A kidney stone typically feels like an intense, cramping pain in your side or lower back that comes in waves lasting 20 to 60 minutes each. Most people describe it as one of the worst pains they’ve ever experienced. The pain often starts suddenly, peaks within one to two hours, and can shift to different parts of your body as the stone moves through your urinary tract. But pain is only part of the picture. Kidney stones also bring nausea, urinary changes, and a restless inability to get comfortable.
Where the Pain Starts
The first thing most people notice is a deep, gripping pain in the flank, the area on either side of your lower back just below your rib cage. This happens when a stone moves out of the kidney and enters the ureter, the narrow tube connecting your kidney to your bladder. The stone partially blocks urine flow, causing urine to back up and stretch the kidney and ureter. Both structures are covered in pain-sensing nerves that respond to that stretching force, which is what produces the severe, sometimes overwhelming pain.
At this stage the pain can feel dull and constant, or it can hit in sharp, intense waves. Many people try shifting positions, pacing, or curling up, but nothing really helps. Unlike muscle pain or a backache, kidney stone pain doesn’t respond to movement or rest. It simply persists until the stone shifts or the ureter relaxes.
How the Pain Moves
One of the most distinctive features of a kidney stone is that the pain migrates. As the stone travels down the ureter, the location of your pain follows it. This pattern often provides clues about exactly where the stone is sitting.
- Upper ureter: Pain stays in the flank and lower back, often radiating toward the side of your abdomen.
- Mid-ureter: Pain shifts toward the lower abdomen, sometimes mimicking appendicitis or a pulled muscle.
- Lower ureter, near the bladder: Pain radiates into the groin or pelvic area. In men, this can include sharp pain in the testicles. In women, it may be felt deep in the pelvis or in the labia.
This traveling pain is a hallmark of kidney stones. If you feel a pain that started in your back and has gradually crept toward your groin over hours or days, that pattern alone is a strong signal that a stone is working its way down.
The Wave Pattern
Kidney stone pain rarely stays at a constant level. Instead, it comes in waves called renal colic. Each wave can last anywhere from 20 to 60 minutes, sometimes longer in severe cases. During a wave, the pain can be excruciating. Between waves, it may drop to a dull ache or disappear entirely, giving you a brief window of relief before the next round hits.
This wave pattern happens because the ureter is a muscular tube that contracts rhythmically, trying to push the stone along. Each contraction squeezes around the stone, temporarily worsening the blockage and stretching the tissue. When the muscle relaxes, pressure eases and the pain fades. Some people have a few waves over a single evening; others deal with repeated episodes over days or weeks.
Nausea, Vomiting, and Other Symptoms
The pain alone is enough to cause nausea, and many people vomit during an acute episode. This isn’t a coincidence. The kidneys and the gut share nerve pathways, so intense kidney pain triggers a gastrointestinal response. Some people feel nauseous even before the pain becomes severe, which can be confusing if you initially mistake the episode for a stomach bug.
Other common symptoms include:
- Blood in urine: Your urine may look pink, red, or dark brown (sometimes described as cola-colored). The stone scrapes the lining of the ureter as it moves, causing small amounts of bleeding. This isn’t always visible to the naked eye, but when it is, it can be alarming.
- Frequent urination: You may feel a persistent, urgent need to urinate, especially as the stone reaches the lower ureter near the bladder.
- Burning during urination: Pain or a burning sensation when you pee is common, particularly once the stone is close to or inside the bladder.
- Restlessness: Unlike many painful conditions where lying still helps, people with kidney stones often can’t find a comfortable position. Pacing, shifting, and fidgeting are typical.
Small Stones vs. Large Stones
Not every kidney stone produces the same experience. Size matters enormously. Stones smaller than 4 millimeters (roughly the width of a pea) pass on their own about 80 percent of the time, often within one to two weeks. The pain may be moderate and manageable with over-the-counter pain relief and plenty of water.
Stones between 4 and 6 millimeters are more unpredictable. Around 60 percent still pass naturally, but the process takes longer and the pain tends to be more intense. Stones larger than 6 millimeters usually need medical treatment, since only about 20 percent pass on their own. These larger stones can cause prolonged blockages and sustained, severe pain.
Once a stone reaches the bladder, the worst is typically over. The urethra (the tube from the bladder to the outside) is wider than the ureter, so the final stage of passing a stone usually takes just a few days and causes far less pain. You might feel a brief pinch or pressure when the stone finally exits, or you might not notice it at all.
What Some People Confuse It With
Because kidney stone pain can show up in so many locations, it often gets mistaken for other problems at first. Lower back pain leads people to think they pulled a muscle. Pain in the lower right abdomen mimics appendicitis. Groin or testicular pain in men can raise concerns about a hernia or torsion. Pelvic pain in women sometimes gets confused with ovarian cysts or menstrual cramps.
The key differences are the wave pattern, the migrating location, and the combination of flank pain with urinary changes. A pulled muscle doesn’t make your urine pink. Appendicitis doesn’t come and go in 30-minute waves. If you’re experiencing pain that shifts from your back toward your groin, especially alongside blood in your urine or nausea, a kidney stone is high on the list of likely causes.
Warning Signs That Need Urgent Attention
Most kidney stones, while painful, pass without lasting harm. But certain symptoms signal a complication that needs prompt medical care. A fever alongside kidney stone pain can indicate an infection trapped behind the blockage, which can become serious quickly. The combination of a high temperature, chills, and flank pain is a situation that warrants an emergency visit.
Other red flags include a complete inability to urinate, pain so severe that you’re vomiting repeatedly and can’t keep fluids down, or symptoms that persist beyond four to six weeks without the stone passing. A stone that stays lodged in the ureter for too long can damage the kidney, so prolonged episodes need medical follow-up even if the pain becomes tolerable.