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Anticoagulants/Cholestyramine; Colesevelam

This information is generalized and not intended as specific medical advice. Consult your healthcare professional before taking or discontinuing any drug or commencing any course of treatment.

Medical warning:

Moderate. These medicines may cause some risk when taken together. Contact your healthcare professional (e.g. doctor or pharmacist) for more information.

How the interaction occurs:

When these two medicines are taken together, your cholesterol medicine may cause your body to not absorb the blood-thinner.

What might happen:

The effects of the blood-thinner may decrease and you may be at risk of developing blood clots.There is an increased chance of bleeding if you are taking these medicines together and you stop taking your cholesterol medicine. You may experience bleeding from your gums, nose bleeds, unusual bruising, or dark stools.

What you should do about this interaction:

Contact your healthcare professionals (e.g. doctor or pharmacist) as soon as possible about taking these two medicines together. Your doctor or pharmacist may instruct you to separate the times you take these medicines. If your doctor prescribes these medicines together, you may need to check your bleeding times more often.Your healthcare professionals may already be aware of this interaction and may be monitoring you for it. Do not start, stop, or change the dosage of any medicine before checking with them first.


1.Meinertz T, Gilfrich HJ, Groth U, Jonen HG, Jahnchen E. Interruption of the enterohepatic circulation of phenprocoumon by cholestyramine. Clin Pharmacol Ther 1977 Jun;21(6):731-5.

2.Robinson DS, Benjamin DM, McCormack JJ. Interaction of warfarin and nonsystemic gastrointestinal drugs. Clin Pharmacol Ther 1971 May-Jun; 12(3):491-5.

3.Gallo DG, Bailey KR, Sheffner AL. The interaction between cholestyramine and drugs. Proc Soc Exp Biol Med 1965 Oct;120(1):60-5.

4.Keuntzel WP, Brunk SF. Cholestyramine-warfarin interaction in man. Clin Res 1970;18(3):594.

5.Hahn KJ, Eiden W, Schettle M, Hahn M, Walter E, Weber E. Effect of cholestyramine on the gastrointestinal absorption of phenprocoumon and acetylosalicylic acid in man. Eur J Clin Pharmacol 1972 Jun;4(3):142-5.

6.Harvengt C, Desager JP. Effect of colestipol, a new bile acid sequestrant, on the absorption of phenprocoumon in man. Eur J Clin Pharmacol 1973 Jun; 6(1):19-21.

7.Meinertz T, Gilfrich MJ, Bork R, Jahnchen E. Treatment of phenprocoumon intoxication with cholestyramine. Br Med J 1977 Aug 13;2(6084):439.

8.Hunninghake DB, Pollack E. Effect of bile acid sequestering agents on the absorption of aspirin, tolbutamine, and warfarin. Fed Proc 1977;36(3):996.

9.Jahnchen E, Meinertz T, Gilfrich HJ, Kersting F, Groth U. Enhanced elimination of warfarin during treatment with cholestyramine. Br J Clin Pharmacol 1978 May;5(5):437-40.

10.Welchol (colesevelam hydrochloride) US prescribing information. Daiichi Sankyo, Inc. June, 2013.

Selected from data included with permission and copyrighted by First Databank, Inc. This copyrighted material has been downloaded from a licensed data provider and is not for distribution, expect as may be authorized by the applicable terms of use.

CONDITIONS OF USE: The information in this database is intended to supplement, not substitute for, the expertise and judgment of healthcare professionals. The information is not intended to cover all possible uses, directions, precautions, drug interactions or adverse effects, nor should it be construed to indicate that use of a particular drug is safe, appropriate or effective for you or anyone else. A healthcare professional should be consulted before taking any drug, changing any diet or commencing or discontinuing any course of treatment.

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