets may need to be lower in advanced kidney disease or heart failure. Potassium citrate can push potassium too high. Thiazides work less well as kidney function falls. NSAIDs for stone pain are risky. The good news: the CT scan used for stones does not need contrast dye.
If you have diabetes
Insulin resistance makes urine more acidic, which is why people with type 2 diabetes form more uric acid stones, often alongside calcium stones. A 2024 study found that people taking SGLT2 inhibitors such as empagliflozin and dapagliflozin had fewer kidney stones than those on some other diabetes drugs. Nobody should start one just for stones, but it is one more reason they fit many people with diabetic kidney disease.
If you have high blood pressure
Stone formers are more likely to develop high blood pressure, and the two share a driver: salt. Cutting sodium helps both. When a patient has high urine calcium and high blood pressure, a thiazide-type diuretic can sometimes treat both at once.
If you have gout or repeated urinary infections
Gout points toward uric acid stones; see our gout page. Repeated urinary infections raise the risk of struvite stones; our post on whether a UTI can go away on its own covers when infections need treatment.
Do you need a nephrologist or a urologist?
Often both, for different jobs. A urologist removes a stone that is stuck. A nephrologist works out why it formed and runs the prevention plan. Our explainer on what a nephrologist does compares the two.
Getting care in Houston
Remix Medical is a physician-owned, multispecialty practice. I see patients for kidney stone prevention in Montrose near the Texas Medical Center, East Houston, Katy, and Groesbeck, and by video visit anywhere in Texas. Reviewing 24-hour urine results and adjusting a plan often works well by video.
You see the same physician at every visit. When stones cause repeated severe pain, our pain management physicians work from the same chart to build a kidney-safe pain plan. When a stone needs to come out, we coordinate with your urologist and pick prevention back up afterward.
Most plans are accepted, including Medicare, Medicare Advantage, and Texas Medicaid. Book an appointment and bring your stone, or its lab report, if you have it.