Gallstones are hard, pebble-like pieces of material, usually made of cholesterol or bilirubin, that develop in your gallbladder. When gallstones block your bile ducts, they can cause sudden pain, which means you need medical attention right away. If left untreated, they can cause complications.

Being overweight or having obesity may make you more likely to develop gallstones. Losing weight very quickly also may raise your chances of forming gallstones.

When gallstones block your bile ducts, bile builds up in your gallbladder, causing a gallbladder attack. Gallbladder attacks usually cause pain in the upper right abdomen; gallstones may form if bile contains too much cholesterol, too much bilirubin, or not enough bile salts.

If you are having a gallbladder attack or other symptoms, you need to have your gallstones treated right away, most likely with surgery to remove the gallbladder. Nonsurgical treatments are rarely used. Learn more about ways to prevent gallstones.

Health care professionals use your medical history, a physical exam, and lab and imaging tests to diagnose and find gallstones. Blood tests can show signs of infection or inflammation of the bile ducts, gallbladder, pancreas, or liver.

You can lower your risk of gallstones by maintaining a healthy weight through proper diet and nutrition. Talk with your health care professional before you make any changes to your eating plan.

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