Kidney stones are one of the most painful conditions a person can experience. On a 0-to-100 pain scale, patients with active kidney stone episodes average a score of about 73, and nearly 89% of men who have had one describe it as the worst pain of their lives. The pain is often compared to childbirth, and for good reason: in a study of women who had experienced both, 63% said their kidney stone was actually more painful than giving birth.
What the Pain Feels Like
Kidney stone pain isn’t one consistent sensation. It has two distinct components that can overlap. The first is a deep, dull ache caused by the stone blocking urine flow. When a stone lodges in the narrow tube connecting the kidney to the bladder, urine backs up and stretches the kidney’s outer capsule. That stretching produces a constant, heavy pressure deep in your back or side, just below the ribs.
The second component is sharper and more intense: waves of spasmodic pain caused by the muscular walls of the ureter clenching and squeezing, trying to push the stone downward. These waves hit hard, peak for minutes, then briefly ease before returning. Many people describe them as stabbing or cramping sensations that make it impossible to find a comfortable position. Nausea and vomiting are common during the worst waves.
Where you feel the pain depends on where the stone is at that moment. A stone still near the kidney produces pain in the flank and back. As it moves lower through the ureter, the pain tends to migrate toward the lower abdomen and groin. Some people also feel an urgent, burning need to urinate when the stone reaches the section of the ureter closest to the bladder.
How Long an Episode Lasts
A kidney stone pain episode follows a roughly predictable pattern with three phases: onset, peak, and relief. In the first phase, pain builds steadily and typically reaches its maximum intensity within one to two hours, though it can take up to six hours in some cases. Once it peaks, the pain enters a sustained phase where it holds at maximum intensity. This plateau usually lasts one to four hours but can persist beyond 12 hours. The entire episode, from the first twinge to meaningful relief, generally spans 3 to 18 hours.
These episodes can recur multiple times over days or weeks as the stone gradually works its way down. Each time the stone shifts position or gets temporarily stuck, another round of intense pain can start. Between episodes, you might feel fine or have only mild discomfort, which makes the sudden return of severe pain all the more jarring.
Stone Size Doesn’t Predict Pain
One of the most counterintuitive facts about kidney stones is that bigger stones don’t necessarily hurt more. A study of 650 patients published in The Journal of Urology found no association between stone size, stone location, and how much pain patients reported. A tiny 2-millimeter stone can cause the same agonizing episode as a larger one. The pain has more to do with how much the stone obstructs urine flow and how aggressively the ureter spasms in response than with the stone’s physical dimensions. This means you can’t gauge the seriousness of a stone by how much it hurts, and a small stone is no guarantee of mild symptoms.
How It Compares to Other Pain
Kidney stone pain regularly appears on lists of the most severe pain humans experience, alongside childbirth, cluster headaches, and severe burns. A study conducted across two hospitals in the UK put numbers to the comparison. Researchers asked patients experiencing kidney stone episodes to rate their pain, then asked women in the group who had also given birth to compare the two. Nearly two-thirds of those women said the kidney stone hurt more than labor. Another 16% said the pain was comparable, and only about 21% rated childbirth as worse.
Interestingly, men tended to underestimate their own experience. About 40% of male patients assumed their kidney stone pain was probably less severe than childbirth, even though almost 9 out of 10 of them said it was the worst pain they had ever felt. The data suggests that kidney stone pain deserves its fearsome reputation.
How the Pain Is Treated
Anti-inflammatory pain relievers are the first-line treatment for kidney stone pain because they target the specific mechanism causing it. The ureter produces inflammation-signaling chemicals when a stone irritates its walls, and anti-inflammatories block that process directly. A meta-analysis covering nearly 2,000 patients found these medications reduce pain about as effectively as stronger narcotic painkillers within the first 30 minutes, with fewer side effects. Patients given anti-inflammatories were significantly less likely to vomit and less likely to need additional rescue medication compared to those given opioid-based painkillers.
For stones that need help passing, doctors sometimes prescribe a medication that relaxes the smooth muscle of the ureter, making it easier for the stone to move through. In clinical trials, patients given this type of medication alongside pain relief saw their pain drop from an average of about 8.7 out of 10 before treatment to roughly 1 out of 10 six hours later. Most of that drop happened within the first 30 minutes to two hours.
Not all stones pass on their own. Stones larger than about 6 millimeters often require a procedure to break them up or remove them. But even for stones that will eventually pass naturally, the primary medical goal is controlling pain while the body does the work.
Warning Signs That Need Immediate Attention
Most kidney stone episodes, while excruciating, resolve without complications. But certain symptoms alongside the pain signal a more dangerous situation. Fever or chills combined with kidney stone pain can indicate an infection trapped behind the blockage, which can become serious quickly. Blood in the urine is common with stones and not always alarming on its own, but if you’re unable to keep fluids down due to vomiting, the risk of dehydration adds urgency. Pain so severe that over-the-counter medication provides no relief, or pain that has persisted and worsened over several hours, also warrants emergency evaluation. A complete inability to urinate is another red flag that the obstruction may need immediate intervention.