How painful is it to pass kidney stones? What the ER doctors won’t tell you

It starts as a dull ache. Maybe you think you pulled a muscle at the gym or slept funny on your side. Then, within twenty minutes, it feels like a hot poker is being twisted into your flank. You’re pacing. You’re sweating. You’re probably on the bathroom floor wondering if your appendix just exploded. This is the reality of renal colic. If you’ve ever wondered how painful is it to pass kidney stones, the answer isn't just "very." It’s a primal, visceral type of agony that frequently gets compared to childbirth or being stabbed from the inside out.

Honestly, the pain isn't even the worst part for some people. It’s the unpredictability. One minute you’re fine, and the next, you’re projectile vomiting because the pain is so intense your brain literally can't process the signals.

The biology of why it hurts so bad

Most people think the pain comes from the stone scratching the inside of the ureter. While that "shards of glass" feeling is definitely part of the experience, it’s not the primary cause of that soul-crushing ache in your back. The real culprit is pressure. When a stone—even a tiny 2mm one—gets stuck in the ureter, it acts like a dam. Your kidney keeps producing urine because that’s its job.

Since the urine has nowhere to go, it backs up. This causes the kidney to swell, stretching the renal capsule. That capsule is packed with sensitive nerve endings. When it stretches, it sends a frantic SOS to your brain. This is why the pain often comes in waves (paroxysms). The ureter is essentially a muscular tube trying to squeeze the stone out through peristalsis. Every time it contracts to push, you feel that spike of "get me to the hospital now" pain.

There is a specific medical scale often used, though it's subjective. Many urologists, including those at the Mayo Clinic, note that patients consistently rank kidney stone pain as a 9 or 10 out of 10.

The "Staircase" of Agony

It’s rarely a constant throb. Instead, it’s a staircase.

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1. The dull build-up in the lower back or side.
2. The "Point of No Return" where over-the-counter meds do absolutely nothing.
3. The "Peaking" phase where you can't find a comfortable position. You’ll sit, stand, kneel, and lie down all within sixty seconds.
4. The "Referred Pain" stage. This is where it gets weird. As the stone moves lower toward the bladder, the pain shifts. For men, it might migrate into the testicles. For women, it hits the labia. It’s a cruel trick of the nervous system.

Size doesn't always matter (but it kind of does)

There’s a common misconception that a bigger stone equals more pain. Not necessarily. A jagged, 3mm calcium oxalate stone can be significantly more painful than a smooth 6mm stone if the smaller one has sharp "wings" that snag on the ureter wall.

However, size is the "deciding factor" for whether you can actually pass it. Generally, stones smaller than 4mm have an 80% chance of passing on their own. Once you hit 6mm, those odds drop to about 50%. If you’re rocking a 10mm "staghorn" stone, you aren't passing that. You’re looking at lithotripsy or surgery.

Dr. Brian Eisner, a urologist at Massachusetts General Hospital, often points out that the narrowest part of the journey is the ureterovesical junction—where the tube meets the bladder. If you can make it past that "gatekeeper," the hardest part is over. Passing it out of the bladder through the urethra is usually a breeze compared to the trek down the ureter.

What it actually feels like: Real patient perspectives

If you ask ten people how painful is it to pass kidney stones, you'll get ten slightly different horror stories. One patient described it as "having a slow-motion lightning bolt trapped in my groin." Another compared it to the sensation of a "serrated knife being dragged through my innards every time I took a breath."

It’s also an exhausting pain. It’s fatiguing. After four or five hours of intense renal colic, your body is physically spent. You’re dehydrated from vomiting and shaking from the adrenaline dump.

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The Nausea Factor

Why do you throw up? It seems unrelated, right? It’s actually because the kidneys and the gastrointestinal tract share the same nerve pathways. When the kidney is in crisis, the signals get crossed, and your stomach decides to evacuate everything. It’s a systemic "red alert" that shuts down non-essential functions.

Can you make it hurt less?

If you’re in the middle of an attack right now, reading this might be difficult. But there are clinical ways to manage the "how painful" aspect.

• Alpha-Blockers: Drugs like Tamsulosin (Flomax) are often prescribed. They don't kill the pain directly, but they relax the muscles in your ureter. It’s like widening the hallway so the stone can slide through easier.
• NSAIDs vs. Opioids: Surprisingly, many studies show that high-dose NSAIDs (like Ketorolac/Toradol) are more effective for kidney stone pain than morphine. Why? Because NSAIDs reduce the inflammation and the pressure inside the kidney, attacking the source of the pain rather than just masking it.
• The "Jump and Bump" Method: This is more of a "folk" remedy that some swear by. The idea is to drink a ton of water and then literally jump or go for a bumpy car ride to help gravity move the stone. It’s not exactly scientific, but when you’re desperate, you’ll try anything.

When to stop toughing it out

There is a point where "how painful is it" becomes "how dangerous is it." You should never try to "white knuckle" a stone if you have a fever or chills. That’s a sign of an infection trapped behind the stone. This is a medical emergency called urosepsis. If you can't keep fluids down because of the vomiting, you need an IV. Dehydration makes the stones harder to pass because your urine flow—the very thing meant to push the stone—dries up.

Why some people are "Stone Formers"

If you’ve had one, you have a 50% chance of getting another within five years. It’s a bleak statistic.

Diet plays a massive role. Most stones are made of calcium oxalate. If you’re chugging spinach smoothies and eating handfuls of almonds while staying dehydrated, you’re basically a stone factory. Paradoxically, you need more dietary calcium to bind with oxalate in your gut so it doesn't end up in your kidneys.

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Also, watch the salt. Sodium forces more calcium into your urine. It’s a chemical chain reaction that ends with you screaming in an ER waiting room at 3:00 AM.

Actionable Steps for the Painful Journey Ahead

If you suspect a stone is on the move, stop waiting for it to "just go away."

1. Hydrate, but don't overdo it: Chugging three gallons of water won't "flush" it faster if it's stuck; it might just increase the pressure and the pain. Aim for consistent, steady sips.
2. The Strainer is your best friend: It sounds gross, but you need to catch the stone. If the lab can analyze it, they can tell you exactly why you made it. Was it uric acid? Calcium? Cystine? This is the only way to prevent the next one.
3. Heat is underrated: A heating pad on your flank or a very hot shower can sometimes help relax the spasms. It’s a small comfort, but in the world of kidney stones, small comforts are everything.
4. Ask for a CT scan: Don't let a doctor guess based on your symptoms. A non-contrast CT is the gold standard for seeing exactly where that stone is and how big it is. If it’s 9mm, you can stop "waiting" and start scheduling a procedure.
5. Citric Acid is a shield: Long-term, adding lemon juice to your water can help. Citrate binds with calcium and prevents it from forming those painful crystals in the first place.

Passing a stone is a marathon of endurance. It tests your pain tolerance in ways few other things can. But knowing why it hurts—and that the pain will end the moment that stone drops into the bladder—can sometimes help you get through the worst of the waves. Keep your fluids up, watch for fever, and don't be a hero when it comes to pain management.

Next Steps for Recovery: Once the stone passes, the relief is almost instantaneous. However, your work isn't done. Schedule a follow-up with a urologist for a 24-hour urine collection test. This will measure your volume, pH, and mineral levels to create a specific roadmap for prevention. If you don't change the underlying chemistry of your urine, you’re likely to repeat this painful cycle within a few years. Ensure you keep the stone you passed for chemical analysis; it is the most valuable piece of evidence for your future health.