The Truth About Kidney Stones: How to Prevent Them From Coming Back
Kidney stones send more than half a million Americans to the emergency room every year. They’re one of the most painful experiences in medicine. And for roughly half the people who get one, it will happen again — usually within five years. What’s surprising isn’t that recurrence is so common. It’s that most of it is preventable, and most patients are never told how.
That last part is what bothers me. The information exists. The testing exists. The interventions work. But somewhere between the ER discharge and the follow-up that never gets scheduled, people fall through the cracks — and they show up again with another stone, more pain, and the same unanswered question: why does this keep happening to me?
Let me try to answer that.
Why Stones Come Back
Before we talk prevention, it helps to understand why stones form in the first place. Most kidney stones — somewhere around 80 percent — are made of calcium oxalate. That doesn’t mean you’re eating too much calcium. In fact, cutting calcium from your diet often makes things worse, not better.
What usually drives stone formation is a combination of factors: concentrated urine, too much of certain minerals being filtered through the kidneys, not enough fluid intake, diet habits, and sometimes underlying metabolic conditions that fly under the radar for years.
The reason I bring this up is that generic advice — “drink more water, eat less salt” — misses a big part of the picture. What works for one patient may not work for another, because not all stones are the same and not all bodies process minerals the same way.
Step One: Find Out What Kind of Stone You Had
If you passed a stone and saved it — good. If you didn’t, that’s okay too, but it does make prevention a little more like guesswork.
Stone analysis gives us real information. Calcium oxalate stones, uric acid stones, struvite stones, and cystine stones each have different causes and respond to different interventions. A uric acid stone, for example, is often tied to diet and can sometimes be dissolved with medication and hydration. A struvite stone, on the other hand, is typically linked to a bacterial infection and needs a completely different approach.
When I see a patient who has had a stone — especially a second one — I also recommend a 24-hour urine collection. It sounds tedious, and honestly, it is. But what it tells us is invaluable: how much calcium, oxalate, uric acid, citrate, and other key compounds your kidneys are actually excreting over the course of a day. That data shapes a prevention plan that’s specific to you, not just a general pamphlet.
Hydration: The Part Everyone Thinks They're Already Doing
Almost every patient I ask tells me they drink “plenty of water.” Then I ask them to tell me exactly how much, and the number is usually far less than they think.
The goal for most stone formers is to produce at least two to two and a half liters of urine per day. To get there, most people need to drink somewhere between two and three liters of fluid — and that number goes up if you live somewhere hot, exercise regularly, or spend a lot of time outdoors. Los Angeles summers don’t help.
The color of your urine is a reasonable real-world guide: pale yellow is where you want to be. Dark yellow or amber means you’re behind on fluids and your urine is concentrated — exactly the environment where crystals start to form.
One thing I do recommend avoiding: drinking large amounts of fluid all at once and then going hours without drinking anything. Consistency matters more than volume in a single sitting. Keep a water bottle with you and sip throughout the day
Diet Changes That Actually Matter
Salt is a bigger problem than most people realize. High sodium intake causes the kidneys to excrete more calcium into the urine. More calcium in the urine means a higher risk of calcium-based stones. Processed foods, canned soups, deli meats, and restaurant meals are often loaded with sodium even when they don’t taste especially salty. Reading labels is worth the effort.
Don’t cut calcium — pair it correctly. This one surprises people. Dietary calcium, when eaten with meals, binds to oxalate in the gut and helps prevent it from being absorbed and sent to the kidneys. When you eat a low-calcium diet, more oxalate reaches the kidneys on its own. The trouble comes from calcium supplements taken without food — those can raise urinary calcium without the benefit of binding oxalate in the digestive tract.
Oxalate awareness, not obsession. If you’ve had calcium oxalate stones, some awareness of high-oxalate foods makes sense. Spinach, beets, nuts, and chocolate are among the highest. I’m not telling my patients to never eat spinach again — that’s unrealistic and honestly overkill for most people. But having a large spinach smoothie every single morning? That’s worth reconsidering.
Animal protein and uric acid stones. Diets heavy in red meat, shellfish, and organ meats raise uric acid levels in the urine. If your stones are uric acid-based or if your 24-hour urine shows high uric acid, moderating animal protein and possibly adjusting your urine pH with medication can make a real difference.
When Medication Comes Into the Picture
For some patients, diet and hydration alone don’t move the needle enough, and medication becomes part of the plan. This isn’t a failure — it’s just biology.
Thiazide diuretics can reduce the amount of calcium the kidneys excrete. Potassium citrate raises urinary citrate levels, which helps prevent crystals from forming and sticking together. Allopurinol is sometimes used when uric acid production is the main driver.
Whether any of these make sense for a given patient depends on what their stone analysis and 24-hour urine results show. I don’t prescribe them routinely — I prescribe them when the data supports it.
The Follow-Up Piece Nobody Wants to Skip
Stone prevention isn’t a one-time conversation. I want to see my stone formers back, and I want to repeat that 24-hour urine collection after they’ve had time to make changes. Sometimes what we thought was the right intervention doesn’t move the numbers the way we expected, and we need to adjust.
Imaging also plays a role. A KUB X-ray or ultrasound periodically lets us check whether new stones are forming before they cause a problem. Finding a small stone that hasn’t passed yet gives us the opportunity to be proactive rather than reactive.
A Word on Why This Matters Beyond the Pain
Kidney stones are painful — anyone who’s had one can confirm that — but the reason I take prevention seriously goes beyond comfort. Recurrent stone disease can cause lasting damage to kidney function over time. Obstruction, infection, and repeated instrumentation each carry their own risks. Getting ahead of this is genuinely worth the effort.
I’ve seen patients completely turn things around with consistent changes. I’ve also seen patients who assumed that one stone was a fluke and found themselves in the emergency room again eighteen months later. The difference often comes down to whether they got the right information and actually followed through on it.
If you’ve had a kidney stone — especially if you’ve had more than one — don’t wait for the next one to take it seriously. Come in, let’s look at what’s driving it, and build a plan that actually makes sense for you.
Dr. Leonard W. Liang is a board-eligible urologist practicing in Downtown Los Angeles. He trained at the University of Michigan, completed his urology residency at Kaiser Permanente Los Angeles, and served a two-year kidney transplant fellowship at UCLA. He currently sees patients at 1513 S Grand Ave, Suite 300, Los Angeles, CA 90015. To schedule an appointment, call 213-749-0662.
