The first sign of a kidney stone is usually a sudden, intense pain in your side or lower back, just below the ribs. This pain often arrives without warning and can be one of the most severe sensations people experience. But pain isn’t always the very first clue. Some people notice changes in their urine, like a pink or brownish tint, before the sharper symptoms kick in.
Where the Pain Starts and How It Moves
A kidney stone that’s still sitting in the kidney often causes no symptoms at all. The trouble begins when it moves into one of the ureters, the narrow tubes connecting each kidney to the bladder. Once a stone enters that tight space, it can block urine flow, cause the kidney to swell, and trigger spasms in the ureter wall. That’s when the pain hits.
The classic pain, called renal colic, is an intense ache between your lower ribs and hip on the affected side. From there, it can radiate to your back, lower abdomen, or groin. Some people describe it as a constant, deep pressure, while others feel sharp stabs that come and go in waves lasting 20 to 60 minutes each. The pain typically peaks about one to two hours after it begins, then fades before the next wave rolls in. In severe cases, these cycles can stretch even longer.
One detail that catches people off guard: the pain can shift location as the stone travels. A stone near the kidney tends to produce side and back pain, while one closer to the bladder may cause discomfort lower in the abdomen or groin. In men, pain sometimes radiates into the testicles. In women, it can be felt near the labia or confused with menstrual cramps or ovarian pain. This shifting quality is actually a useful signal, because it means the stone is moving, which is generally what you want.
Changes in Your Urine
Blood in the urine is one of the earliest and most common signs. Sometimes it’s visible, turning urine pink, red, or brown. Other times the amount of blood is so small it only shows up on a lab test. Either way, a stone scraping along the lining of the ureter is usually the cause.
You may also notice that you need to urinate more often than usual, or feel a persistent urgency even when your bladder isn’t full. Some people experience a burning sensation while urinating, which can easily be mistaken for a urinary tract infection. In fact, kidney stones and UTIs can occur together, since a stone that partially blocks urine flow creates conditions where bacteria thrive. If you have both burning urination and flank pain, that overlap is worth paying attention to.
Urine that looks cloudy or has an unusual smell can be another early signal, particularly if an infection has developed alongside the stone.
Nausea and Vomiting
Kidney stones don’t just affect the urinary tract. The kidneys and the digestive organs share nerve pathways, so when a stone causes intense pain or swelling in the kidney, your gut often reacts too. Nausea and vomiting are extremely common during a stone episode, and for some people these symptoms are just as disruptive as the pain itself. If you’re experiencing waves of flank pain paired with an unsettled stomach, that combination is a strong indicator of a stone rather than a purely digestive issue.
Subtle Early Clues People Miss
Not every kidney stone announces itself with dramatic pain. Smaller stones can produce vague, easy-to-dismiss symptoms for days or even weeks before anything escalates. A mild, persistent ache on one side of your lower back that doesn’t seem related to movement or posture is one example. Another is a general sense of restlessness or inability to get comfortable, especially at night. People sometimes describe feeling like something is “off” in their abdomen without being able to pinpoint exactly what.
Frequent urination without an obvious reason, or urine that looks slightly darker than usual, can also precede the more intense phase. These signs are easy to chalk up to dehydration or a mild infection, which is why many stones go unrecognized until they cause a full-blown episode of renal colic.
Signs That Signal an Emergency
Most kidney stones, while painful, resolve without permanent harm. But certain symptoms indicate a more serious situation. Fever and chills alongside stone symptoms suggest an infection has developed in the blocked kidney. This is a genuine emergency because an infected, obstructed kidney can become life-threatening quickly. Similarly, if you’re unable to urinate at all, or if the pain is so severe that you can’t sit still, lie down, or keep fluids down, that warrants immediate medical attention.
Blood in the urine on its own is not necessarily an emergency, but heavy or persistent bleeding, particularly combined with dizziness or lightheadedness, should be evaluated promptly.
How Kidney Stones Are Confirmed
If your symptoms point toward a stone, the standard way to confirm it is a CT scan done without contrast dye. This is considered the gold-standard imaging test for adults because it can detect stones of nearly any size and composition, and it shows exactly where the stone is located. For pregnant women, ultrasound is used instead to avoid radiation exposure, and ultrasound is also preferred for children for the same reason.
A urine test will check for blood and signs of infection, and blood work can reveal whether the stone is affecting kidney function. Once a stone is confirmed, its size determines what happens next. Stones smaller than about 5 to 6 millimeters (roughly the width of a pencil eraser) have a reasonable chance of passing on their own with fluids and pain management. Larger stones are more likely to need medical intervention to break them up or remove them.
What to Watch For Going Forward
About half of people who have one kidney stone will develop another within five to ten years. Knowing what the first signs feel like gives you an advantage the second time around. If you start noticing that familiar one-sided back pain, changes in urine color, or unexplained nausea, you can act faster and get evaluated before the pain peaks. Staying well hydrated is the single most effective way to reduce recurrence, since dilute urine makes it harder for the minerals that form stones to crystallize in the first place.