Gallstones are hardened deposits that form inside your gallbladder, a small organ tucked beneath your liver that stores bile. They range from as small as a grain of sand to as large as a golf ball, and roughly three out of four are made mostly of cholesterol. Many people have gallstones without ever knowing it, but when a stone blocks one of the bile ducts, the pain can be intense and sudden.
How Gallstones Form
Your liver produces bile, a digestive fluid that helps break down fats. Bile flows into the gallbladder, where it’s stored and concentrated between meals. Gallstones develop when the chemical balance of that bile tips out of proportion. If your liver puts out more cholesterol than the bile can keep dissolved, the excess cholesterol begins to crystallize. These tiny crystals get trapped in the mucus lining the gallbladder wall, forming a thick sludge. Over time, the crystals clump together and harden into stones.
A second, less common pathway involves bilirubin, a waste product your body creates when it breaks down old red blood cells. Conditions that cause your body to destroy red blood cells faster than normal, like certain blood disorders or liver disease, flood the bile with excess bilirubin. That bilirubin solidifies into dark brown or black pigment stones. Unlike cholesterol stones, pigment stones can’t be dissolved with medication.
A gallbladder that doesn’t contract and empty regularly also raises the risk. When bile sits too long, it becomes more concentrated, giving crystals more time and material to grow.
Who Gets Gallstones
Gallstones become more common with age. Claims data from 2019 show that among commercially insured adults under 25, only about 0.12% had a gallstone diagnosis. By ages 65 to 74, that figure climbed to roughly 1%, and among Medicare beneficiaries over 85, nearly 3% carried a diagnosis. Women are affected more often than men during their reproductive years, likely because estrogen increases cholesterol secretion into bile. After age 65, the gap between men and women narrows considerably.
Several lifestyle and metabolic factors raise your odds:
- Excess weight. Obesity increases cholesterol output from the liver, feeding stone formation.
- Rapid weight loss. Losing weight too quickly shifts the cholesterol balance in bile dramatically. If you’re trying to lose weight, aiming for 1 to 2 pounds per week is safer for your gallbladder than crash dieting.
- High-fat, low-fiber diets. Both contribute to cholesterol supersaturation in bile.
- Skipping meals or fasting. When you don’t eat, the gallbladder doesn’t contract and empty, letting bile stagnate.
- Diabetes. People with diabetes tend to have higher triglyceride levels, which promotes stone growth.
- Sedentary lifestyle. Physical inactivity independently raises risk, even after accounting for body weight.
What a Gallstone Attack Feels Like
Most gallstones are “silent,” meaning they sit in the gallbladder without causing symptoms. The trouble starts when a stone shifts and blocks one of the ducts that carry bile. This triggers what’s called biliary colic: a sudden, rapidly intensifying pain in the upper right side of your abdomen, or sometimes right below the breastbone in the center. The pain often radiates to your back between the shoulder blades or into your right shoulder. It typically hits after a meal, especially a fatty one, because eating signals the gallbladder to squeeze and release bile.
An attack usually lasts anywhere from several minutes to a few hours. The pain tends to be steady and deep rather than crampy, and it can be severe enough to send people to the emergency room. Nausea and vomiting often come along with it. Once the stone dislodges or passes through the duct, the pain fades. But if you’ve had one attack, more are likely to follow.
When Gallstones Become Dangerous
A stone that stays lodged in a duct can cause complications that go well beyond a painful episode. If bile backs up behind the blockage, the gallbladder can become inflamed and infected, a condition called cholecystitis. Signs that a simple attack has turned into something more serious include pain that lasts longer than a few hours without letting up, fever, chills, or a yellowing of the skin and eyes (jaundice). Jaundice signals that a stone has blocked the common bile duct, which can also trigger inflammation of the pancreas. Gallstone pancreatitis causes severe upper abdominal pain that radiates to the back and usually requires hospitalization.
How Gallstones Are Diagnosed
An abdominal ultrasound is the standard first test. It’s quick, painless, and doesn’t involve radiation. When gallstones are actually present, ultrasound catches them with perfect specificity, meaning it essentially never mistakes something else for a stone. Its sensitivity is somewhat lower, around 68% for detecting acute gallbladder inflammation, so a CT scan (which has roughly 85% sensitivity for inflammation) is sometimes used as a follow-up when ultrasound results are inconclusive but suspicion remains high.
Treatment Options
Silent gallstones that have never caused symptoms generally don’t need treatment. Once you start having attacks, though, the recommended treatment for most people is surgical removal of the gallbladder. The procedure is done laparoscopically through a few small incisions. Most people go home the same day or the next morning. You can typically return to desk work within a week and resume normal activities within two weeks, though full recovery of your energy level takes up to six weeks.
Living without a gallbladder is straightforward. Bile still flows from the liver directly into the small intestine; you just lose the storage reservoir. Some people notice looser stools for a few weeks after surgery, but this usually resolves on its own.
Dissolving Stones Without Surgery
For people who can’t have surgery or prefer to avoid it, an oral medication that works by thinning the bile can sometimes dissolve cholesterol stones. In one study of patients who took the medication for at least 12 months, about 57% saw their stones completely disappear, compared to virtually none in the group that didn’t take it. Stones smaller than 5 millimeters responded best. The treatment only works on cholesterol stones, not pigment stones, and it requires at least six months of daily use. Even when it works, stones often come back once the medication is stopped, which is why surgery remains the more definitive solution.
Reducing Your Risk
Diet and lifestyle choices have a real impact on gallstone formation. A diet higher in fiber and lower in refined carbohydrates and saturated fat helps keep cholesterol levels in bile manageable. Eating regular meals matters too, since skipping meals leaves the gallbladder sitting full and stagnant.
Coffee appears to be genuinely protective. A large Harvard study tracking roughly 46,000 men found that those who drank four or more cups of caffeinated coffee per day had a 45% lower risk of developing gallstones compared to non-drinkers. Even two to three cups a day was linked to a modest reduction. The benefit seems specific to caffeinated coffee: decaf, tea, and soda didn’t show the same effect. Caffeine stimulates gallbladder contractions and lowers cholesterol concentration in bile, both of which work against stone formation.
If you need to lose weight, the pace matters as much as the amount. Gradual weight loss of 1 to 2 pounds per week keeps bile chemistry stable. Very rapid weight loss, whether from crash diets or weight-loss surgery, is one of the strongest triggers for new gallstone formation, which is why doctors often prescribe preventive medication for patients after bariatric procedures.