Passing a kidney stone typically feels like intense, wave-like pain that starts in your lower back and shifts downward as the stone moves through your urinary tract. The pain comes from the stone squeezing through the ureter, a narrow tube connecting your kidney to your bladder. Most people describe it as one of the worst pains they’ve experienced, though the sensation changes significantly depending on where the stone is in its journey.
Where the Pain Starts
The first sign is usually a sudden, sharp pain in your flank, the area on either side of your lower back just below your ribs. This happens when a stone is still in the kidney or has just entered the top of the ureter. The pain can be constant and dull, or it can hit in sharp waves that last anywhere from 20 to 60 minutes before easing off temporarily. Many people feel it radiate into the back, the side of the abdomen, or both at the same time.
This stage often catches people off guard. The pain can start in the middle of the night or during an ordinary afternoon with no warning. Along with the flank pain, you may feel nauseous or actually vomit. That nausea isn’t from your stomach. It’s a reflex triggered by the intense signals your ureter sends to your nervous system as it spasms around the stone.
How Pain Shifts as the Stone Moves
As the stone works its way down the ureter, the location of your pain moves with it, almost like a tracker. When the stone reaches the middle section of the ureter, the pain tends to shift toward the lower abdomen. When it approaches the bladder, you’ll often feel it in the groin or pelvic area. Men sometimes feel pain in the testicles at this stage; women may feel a deep ache in the pelvis.
This migration of pain is actually useful information. Groin or pelvic pain typically means the stone is in the lower ureter and getting closer to the bladder. That said, this final stretch can still produce severe pain. The lower ureter narrows at the point where it connects to the bladder, so some people find this stage the most intense even though the finish line is close.
The Relief When It Reaches the Bladder
Once the stone drops out of the ureter and into the bladder, the pain usually subsides almost immediately. This moment feels dramatic because you go from significant distress to near-complete relief in a short window. The bladder is much wider than the ureter, so the stone is no longer stretching or blocking a tight tube.
You’re not done yet, though. The stone still needs to leave your body through the urethra when you urinate. Fortunately, the urethra is wider than the ureter, so passing the stone out of your body is far less painful than the journey to the bladder. Some people feel a brief sting or pressure as it exits. Others barely notice it. Once the stone reaches the bladder, it typically passes within a few days.
Other Symptoms Beyond Pain
Pain dominates the experience, but it’s rarely the only symptom. Blood in your urine is common, sometimes visible as a pink or reddish tint, sometimes only detectable on a lab test. The stone scrapes the lining of the ureter as it moves, which causes the bleeding. It looks alarming but is a normal part of the process.
You may also feel a constant, urgent need to urinate, even when your bladder isn’t full. This is especially common as the stone reaches the lower ureter near the bladder, because the irritation tricks your body into thinking it needs to go. Actual urine output during these episodes is often very small. Nausea, vomiting, and bladder pressure round out the typical symptom picture. Fever and chills can occur if an infection develops alongside the stone, which is a sign you need medical attention promptly.
How Long the Whole Process Takes
The timeline depends heavily on the size of the stone. A stone smaller than 4 millimeters (roughly the width of a small pea) may pass on its own within one to two weeks. Larger stones can take two to three weeks, and some take even longer. If a stone hasn’t passed within four to six weeks, follow-up with a provider is important because the stone may be stuck.
Size also determines whether the stone will pass at all without help. Stones 3 millimeters or smaller pass on their own about 98% of the time. At 5 millimeters, that rate drops to around 65%. At 6.5 millimeters or larger, only about 9% pass spontaneously, meaning most stones that size will need a procedure to break them up or remove them.
The pain isn’t constant for the entire timeline. You’ll typically have episodes of intense pain separated by periods of little or no discomfort, sometimes hours or even days apart. Each episode often means the stone has shifted position. Between episodes, you might feel perfectly fine, which can be confusing if you’re expecting continuous symptoms.
What Makes It Feel Better or Worse
Drinking plenty of water helps move the stone along and can reduce the duration of the process. Staying hydrated keeps urine flowing, which creates pressure behind the stone and helps push it through. Most people are advised to drink enough to produce clear or light yellow urine throughout the day.
Heat on the affected side, like a heating pad on your flank or lower abdomen, can ease the muscle spasms that contribute to the wave-like pain. Over-the-counter pain relief can take the edge off milder episodes. Movement sometimes helps too. Walking or light activity may encourage the stone to shift, though during a severe wave of pain, most people find it difficult to do anything but wait it out. Lying still doesn’t speed up passage, but it may be all you can manage in the moment.