Kidney stones and gallstones form in completely different organs, are made of different materials, cause pain in different parts of your body, and are treated in different ways. The word “stone” is where the similarities mostly end. Kidney stones are hard mineral deposits that form inside your kidneys, while gallstones are hardened clumps of cholesterol or bile pigment that form in your gallbladder. Understanding which is which matters because the pain they cause can sometimes feel confusingly similar.
Where They Form
Kidney stones develop in your kidneys, the two fist-sized organs in your lower back that filter waste from your blood and produce urine. When certain minerals in your urine become too concentrated, they crystallize and clump together into a stone. The stone may stay in the kidney or travel down the ureter, the narrow tube connecting each kidney to your bladder.
Gallstones form in your gallbladder, a small pear-shaped sac tucked under your liver on the right side of your upper abdomen. The gallbladder stores bile, a digestive fluid your liver produces to help break down fats. When the chemical balance of that bile tips too far in one direction, solid particles crystallize and grow into stones. These can range from the size of a grain of sand to the size of a golf ball.
What They’re Made Of
The chemical makeup of each stone type is entirely different, which reflects the different fluids they form in.
About 70% of kidney stones are calcium oxalate, a mineral salt that crystallizes when oxalate (found in many plant foods) binds with calcium in urine. The remaining 30% are split among calcium phosphate stones (5 to 10%), uric acid stones (about 10%), struvite stones caused by urinary infections (15 to 20%), and a rare type called cystine stones (around 1%).
Gallstones are a cholesterol story. The most common type is made primarily of hardened cholesterol. Pigment gallstones, the second type, are brown or black and composed mainly of calcium salts of bilirubin, a waste product from the breakdown of red blood cells. Mixed gallstones contain varying proportions of both cholesterol and bilirubin salts. In short, kidney stones are mineral-based and gallstones are fat- or pigment-based.
How the Pain Differs
Both stones can produce intense pain, but the location is the clearest way to tell them apart. Kidney stone pain typically hits as a sharp, cramping sensation in your lower back or side, often radiating down toward your lower abdomen and groin. Many people initially mistake it for a back problem. The pain tends to come in waves as the stone moves through the ureter, and it can shift location as the stone travels.
Gallstone pain centers in your mid-upper abdomen or right upper abdomen, and it often radiates to your back or under your right shoulder blade. This pain, sometimes called a gallbladder “attack,” usually starts after a meal, particularly a fatty one, because eating triggers your gallbladder to squeeze out bile. It tends to build to a steady, pressing ache rather than the sharp waves typical of kidney stones. Episodes can last anywhere from 30 minutes to several hours.
Both types of stone can also cause nausea and vomiting. Kidney stones frequently cause blood in the urine, while gallstones are more likely to cause bloating, indigestion, and in some cases yellowing of the skin if a stone blocks a bile duct.
Who Gets Them
Kidney stones affect roughly 10.6% of men and 7.1% of women in the United States, making them slightly more common in men. Dehydration is one of the biggest risk factors, along with diets high in sodium, animal protein, or oxalate-rich foods. Obesity, high blood pressure, diabetes, and gout all raise kidney stone risk.
Gallstones are more common in women, partly because of the effects of estrogen on cholesterol levels in bile. Pregnancy, hormonal birth control, and hormone replacement therapy all increase gallstone risk. Obesity and rapid weight loss are strong risk factors, as are older age and a family history of gallstones. Diabetes, high blood pressure, and insulin resistance are shared risk factors for both conditions.
In fact, a large study following tens of thousands of men and women found that people with a history of gallstones were roughly 60 to 85% more likely to also have had kidney stones. The connection likely comes down to shared metabolic risk factors like obesity and insulin resistance rather than one stone type directly causing the other.
How They’re Diagnosed
Ultrasound is typically the first imaging test for both conditions. Gallbladder stones show up clearly on ultrasound as bright spots that cast a shadow behind them, and ultrasound remains the go-to tool for confirming suspected gallstones because of its high sensitivity and lack of radiation.
Kidney stones also appear on ultrasound, but a CT scan without contrast dye is generally considered the gold standard for kidney stones. CT can detect nearly all stone types regardless of size or composition and precisely maps where the stone sits in the urinary tract, which helps determine whether it’s likely to pass on its own.
Treatment: Passing vs. Removing
This is one of the biggest practical differences between the two. Small kidney stones, generally those under 5 to 6 millimeters, often pass on their own through your urine. The process can be painful, and your doctor may recommend pain relievers and increased fluid intake to help things along. Larger kidney stones that won’t pass may need to be broken up with sound waves (a procedure done from outside the body) or removed through a small scope inserted through the urinary tract.
Gallstones follow a different path entirely. Many gallstones never cause symptoms and never need treatment. But once they start causing repeated painful attacks, the standard treatment is surgical removal of the entire gallbladder. This is one of the most common surgeries performed, typically done through a few small incisions. You don’t need your gallbladder to live. Once it’s removed, bile flows directly from your liver into your small intestine. Some people experience temporary diarrhea afterward, but digestion generally returns to normal.
Oral medications that dissolve gallstones do exist, but they can take months or years to work, and stones tend to come back once you stop taking them. These are reserved for people who can’t undergo surgery. There’s no equivalent for kidney stones: you either pass them, break them up, or have them physically removed.
Complications if Left Untreated
A kidney stone stuck in the ureter can block urine flow, leading to a backup of pressure in the kidney. If that blockage persists, it can cause kidney infection or, in severe cases, permanent kidney damage. An infected, obstructed kidney is a medical emergency requiring urgent drainage.
Untreated gallstones carry their own serious risks. A stone lodged in the bile duct can cause severe inflammation or infection of the gallbladder, damage to the bile ducts or liver, and gallstone pancreatitis, a painful and potentially dangerous inflammation of the pancreas. The NIDDK notes that many people don’t experience gallstone symptoms until a complication has already developed, and untreated gallstone complications can be life-threatening.
Preventing Each Type
Because the two stones have different chemical origins, prevention strategies differ. For kidney stones, the single most effective step is drinking enough water to produce at least 2 to 2.5 liters of urine per day. Reducing sodium intake helps because excess sodium forces more calcium into your urine. Moderating animal protein and being mindful of high-oxalate foods (spinach, rhubarb, nuts, chocolate) can also lower risk if you’re prone to calcium oxalate stones.
Gallstone prevention centers more on maintaining a healthy weight and avoiding crash diets or very rapid weight loss, which can shift bile chemistry toward stone formation. A diet lower in refined carbohydrates and saturated fat, with adequate fiber, supports healthier bile composition. Regular physical activity independently lowers gallstone risk. Unlike kidney stones, where hydration is the cornerstone of prevention, drinking extra water doesn’t prevent gallstones.