A gallstone is a hard, rock-like deposit which forms in the gallbladder. A number of factors including excess body weight, low levels of physical activity, and high-fat, low-fiber diets are believed to be contributing factors. People over the age of 40 are also at increased risk for gallstones. Symptoms include sudden, intense abdomen pain, nausea and vomiting, or referred pain in the shoulders. Treatment options include surgical removal, or dissolution of the gallstones with the ingestion of orally taken acidic medications. Smaller stones may be induced to pass through the bile duct into the small intestine, where they can then be excreted through bowel movements.