Kidney stone pain typically starts in the flank, the area on either side of your lower back just below the rib cage. From there, it can shift downward into your lower abdomen or groin as the stone moves through the urinary tract. Where you feel the pain at any given moment depends on where the stone is lodged.
Where the Pain Starts
Because your kidneys sit toward the back of your torso, the initial pain from a kidney stone often feels like it’s deep in your back on one side, tucked under your ribs. Many people mistake it for a pulled muscle or a back injury. This location is typical when a stone is still inside the kidney or has just entered the upper portion of the ureter, the narrow tube that connects the kidney to the bladder.
One reliable way to distinguish this from a muscle problem: kidney pain does not get better or worse when you shift positions. Back pain from a strained muscle or disc issue usually changes with movement. You might find a more comfortable position on the couch. With a kidney stone, no position helps. The pain stays constant or comes in waves regardless of how you sit, stand, or lie down.
How the Pain Moves as the Stone Travels
A kidney stone doesn’t stay in one place. Once it drops into the ureter, the pain tends to migrate downward, following the stone’s path toward the bladder. The classic progression goes like this: flank and back pain shifts to the side of the abdomen, then to the lower abdomen, and finally toward the groin. This migration can happen over hours or days, depending on how quickly the stone moves.
If the stone gets stuck partway down the ureter, it blocks urine flow from that kidney. The resulting backup of pressure is what drives the intense pain. The stone itself is small, but the obstruction it creates is what matters. In fact, research has found no correlation between stone size and pain severity. A tiny stone wedged in a tight spot can produce just as much agony as a larger one.
When the stone reaches the lowest section of the ureter, near where it connects to the bladder, you may start feeling a strong, frequent urge to urinate. You might also feel burning during urination or find that only a small amount comes out each time. These bladder-like symptoms signal that the stone is close to passing. Once it enters the bladder, it typically comes out within a few days, and the pain drops dramatically.
Groin and Genital Pain
One of the more confusing aspects of kidney stone pain is that it can radiate into the groin, inner thigh, or genitals. This is referred pain, meaning the brain interprets signals from the ureter as coming from nearby areas that share the same nerve pathways. The pain can feel like it extends from your side all the way down into the groin.
This referred pain sometimes causes people to worry about a completely different problem, particularly if the flank pain has faded and only the lower symptoms remain. But the pattern of pain that started in the back and migrated downward is a strong indicator that a stone is responsible.
What the Pain Feels Like
Kidney stone pain is sharp and cramping, and it comes in waves. These waves typically last 20 to 60 minutes each, though severe episodes can stretch longer. The pain usually peaks about one to two hours after it first begins, then eases before building again. Between waves, you might feel a dull soreness in the flank or abdomen. During a wave, the pain can be severe enough to make it impossible to sit still. Many people pace, shift around, or curl up trying to find relief.
The wave pattern happens because the ureter is a muscular tube. When a stone blocks it, the ureter squeezes in rhythmic contractions trying to push the stone along. Each contraction produces a surge of pain, followed by a brief lull.
Right Side vs. Left Side
Kidney stones form in one kidney at a time, so the pain is almost always on one side only. A stone in the right kidney produces right-sided flank and abdominal pain, and a stone in the left kidney produces left-sided pain. This one-sided quality is helpful for distinguishing it from conditions that cause pain across the whole abdomen.
Right-sided kidney stone pain does overlap with appendicitis, which also causes pain on the right side of the lower abdomen. The key differences: appendicitis causes nausea far more often (roughly 80% of cases compared to about 11% with kidney stones), tends to produce fever, and centers on a specific spot in the lower right abdomen. Kidney stone pain, by contrast, usually has a clear starting point in the back and migrates downward. Blood visible in the urine is present in about 92% of ureteral stones and is a strong distinguishing clue.
How to Tell It Apart From Back Pain
The location of kidney stone pain overlaps with ordinary lower back pain, which is why the two get confused so often. A few features set kidney pain apart:
- Response to movement: Muscle or disc pain changes when you shift positions. Kidney stone pain does not improve or worsen with movement.
- Location: Kidney pain sits higher, in the flank beneath the ribs and above the hips. Musculoskeletal back pain often centers lower, near the belt line or lumbar spine.
- Onset: Kidney stone pain usually starts suddenly and intensely. Back strain tends to build gradually or follow a specific injury or activity.
- Associated symptoms: Nausea, vomiting, blood in the urine, or pain that radiates to the groin all point toward a kidney stone rather than a back problem.
Warning Signs That Need Urgent Attention
Most kidney stones pass on their own, but certain symptoms indicate a more serious situation. Fever and chills alongside kidney stone pain raise concern for an infection behind the blockage. An infected, obstructed kidney can escalate quickly, and this combination requires urgent treatment regardless of the stone’s size. Inability to keep fluids down due to persistent vomiting, complete inability to urinate, or pain so severe that over-the-counter medication provides no relief are also reasons to seek immediate care.