Bile acid resins are a type of cholesterol-reducing drug. These medications lower the levels of fats (lipids) in the blood, including cholesterol and triglycerides. Some bile acid resins have been shown to reduce the level of LDL (“bad”) cholesterol between 10 and 20 percent, while simultaneously raising the level of HDL (“good”) cholesterol.

Bile acid resins may be prescribed in conjunction with other cholesterol-reducing medications, including statins, fibrates and nicotinic acid. All are commonly used to treat high cholesterol (hypercholesterolemia). When prescribed with other medications, bile acid resins have been shown to reduce LDL levels by as much as 50 percent. 

Bile acids work by altering the chemistry of cholesterol processing. Under normal circumstances, the liver takes cholesterol out of the blood to make bile, which is used in the in the intestines during the digestive process. Most bile is later returned to the liver and reused. Bile acid resins block the recycling of bile acids. To replace the lost bile acids, the liver is forced to remove more cholesterol from the blood to manufacture more bile. Bile acid resins are usually taken in powder form or in a chewable bar.

The most common bile acid resins are cholestyramine (brand names Questron and Questron Light) and colestipol (brand name Colestid). The cholesterol-lowering drug colesevelam (brand name WelChol) is often grouped with bile acid resins because it lowers cholesterol and triglyceride levels in a manner similar to bile acid resins.

Some bile acid resins are also used to lessen symptoms of patients with liver disease. Liver disease can cause a build-up of bile acids, resulting in symptoms such as severe itching or diarrhea, which may be treated with a bile acid resin (colestipol). In addition, cholestyramine and colestipol may be used to treat an overdose of the inotropic medication digitalis or for patients with too much of a substance called oxalate in their urine.

All types of cholesterol-lowering drugs are effective to some degree. However, statins are normally considered the first line of defense. Bile acid resins are not absorbed by the body, unlike statin and fibrates. They may be a more viable option for patients for whom other cholesterol-reducing medications are not recommended (e.g., pregnant women).