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Bile Acid Sequestrant / Ion Exchange Resin Pregnancy: The safety of colestyramine in pregnancy and lactation has not been established, and the possibility of interference with absorption of fat-soluble vitamins should be considered.

Colestyramine (Cholestyramine)

Brand names: Questran

Colestyramine (cholestyramine) is an oral anion-exchange bile-acid sequestrant used for bile-acid diarrhoea, pruritus associated with cholestasis or partial biliary obstruction, and as a lipid-lowering agent.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: Hypercholesterolaemia / primary prevention of coronary heart disease (monotherapy): after initial introduction over a three to four week period, 3 to 6 sachets per day (each sachet contains 4 g colestyramine), given either as a single daily dose or in divided doses up to four times daily, according to dosage requirements and patient acceptability. Dosage may be modified according to response and can be increased to 9 sachets per day if necessary.
Route: Oral — must NOT be taken in its dry form. Administer mixed with water or a suitable liquid such as fruit juice and stirred to a uniform consistency; it may also be mixed with skimmed milk, thin soups, or pulpy fruits with high moisture content (e.g. apple sauce).
Frequency: Once daily, or in divided doses up to four times daily. The suggested time of administration is mealtime, but this may be modified to avoid interference with absorption of other medications.
Max: Can be increased to 9 sachets per day if necessary. 'Doses of more than 24 g a day of colestyramine resin may interfere with normal fat absorption.'
Source: eMC SPC for Colestyramine 4 g Powder for Oral Suspension (sachet = 4 g colestyramine). INTRODUCTION SCHEDULE (sachets per day, weeks 1-4) — to a final dose of 3: 1, 2, 3, 3; to a final dose of 4: 1, 2, 3, 4; to a final dose of 6: 1, 2, 3, 6. Occasional slight gastrointestinal upsets, e.g. constipation, may occur when starting; these usually pass with continued use and are minimised by starting therapy gradually. OTHER INDICATIONS: to relieve pruritus — one or two sachets daily are usually sufficient; to relieve diarrhoea — as for reduction of cholesterol, but it may be possible to reduce this dosage, and in all patients presenting with diarrhoea induced by bile acid malabsorption, if a response is not seen within 3 days then alternative therapy should be initiated. Colestyramine should NOT be used in patients with exudative or bloody diarrhoea. COMBINATION THERAPY: the cholesterol-lowering effect on total and LDL-cholesterol is enhanced when combined with an HMG-CoA reductase inhibitor (e.g. pravastatin, simvastatin, lovastatin); enhanced LDL lowering is also seen with combined nicotinic acid/colestyramine therapy, and there is evidence to support adding colestyramine to gemfibrozil in patients with high LDL-cholesterol and triglycerides and low HDL-cholesterol. ELDERLY: no dosage adjustment is necessary. ADMINISTRATION TIMING (precautionary): where concurrent drug therapy exists, such drugs should be administered at least one hour before or 4-6 hours after colestyramine. MONITORING: serum cholesterol should be determined frequently during the first few months and periodically thereafter; serum triglycerides measured periodically; the diet may require supplementation with vitamins A, D and K during prolonged high-dose administration, and folic acid supplementation should be considered in children with familial hypercholesterolaemia. Reduce the dose in patients with constipation, since colestyramine may produce impaction. EXCIPIENTS: contains 3.79 g sucrose per sachet (relevant in diabetes mellitus; not for patients with hereditary fructose intolerance, glucose-galactose malabsorption or sucrase-isomaltase insufficiency) and 97.5 mg propylene glycol-related excipient (text truncated). PAEDIATRIC: the SPC states 'Children 6 - 12 years: The initial dose is determined by the following formula:' — THE FORMULA ITSELF WAS NOT CAPTURED in the fetched text (it is rendered as an equation/image on the eMC page), so no paediatric dose has been recorded; clinician to source it. Subsequent dosage adjustment may be necessary where clinically indicated; to minimise potential gastrointestinal side effects it is desirable to begin all therapy in children with one dose daily, increasing gradually every five to seven days to the desired level for effective control. Colestyramine should NOT be used in children under 6 years — there are no data to support its use. Verify against a children's formulary. §4.4 is marked truncated at the source-fetch limit and eMC §4.5 was not included in this bundle.

Dose adjustments

Renal

No dose adjustment is stated. §4.4 warns that prolonged use of colestyramine resin in high doses may produce hyperchloraemic acidosis, since it is the chloride form of an anion exchange resin — 'This is especially true in younger and smaller patients where the relative dosage may be higher as well as in patients with renal impairment.'

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

  • Hypersensitivity to the active substance or to any of the excipients
  • Complete biliary obstruction, since colestyramine cannot be effective where bile is not secreted into the intestine
  • From §4.2: should not be used in children under 6 years — there are no data to support its use
  • From §4.2: should not be used in patients with exudative or bloody diarrhoea

Side effects

  • Constipation (very common) — usually mild and transient; predisposing factors when used as a cholesterol-lowering agent are high dose and age over 60 years; some patients require a temporary dose decrease or discontinuation
  • Abdominal discomfort, flatulence, nausea, vomiting, diarrhoea, heartburn, dyspepsia and steatorrhoea (uncommon)
  • Bleeding tendencies due to hypoprothrombinaemia (vitamin K deficiency), and vitamin A (night blindness reported rarely) and vitamin D deficiencies (uncommon); anaemia (frequency not known)
  • Anorexia and hyperchloraemic acidosis in children and patients with renal impairment (uncommon); oedema (frequency not known)
  • Intestinal obstruction (rare, reported post-marketing, including deaths in paediatric patients); rash and irritation of skin, tongue and perianal area; osteoporosis (uncommon); arthritis and backache

Interactions

  • Colestyramine may bind other drugs given concurrently and impede their absorption — the interval between administration of colestyramine and other medication should be as great as is feasible, and patients should take other drugs at least one hour before or four to six hours after colestyramine (from §4.4; eMC §4.5 was NOT included in this bundle, so the itemised UK interaction list has not been verified)
  • May interfere with the absorption of fat-soluble vitamins — the diet may require supplementation with vitamins A, D and K during prolonged high-dose administration

Clinical monograph

How it works

It binds bile acids in the gut to form an insoluble complex that is excreted in the faeces, interrupting enterohepatic recirculation and increasing hepatic conversion of cholesterol to bile acids.

Prescribing in practice

  • It binds many other drugs in the gut and reduces their absorption, so administer other medicines well before or after it, and be aware it can impair absorption of fat-soluble vitamins on prolonged use.
  • Constipation is common and it should be avoided in complete biliary obstruction, where it is ineffective.
  • Prolonged use may warrant supplementation of fat-soluble vitamins, particularly in children or with high doses.

Monitoring

Monitor lipids where used for hyperlipidaemia and consider fat-soluble vitamin status with prolonged therapy.

Counselling the patient

  • Mix the powder thoroughly with water or a suitable liquid before taking, as directed.
  • Take your other medicines at a separate time, at least an hour before or several hours after this one.
  • Tell your prescriber if you become constipated.

Evidence & guidelines

Established prescribing references support colestyramine for bile-acid diarrhoea and cholestatic pruritus, and its propensity to bind co-administered drugs is a well-recognised interaction.

Reference: NICE CG149 Jaundice in Adults; SeHCAT Guidelines; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.