Cardiovascular
Bile-acid sequestrants
Colestyramine, colesevelam, colestipol — Older cholesterol-lowering drugs, also useful for bile-acid diarrhoea and itch.
Education and reference only. This is a plain-language class overview — it deliberately contains no doses. Always check the current Summary of Product Characteristics (SmPC), the BNF and your local formulary before prescribing or administering any medicine.
What it is
Bile-acid sequestrants lower cholesterol and are also used to treat bile-acid diarrhoea and the itch associated with some liver conditions. They act entirely within the gut and are not absorbed into the body.
How it works
They bind bile acids in the intestine so these are excreted rather than reabsorbed. The liver then uses more cholesterol to make replacement bile acids, lowering blood cholesterol. In bile-acid diarrhoea, binding the excess bile acids stops them irritating the bowel.
In practice
In practice bile-acid sequestrants are used less often now for cholesterol (statins and ezetimibe are easier), but they keep a valuable role in two areas: relieving bile-acid diarrhoea (for example after gallbladder surgery or in some bowel conditions) and easing the itch of bile build-up in liver disease, as well as cholesterol-lowering where other drugs are unsuitable or in pregnancy. The defining practical problem is that they bind not just bile acids but many other drugs in the gut — including levothyroxine, digoxin, warfarin and fat-soluble vitamins — reducing their absorption, so other medicines are taken at least an hour before or four to six hours after. They are not absorbed themselves, which makes them safe in pregnancy, but they commonly cause constipation, bloating and an unpalatable, gritty texture that limits adherence; with prolonged use, fat-soluble vitamin levels may need attention.
Examples
Practical use
How to take it & use it well
- Colestyramine is a powder mixed with water or soft food, taken by mouth, used to lower cholesterol and to treat certain types of diarrhoea linked to bile acids.
- Mix the powder thoroughly with plenty of liquid and drink it down; it should not be taken dry.
- It can bind to many other medicines and reduce their absorption, so take other tablets well before or several hours after it.
- Build up to your full amount gradually and drink plenty of fluids to reduce constipation and bloating.
- Take fat-soluble vitamins separately if advised, as long-term use can affect their absorption.
- Keep taking it regularly as prescribed, and tell your team if constipation becomes a problem.
Common uses
- Bile-acid diarrhoea (e.g. after gallbladder removal)
- Itch from bile build-up in liver disease
- Cholesterol-lowering where statins are unsuitable, including pregnancy
Monitoring
- Symptom or lipid response
- Timing of other medicines around the dose
- Fat-soluble vitamins with long-term use
Weighing it up
Advantages & disadvantages
Advantages
- Lowers cholesterol by removing bile acids and prompting the body to use up more cholesterol.
- Very effective for diarrhoea caused by bile-acid malabsorption.
- Not absorbed into the body, so it acts within the gut.
- Can be combined with other cholesterol treatments when needed.
Disadvantages
- Commonly causes constipation, bloating and wind.
- Binds many other medicines, reducing their effect unless doses are separated in time.
- The powder texture and taste can be unpleasant.
- Long-term use can reduce absorption of fat-soluble vitamins.
- Must never be taken dry, as it can swell and cause choking.
Key safety principles
What to watch for
- Bind many other drugs (e.g. levothyroxine, digoxin, warfarin) and fat-soluble vitamins — take other medicines well apart (about 1 hour before or 4–6 hours after).
- Commonly cause constipation, bloating and poor palatability, limiting adherence.
- With prolonged use, fat-soluble vitamin levels may need monitoring; not absorbed, so usable in pregnancy.
Key interactions
What to avoid or check alongside
- Reduces absorption of many medicines, including warfarin, levothyroxine, digoxin and some diuretics, so these must be taken well apart from it.
- Can reduce absorption of fat-soluble vitamins A, D, E and K with long-term use.
- May reduce the effect of other oral medicines generally, so timing is important for everything you take.
- Can affect the action of warfarin in both directions, so anticoagulation may need closer monitoring.
Patient & carer advice
- Take your other medicines well apart from this — at least an hour before or several hours after
- Mixing it well and building up slowly helps with the taste and bloating
- Tell us if constipation is troublesome
Use with
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Answers
Bile-acid sequestrants: frequently asked questions
Why do I have to space out my other medicines?
Colestyramine binds to many other medicines in the gut and stops them being absorbed. Taking other tablets well before, or several hours after, colestyramine helps make sure they still work.
How should I take the powder?
Mix the powder thoroughly with plenty of water, juice or soft food and drink it down. Never take it dry, as it can swell and cause choking, and drinking plenty helps reduce constipation.
What is bile-acid diarrhoea and how does colestyramine help?
Bile-acid diarrhoea happens when bile acids are not properly reabsorbed and irritate the bowel. Colestyramine binds these bile acids, which can greatly reduce the diarrhoea.
Will I need extra vitamins?
Long-term use can reduce absorption of fat-soluble vitamins A, D, E and K. Your team may advise supplements, taken separately from the colestyramine, and will monitor you if needed.
What can I do about constipation?
Constipation, bloating and wind are common. Building up the dose slowly, drinking plenty of fluids, and eating enough fibre can help. Tell your team if it remains a problem.
Authoritative sources
Always verify against the source
This overview is for orientation. For doses, interactions, contra-indications and the full monograph, use:
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