Ursodiol (ursodeoxycholic acid, UDCA) is a naturally occurring bile acid found in small quantities in normal human bile and in larger quantities in the biles of certain species of bears. Ursodiol is used to dissolve gallstones in patients who do not need to have their gallbladders removed or in those in whom surgery should be avoided because of other medical problems. What is ursodiol? Ursodiol capsules are used to dissolve small gallstones that cannot be removed with surgery, or to prevent gallstones that may occur during rapid weight loss. Ursodiol (Actigall) is a bile acid that prevents and helps dissolve certain gallstones. It works to lower the cholesterol content of bile and bile stones by reducing the production and secretion of cholesterol from the liver and the reabsorption of cholesterol by the intestines. Ursodiol is a type of bile acid that your body naturally forms in small amounts. When you take ursodiol as a medicine, it changes your bile so that cholesterol (a main component of gallstones). What is this medication? URSODIOL (ER soe dye ol) prevents and treats gallstones. It works by stopping your liver from making cholesterol, a substance that causes some types of gallstones to form. It also breaks down the cholesterol that makes up the gallstone. Ursodeoxycholic acid (UDCA), also known as ursodiol, is a secondary bile acid, produced in humans and most other species from metabolism by intestinal bacteria.