What Are Bile Acid Sequestrants and How Do They Work?

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If your cholesterol is high, your healthcare provider may decide to add a bile acid sequestrant to your cholesterol-lowering regimen. Bile acid sequestrants, also known as bile acid resins or BARs, are a class of medications used to help lower your cholesterol levels. Currently, three medications in this drug class are available in the United States:

    Welchol (colesevelam) is available as a tablet or resin powder. Colestid (colestipol) and Questran (cholestyramine) are available only as resin powders.

    How Do Bile Acid Sequestrants Lower Your Cholesterol?

    These drugs work by binding to bile acids and preventing the absorption of bile acids from the small intestine. Instead of being absorbed into the blood, the combination of bile acids and the drug is excreted in the feces. In response to lowered bile acids in the body, your liver will convert cholesterol into more bile acids. Additionally, LDL receptors will also be increased in the liver. These actions help lower cholesterol levels in the blood.

    As a result, bile acid sequestrants mainly lower LDL cholesterol between 15% to 30% and only slightly raise HDL cholesterol by about 3% to 5%.

    These drugs do not appear to affect triglyceride levels but, in some cases, bile acid sequestrants may actually raise your triglycerides if taken for a long period of time.

    Because they have not been proven to lower the risk of a heart attack or stroke, bile acid sequestrants are not as commonly prescribed as other cholesterol-lowering medications, especially statins. However, they can be taken alone or combined with other cholesterol-lowering medications to help you manage your lipid levels.

    Common Side Effects of Bile Acid Sequestrants

    Side effects from taking bile acid sequestrants mostly consist of gastrointestinal problems, including:

    • Nausea
    • Constipation
    • Bloating
    • Flatulence

    The side effects can be managed by increasing your fluid intake, taking a stool softener or by adding fiber to your diet.

    Some people may find it difficult to consistently take their bile acid sequestrant. For instance, some individuals might find the resins to be too gritty to taste - especially if they have to take them more than one time a day. Although there are ways to improve the taste of the resins, some taking the drug still cannot tolerate their taste. Additionally, the Welchol tablet is large and may be difficult to swallow for some people. If you have been prescribed a bile acid sequestrant and are having difficulty taking your medication, you should let your healthcare provider know of this.

    Who Should Not Take a Bile Acid Sequestrant?

    Other than disclosing your complete medical history, you should also notify your healthcare provider if you have any of these other medical conditions below:

    • If you already have very high triglyceride levels or have ever experienced medical issues due to very high triglycerides, such as pancreatitis. This is due to the fact that bile acid sequestrants may raise your triglyceride levels further.
    • Bile acid sequestrants may interact with some vitamins or other medications that you are taking. Therefore, you should notify all of your healthcare providers if you are taking a bile acid sequestrant so that they can make sure that the drug is not interacting with any other medications, vitamins, or supplements that you are taking. In some cases, your healthcare provider may request that you increase the amount of time between taking your bile acid sequestrant and other medications.
    • Bile acid sequestrants have not been studied in women who are breastfeeding or pregnant. Although bile acid sequestrants do not appear to cross into the bloodstream, they can limit the absorption of certain important vitamins.
    • If you have gastrointestinal conditions, such as hemorrhoids or constipation, taking bile acid sequestrants may worsen these conditions. Additionally, you should let your healthcare provider know if you have ever had a bowel obstruction.

    Your healthcare provider will weigh the benefits and risks of prescribing a bile acid sequestrant for you in these instances to help you manage your lipids.


    Dipiro JT, Talbert RL. Pharmacotherapy: A Pathophysiological Approach, 9th ed 2014.

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