Kidney stone pain typically starts in your side and back, just below the ribs, at a spot called the costovertebral angle. From there it radiates forward and downward toward the lower abdomen and groin. The exact location shifts as the stone moves through your urinary tract, which is why the pain can feel like a moving target.
Where the Pain Starts
The initial pain hits in the flank, the area between your lower ribs and hip on the affected side. This is where the kidney sits, and when a stone blocks the flow of urine, pressure builds rapidly. The result is a sudden, severe pain that many people describe as the worst they’ve ever felt. It’s not a dull ache at first. It comes on fast and sharp.
The pain is one-sided. A stone in your left kidney causes left flank pain; a stone in the right kidney causes right flank pain. It doesn’t cross the midline, so if you feel it on both sides simultaneously, something else is likely going on.
How Pain Moves as the Stone Moves
A kidney stone doesn’t stay in one place, and neither does the pain. The stone travels from the kidney through the ureter (the narrow tube connecting the kidney to the bladder), then into the bladder, and finally out through the urethra. At each stage, the pain shifts.
When the stone is in the upper ureter, near the kidney, the pain is mostly in the flank and back. As it moves into the middle ureter, the pain tends to wrap around toward the front of the abdomen. Once the stone reaches the lower ureter, closer to the bladder, the pain migrates down into the lower abdomen and groin. This downward progression can happen over hours or days, depending on the size of the stone and how quickly it moves.
Pain intensity also fluctuates. It often comes in waves, building to a peak and then easing before surging again. These waves correspond to the ureter squeezing and relaxing as it tries to push the stone along. Between waves you might feel almost normal, only to be hit again minutes later.
Pain Differences Between Men and Women
For most of the stone’s journey, men and women feel it in the same places. The difference shows up when the stone reaches the lower ureter near the bladder. In men, the pain can extend into the groin or scrotum, and some men report a stinging sensation at the tip of the penis. In women, the pain can radiate to the labia and may feel similar to a menstrual cramp.
These referred pain patterns happen because the nerves serving the lower ureter overlap with nerves supplying the reproductive organs. Your brain interprets the signals as coming from both areas at once.
Symptoms That Come With the Pain
Pain is rarely the only symptom. Most people also experience nausea or vomiting, triggered by the intensity of the pain and shared nerve pathways between the kidney and the gut. Blood in the urine is common as the rough stone scrapes the lining of the ureter. Your urine may look pink, red, or brown.
As the stone nears the bladder, urinary symptoms ramp up. You may feel an urgent need to urinate, need to go more frequently, or feel burning during urination. Some people pass only small amounts despite feeling like their bladder is full. These symptoms are easy to mistake for a urinary tract infection, especially in women.
What Kidney Stone Pain Doesn’t Feel Like
Kidney stone pain has a few hallmarks that help distinguish it from other conditions. It’s almost impossible to get comfortable. Unlike muscle pain or back strain, changing positions doesn’t relieve it. People with kidney stones are often restless, pacing or shifting constantly, which is the opposite of someone with appendicitis or peritonitis, who tends to lie very still.
The colicky, wave-like pattern also sets it apart. A steady, constant ache in the flank is less likely to be a passing stone and more likely to point toward infection, a tumor, or another kidney problem. Renal infections tend to come on more gradually and are usually accompanied by fever and chills. A dull, persistent flank pain could also signal a congenital obstruction, a stricture from previous surgery, or even a condition outside the urinary tract entirely, since problems in the chest, spine, or abdomen can refer pain to the flank.
How Stones Are Located
When you show up with classic flank-to-groin pain, imaging confirms where the stone is and how big it is. A CT scan without contrast is the most common initial test because of its high sensitivity for detecting stones anywhere in the urinary tract. It also reveals how much the ureter is blocked and whether complications like swelling of the kidney are developing. Ultrasound is sometimes used as a first step, particularly in pregnant women or when avoiding radiation exposure is a priority.
The stone’s location on imaging directly predicts what happens next. Stones in the lower ureter, close to the bladder, are the most likely to pass on their own. Stones lodged higher up or larger than about 6 millimeters are less likely to pass without intervention.
Left Side vs. Right Side Pain
Right-sided kidney stone pain deserves a specific mention because it overlaps with appendicitis. Both can cause right lower abdominal pain, nausea, and restlessness. The key difference is that kidney stone pain usually starts in the back and radiates forward, while appendicitis pain classically starts around the belly button and moves to the lower right abdomen. Blood in the urine strongly suggests a stone rather than appendicitis, but imaging is often needed to tell them apart definitively.
On the left side, the main condition that mimics kidney stone pain is diverticulitis, which causes left lower abdominal pain, sometimes with fever and changes in bowel habits. Again, the flank origin and urinary symptoms of a kidney stone help distinguish the two, but overlap exists.