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Date of issue: May 2020
Version: 3

This is a UKTIS monograph for use by health care professionals. For case-specific advice please contact UKTIS on 0344 892 0909. To report an exposure please download and complete a pregnancy reporting form. Please encourage all women to complete an online reporting form.

A corresponding patient information leaflet on colestyramine use in pregnancy is available at


Colestyramine (cholestyramine) is an anion exchange resin that is not absorbed from the gastro-intestinal tract. Colestyramine forms an insoluble complex with bile acids in the intestine, preventing their reabsorption and resulting in a decrease in serum cholesterol and low-density lipoprotein concentrations. It is licensed for the treatment of diarrhoeal disorders, hypercholesterolaemia and pruritus associated with partial biliary obstruction and primary biliary cirrhosis. In pregnancy the drug has been used for relief from pruritus associated with intrahepatic cholestasis of pregnancy (ICP; also known as obstetric cholestasis), although current Royal College of Obstetricians and Gynaecologists (RCOG) guidelines state that colestyramine is ‘not in clinical use’ for this purpose. Colestyramine is also used in pregnancy as washout therapy for leflunomide and teriflunomide.

There are currently insufficient data to permit a meaningful risk assessment of the potential effects of colestyramine exposure in pregnancy and women should be made aware of this lack of information. However, because colestyramine is not absorbed systemically, it is not expected to have direct effects, although colestyramine may cause maternal deficiencies of fat-soluble vitamins which may lead to adverse fetal effects. In particular, maternal vitamin K deficiency (a recognised complication of ICP itself) may lead to hypoprothrombinaemia and thus bleeding disorders in the fetus and neonate. Assessment of maternal prothrombin time, appropriate maternal vitamin K supplementation and administration of vitamin K to the neonate, should be considered if treatment with colestyramine is needed in pregnancy. Current RCOG guidelines on the management of ICP recommend checking prothrombin time, even in the absence of colestyramine treatment.

Exposure to colestyramine at any stage in pregnancy would not be regarded as medical grounds for termination of pregnancy or any additional fetal monitoring. However, other risk factors which independently increase the risk of adverse pregnancy outcome may be present in individual cases. Clinicians are reminded of the importance of consideration of such factors when performing case-specific risk assessments.

This document is regularly reviewed and updated. Only use full UKTIS monographs downloaded directly from to be sure you are using the most up-to-date version. The summaries of these monographs are openly available on

This is a summary of the full UKTIS monograph for health care professionals and should not be used in isolation. The full UKTIS monograph and access to any hyperlinked related documents is available to health care professionals at

If you have a patient with exposure to a drug or chemical and require assistance in making a patient-specific risk assessment, please telephone UKTIS on 0344 892 0909 to discuss the case with a teratology specialist.

If you would like to report a pregnancy to UKTIS please click here to download our pregnancy reporting form. Please encourage all women to complete an online reporting form.

Disclaimer: Every effort has been made to ensure that this monograph was accurate and up-to-date at the time of writing, however it cannot cover every eventuality and the information providers cannot be held responsible for any adverse outcomes of the measures recommended. The final decision regarding which treatment is used for an individual patient remains the clinical responsibility of the prescriber. This material may be freely reproduced for education and not for profit purposes within the UK National Health Service, however no linking to this website or reproduction by or for commercial organisations is permitted without the express written permission of this service. This document is regularly reviewed and updated. Only use UKTIS monographs downloaded directly from or to ensure you are using the most up-to-date version.