Gallstones are lumps of solid material that form in your gallbladder. They are made when the digestive juice called bile gets hard and stone-like.

The gallbladder is a small organ under your liver. It stores bile made by the liver. Bile is made of several things such as cholesterol, bile salts, and a yellowish pigment (bilirubin).

Gallstones can be as small as a grain of sand or as big as a golf ball. Your gallbladder may form a single large stone, hundreds of tiny stones, or both sizes at the same time. In some cases, gallstones block the tubes that carry bile (bile ducts). This can lead to a life-threatening infections of the bile ducts, pancreas, or liver.

Once you have had gallstones, you are at risk of having more.

There are 2 types of gallstones: cholesterol and pigment.

Cholesterol stones

  • Are the most common in the U.S.
  • Are most often a yellow-green color
  • Are made mainly of hardened cholesterol

Pigment stones

  • Are less common
  • Are a dark color
  • Are made of a yellowish pigment called bilirubin

Key Factors

Some people have a higher risk for gallstones. These include:

  • Native Americans. They have the highest rates of gallstones in the U.S. This may be genetic as they have very high levels of cholesterol in their bile.
  • Mexican Americans. They have higher than average rates of gallstones.
  • Women. They are twice as likely to have gallstones as men.
  • People over 60.
  • People with a family history of gallstones. Gallstones seem to run in some families (inherited). There may be a genetic link.

Health issues that may raise your risk for gallstones include:

  • Obesity. This is a major risk factor, mainly for women.
  • Estrogen. Women may have extra estrogen from pregnancy, hormone replacement therapy, or birth control pills. This seems to raise cholesterol levels in bile and slow down gallbladder movement. Both can lead to gallstones.
  • Diet. Eating a high-fat, high-cholesterol, or low-fiber diet raises your risk. They lead to more cholesterol in the bile and reduced gallbladder emptying.
  • Cholesterol-lowering medicines. These medicines can increase the amount of cholesterol in bile.
  • Diabetes. People with diabetes often have high levels of fatty acids (triglycerides). This raises the risk for gallstones.
  • Very fast weight loss. As the body processes fat during very fast weight loss, the liver sends out extra cholesterol into bile.
  • Not eating for a few days (prolonged fasting). Fasting slows down gallbladder movement. Over time, your bile has too much cholesterol.