Kidney stones are widely considered one of the most painful experiences a person can have without surgery, and the reputation is earned. The pain can be sudden, severe, and debilitating, sometimes compared to childbirth or a broken bone. But “how bad” kidney stones are depends on more than just the pain of passing one. Stone size, location, and whether complications develop all shape the experience, and for many people, the real problem is that stones tend to come back.
What the Pain Actually Feels Like
A kidney stone doesn’t hurt because of its size alone. The pain comes from the stone moving into the ureter, the narrow tube connecting your kidney to your bladder. When a stone gets stuck or slowly works its way through, it causes the ureter to spasm and the kidney to swell with backed-up urine. This produces intense, wave-like pain that typically hits in your side or lower back and can radiate to your groin or lower abdomen.
These waves of pain, called renal colic, often come and go in cycles lasting 20 to 60 minutes. Between episodes you might feel relatively fine, only to be hit again. Many people also experience nausea, vomiting, and an urgent need to urinate even when very little comes out. The pain can be severe enough that sitting still or finding a comfortable position becomes impossible.
Size Determines Whether You’ll Pass It
Not every kidney stone requires a procedure. Smaller stones often pass on their own, though “on their own” still means days or weeks of discomfort. Research published in the American Journal of Roentgenology tracked spontaneous passage rates by stone size, and the numbers drop sharply as stones get bigger:
- 1 to 4 mm: About 72% to 87% pass without intervention.
- 5 to 6 mm: Around 60% to 72% pass, though this range is where many people need medical help.
- 7 to 9 mm: Only 33% to 56% pass on their own.
- 10 mm or larger: Roughly 25% to 27% pass spontaneously, and most require a procedure.
Stones under 5 mm are the ones most commonly managed at home with pain medication, fluids, and time. Once a stone reaches 6 or 7 mm, the odds of needing intervention climb significantly. Your doctor will typically use a CT scan to measure the stone and decide whether watchful waiting makes sense or whether it’s time for a procedure.
When Stones Become Dangerous
Pain aside, kidney stones can cause real medical harm if they block urine flow for too long. A stone lodged in the ureter can cause hydronephrosis, a condition where the kidney swells because urine can’t drain. According to the Cleveland Clinic, severe or prolonged hydronephrosis can permanently damage the kidney and, in the worst cases, lead to kidney failure requiring dialysis or transplant.
Trapped urine also creates an ideal environment for bacteria. Urinary tract infections that develop behind an obstructing stone can escalate quickly into a kidney infection or even sepsis, a life-threatening response to infection that requires emergency treatment. This is why a kidney stone accompanied by fever and chills is treated as an urgent situation, not just a painful one.
The Mayo Clinic identifies several warning signs that call for immediate medical attention: pain so severe you can’t sit still, pain with nausea and vomiting, fever and chills alongside stone symptoms, visible blood in your urine, or difficulty urinating. Any of these combinations suggests the stone is causing more than pain.
What Happens If You Need a Procedure
Two common approaches are used for stones that won’t pass. Shockwave lithotripsy uses focused sound waves from outside the body to break the stone into smaller pieces that can then pass naturally. It’s noninvasive and typically involves a short hospital stay of about half a day. The trade-off is a lower success rate: roughly 64% of patients are stone-free afterward.
Ureteroscopy involves passing a thin, flexible scope through the urethra and bladder up to the stone, where it’s broken apart with a laser and the fragments are removed. This approach has a higher stone-free rate of about 78%, but it requires anesthesia, takes longer in the operating room, and involves an average hospital stay of about one day. Some patients have a temporary stent placed in the ureter afterward, which can cause its own discomfort for a week or two.
Neither procedure is particularly grueling in terms of recovery. Most people return to normal activities within a few days to a week, though soreness and blood in the urine are common in the short term.
The Toll Beyond Physical Pain
Kidney stones don’t just hurt in the moment. A study in The Journal of Urology found that stone patients scored lower than the average American population in five of eight quality-of-life measures, including physical functioning and energy levels. People dealing with kidney stones reported missing an average of 10 workdays, with some losing up to a full year of work depending on complications and recurrence. The more workdays missed, the lower patients scored on measures of energy and fatigue, suggesting a cycle where stones drain both physical health and daily functioning.
There’s also the psychological weight. Living with the knowledge that another stone could form at any time creates a background anxiety that many patients describe as nearly as burdensome as the pain itself.
Recurrence Is the Real Problem
Perhaps the most frustrating aspect of kidney stones is how often they come back. Adults who experience a first symptomatic stone have a 50% chance of recurrence within the next 5 to 10 years. That’s a coin flip, and the odds get worse with each subsequent stone if the underlying causes aren’t addressed.
The most effective way to reduce recurrence is increasing fluid intake enough to produce at least 2 to 2.5 liters of urine per day, which for most people means drinking noticeably more water than feels natural. Dietary changes depend on the type of stone you form. Calcium oxalate stones, the most common type, are influenced by sodium intake, animal protein, and foods high in oxalate like spinach, nuts, and chocolate. A 24-hour urine collection can identify your specific risk factors and guide targeted prevention.
Kidney stones range from a painful but brief inconvenience to a recurring condition that affects your kidneys, your work, and your overall well-being. How bad they are for you depends largely on how big the stone is, whether it causes obstruction, and whether you take steps to prevent the next one.