[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Pharmacology](https://durgical.com/en/pharmacology/) › [Bile acid sequestrants](https://durgical.com/en/pharmacology/classes/bile-acid-sequestrants/) › Colestyramine [Pharmacology](https://durgical.com/en/pharmacology/) · [Bile acid sequestrants](https://durgical.com/en/pharmacology/classes/bile-acid-sequestrants/) # Colestyramine A resin powder that binds bile acids in the gut. It lowers LDL cholesterol and relieves itching caused by partial bile duct obstruction. Updated 2026-11-01 - Class: [Bile acid sequestrants](https://durgical.com/en/pharmacology/classes/bile-acid-sequestrants/) - Target: Bile acids in the gut lumen - ATC code: C10AC01 Also called: cholestyramine ## Mechanism of action Colestyramine is a chloride-form anion-exchange resin. In the intestine it swaps chloride for bile acids and holds them, so they leave in the stool instead of returning to the liver. The liver then converts more cholesterol into bile acids and increases its LDL receptors, which lowers blood LDL. Removing bile acids also eases the itch of partial biliary obstruction. - Resin swaps chloride for bile acids in the gut - Bile acids leave in the stool, not back to the liver - Liver turns cholesterol into new bile acids - More LDL receptors: blood LDL falls ## Pharmacokinetics **Absorption** Not absorbed from the digestive tract. **Elimination** In the stool, bound to bile acids. **Onset and duration** The LDL effect builds over about 1 to 2 weeks. ## Indications - Primary hypercholesterolemia (high LDL), as an adjunct to diet [Atherosclerosis and dyslipidaemia →](https://durgical.com/en/conditions/atherosclerosis-and-dyslipidaemia/) - Itching from partial biliary obstruction, for example in primary biliary cholangitis [Primary biliary cholangitis →](https://durgical.com/en/conditions/primary-biliary-cholangitis/) ## Adverse effects ### Common - Constipation (most common) - Bloating, abdominal discomfort, nausea, belching - Can raise triglycerides ### Serious (rare, important) - Fecal impaction - Bleeding from vitamin K deficiency with long use - Deficiency of vitamins A and D - Hyperchloremic acidosis, mainly in small children ## Contraindications - Complete biliary obstruction (no bile reaches the gut) - Hypersensitivity to a component ## Key interactions **Warfarin, digoxin, thyroid hormones, thiazides, propranolol, estrogens and progestins** Absorption delayed or reduced; these drugs are given at least 1 hour before or 4 to 6 hours after. **Fat-soluble vitamins (A, D, E, K) and folic acid** Reduced absorption with long use; supplements may be needed. **Ezetimibe, fenofibrate, niacin** Bound by the resin; their timing is separated. ## What is monitored - Lipid panel, including triglycerides - Bowel habits - Signs of bleeding; prothrombin time with long use - Levels or effect of narrow-margin drugs taken with it ## Administration and safety - Oral powder: always mixed with water or another fluid (or soft, moist food); never taken dry. - Not sipped slowly or held in the mouth, which can harm tooth enamel. - Other oral drugs at least 1 hour before or 4 to 6 hours after. - The «light» formulation contains phenylalanine: relevant in phenylketonuria. ## Nursing care - Before: lipid panel with triglycerides, bowel habits, the full list of oral drugs. - Encourage fluids and fiber; watch for constipation, especially in older adults. - Plan the daily timetable so other drugs are separated from the resin. - With long use, watch for bruising or bleeding (vitamin K). ## Pregnancy and breastfeeding Not absorbed, so it is not expected to reach the fetus, but it may reduce vitamin absorption; supplementation is considered. ## Memory aid «Resin = Robber»: it steals bile acids, vitamins and other drugs in the gut. Give everything else 1 hour before or 4–6 hours after. ## Test yourself Think of the answer, then tap the question to see it. ## Why does colestyramine relieve itching in partial biliary obstruction? It removes bile acids in the gut, lowering the bile acid load thought to cause the itch. ## Why is colestyramine contraindicated in complete biliary obstruction? No bile reaches the intestine, so there are no bile acids to bind and no benefit. ## Which vitamin deficiency can cause bleeding with long-term colestyramine? Vitamin K deficiency, causing low prothrombin. [Add to my cards (3)](https://durgical.app/estudiar/?add=/en/pharmacology/colestyramine/) ## Related drugs - [Colesevelam](https://durgical.com/en/pharmacology/colesevelam/) - [Ezetimibe](https://durgical.com/en/pharmacology/ezetimibe/) - [Pravastatin](https://durgical.com/en/pharmacology/pravastatin/) ## Related conditions - [Atherosclerosis and dyslipidaemia](https://durgical.com/en/conditions/atherosclerosis-and-dyslipidaemia/) - [Primary biliary cholangitis](https://durgical.com/en/conditions/primary-biliary-cholangitis/) [← Back to the class: Bile acid sequestrants](https://durgical.com/en/pharmacology/classes/bile-acid-sequestrants/) Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given. Sources: [Cholestyramine Resin: MedlinePlus Drug Information](https://medlineplus.gov/druginfo/meds/a682672.html) (MedlinePlus (U.S. National Library of Medicine), 2026); [DailyMed - CHOLESTYRAMINE powder, for suspension](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=d7c6bc5e-1916-43bf-b943-98f00f41b8de) (DailyMed (U.S. National Library of Medicine), 2026); Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed., ch. 37 (McGraw Hill, 2023); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=C10AC01) (WHO Collaborating Centre for Drug Statistics Methodology, 2026). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/pharmacology/colestyramine/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/colestyramine/