The short answer
Yes, with timing. Cholestyramine binds bile acids and can reduce absorption of vitamin A taken at the same time: in 14 healthy volunteers, 12 g of cholestyramine added to a vitamin A-containing meal cut the expected rise in blood vitamin A by about 60 percent. Take vitamin A at least 1 hour before or 4 to 6 hours after cholestyramine, which is the label's spacing rule for other oral medicines. Whether you need extra vitamin A is less clear: in children treated for up to 2 years, levels fell but stayed in the normal range, and the label suggests considering water-miscible forms with long-term use. Do not exceed the upper intake level for preformed vitamin A without medical advice.
What this answer covers
Vitamin A as retinol or retinyl esters in supplements, multivitamins and prenatal products, taken with cholestyramine resin powder for oral suspension. Beta-carotene products were not studied.
- Supplement or preparation
- vitamin A
- Medication ingredient
- cholestyramine resin
What the label says
The label states that cholestyramine may prevent absorption of fat-soluble vitamins such as A, D, E and K, that supplementation with water-miscible or parenteral forms should be considered when the resin is given for long periods, and that one case of night blindness from vitamin A deficiency has been reported. For any other drug it advises dosing at least 1 hour before or 4 to 6 hours after the resin, or at as great an interval as possible. The pregnancy section warns that regular prenatal supplementation may not be adequate.
What the studies show
The clearest result is an absorption test in 14 healthy adults: 12 g of cholestyramine taken with a vitamin A-containing meal reduced the expected rise in serum vitamin A by 59.5 percent. Over the longer term, 18 children on cholestyramine for up to 2.5 years had a significant fall in serum vitamin A that stayed within the normal range, and in a 2-year adult study serum retinol rose with diet or statins but not in the eight people taking cholestyramine. No adult trial comparing vitamin A supplementation during cholestyramine treatment was found.
Timing is the practical step
The absorption test shows what happens when vitamin A and the resin arrive in the gut together. The label's rule for other oral medicines, at least 1 hour before or 4 to 6 hours after cholestyramine, is the only stated interval; no study has tested a vitamin A-specific gap. Taking the vitamin with a meal that is well separated from the resin dose fits both the label and how vitamin A is absorbed.
Do you need more vitamin A
The studies reviewed do not establish a routine need for extra vitamin A. The pediatric authors judged routine fat-soluble vitamin supplements unnecessary and recommended measuring vitamins A and E at intervals. The label advises considering water-miscible or parenteral supplements during long-term cholestyramine use. Ask the prescriber whether testing or supplementation is appropriate for you. Preformed vitamin A can accumulate, and its adult upper intake level is 3,000 mcg RAE daily.
What to watch for
Difficulty seeing in dim light is the first sign of vitamin A deficiency and is the effect reported on the label. Tell the prescriber if it occurs, particularly after years of cholestyramine, in pregnancy, or with a bowel or liver condition that already limits fat absorption.
Evidence and practical considerations
Absorption & effectiveness
Cholestyramine taken with vitamin A sharply reduces its absorption (about 60 percent lower serum rise in a test meal); long-term use produced measurable but sub-clinical falls in serum vitamin A in children and a blunted retinol rise in adults, and the label lists a case of night blindness.
- Exact scope
- Retinol and retinyl ester supplements; carotenoid products not studied. with Cholestyramine resin powder for oral suspension (generic products, Questran and Prevalite) at any dose; the interaction happens in the gut because the resin is not absorbed.
- Medication form and route
- oral medication; oral supplement
What remains uncertain
- One acute absorption test in healthy adults, one small uncontrolled pediatric series and a small non-randomized adult subgroup; no trial of supplementation.
Factors that may matter: Time between doses; Duration of cholestyramine use; Underlying fat malabsorption; Pregnancy.
Read the supporting source summaries
Source 1: current product label
dailymed.nlm.nih.gov · Source check Sep 22, 2026
Population: People prescribed cholestyramine resin
Because the resin binds bile acids it may interfere with normal fat digestion and absorption and may prevent absorption of fat-soluble vitamins such as A, D, E and K; with long-term use, supplementation with water-miscible or parenteral forms should be considered. Vitamin A deficiency (one case of night blindness) is listed among less frequent adverse reactions, and the pregnancy section warns that regular prenatal supplementation may not be adequate. The label tells patients to take other drugs at least 1 hour before or 4 to 6 hours after cholestyramine, or at as great an interval as possible; it gives no vitamin-specific interval.
How this applies: Exact cholestyramine resin (RxCUI 2447) as oral powder for suspension; the innovator Questran label captured in this batch carries the same folate, vitamin K, fat-soluble vitamin and spacing wording.
The label does not quantify how often vitamin A falls, name a dose, or give a vitamin-specific interval; the spacing rule is written for other drugs.
Source 2: original human study
pubmed.ncbi.nlm.nih.gov · Source check Sep 22, 2026
Population: Fourteen healthy volunteers.
Cholestyramine reduced the expected rise in serum vitamin A by 59.5 percent (p < 0.001); lignin, a comparator binder, had no significant effect in 12 subjects.
How this applies: Direct evidence that vitamin A taken together with cholestyramine is much less well absorbed; the basis for separating the doses.
Single-meal absorption test in healthy people; it measures the acute blockade, not long-term vitamin A status; abstract only, full text could not be retrieved.
Source 3: original human study
pubmed.ncbi.nlm.nih.gov · Source check Sep 22, 2026
Population: Eighteen children with familial hypercholesterolaemia.
Mean serum vitamin A and E fell significantly over the first two years but stayed within the normal range; the authors judged routine fat-soluble vitamin administration unnecessary but advised measuring prothrombin time and vitamins A and E at intervals.
How this applies: Shows a measurable but sub-clinical fall in vitamin A over 2 years without supplementation.
Eighteen children, uncontrolled, abstract only; pediatric weight-based doses.
Source 4: original human study
pubmed.ncbi.nlm.nih.gov · Source check Sep 22, 2026
Population: One hundred and two adults with primary hypercholesterolemia, eight on cholestyramine.
Across all 102 subjects serum retinol rose over 2 years; it increased in the diet and statin groups but not in the fibrate and cholestyramine groups.
How this applies: Weak adult signal that cholestyramine blunts a rise in retinol seen with other treatments; it does not show deficiency.
Only eight subjects took cholestyramine; non-randomized comparison; abstract truncated.
Research assessment: · Open full citations ↗
Timing & monitoring
Take vitamin A at least 1 hour before or 4 to 6 hours after cholestyramine, the label's general interval for oral drugs; the acute absorption test supports separating the doses, and the adult upper limit for preformed vitamin A is 3,000 mcg daily.
- Exact scope
- Retinol and retinyl ester supplements at any dose. with Cholestyramine resin powder for oral suspension (generic products, Questran and Prevalite) at any dose; the interaction happens in the gut because the resin is not absorbed.
- Medication form and route
- oral medication; oral supplement
What remains uncertain
- No vitamin A-specific interval has been tested; the label rule is written for other drugs.
Factors that may matter: Time between doses; Vitamin A dose; Other medicines taken with the resin.
Read the supporting source summaries
Source 1: current product label
dailymed.nlm.nih.gov · Source check Sep 22, 2026
Population: People prescribed cholestyramine resin
Because the resin binds bile acids it may interfere with normal fat digestion and absorption and may prevent absorption of fat-soluble vitamins such as A, D, E and K; with long-term use, supplementation with water-miscible or parenteral forms should be considered. Vitamin A deficiency (one case of night blindness) is listed among less frequent adverse reactions, and the pregnancy section warns that regular prenatal supplementation may not be adequate. The label tells patients to take other drugs at least 1 hour before or 4 to 6 hours after cholestyramine, or at as great an interval as possible; it gives no vitamin-specific interval.
How this applies: Exact cholestyramine resin (RxCUI 2447) as oral powder for suspension; the innovator Questran label captured in this batch carries the same folate, vitamin K, fat-soluble vitamin and spacing wording.
The label does not quantify how often vitamin A falls, name a dose, or give a vitamin-specific interval; the spacing rule is written for other drugs.
Source 2: original human study
pubmed.ncbi.nlm.nih.gov · Source check Sep 22, 2026
Population: Fourteen healthy volunteers.
Cholestyramine reduced the expected rise in serum vitamin A by 59.5 percent (p < 0.001); lignin, a comparator binder, had no significant effect in 12 subjects.
How this applies: Direct evidence that vitamin A taken together with cholestyramine is much less well absorbed; the basis for separating the doses.
Single-meal absorption test in healthy people; it measures the acute blockade, not long-term vitamin A status; abstract only, full text could not be retrieved.
Source 3: federal nutrient fact sheet
ods.od.nih.gov · Source check Sep 22, 2026
Population: General population; no cholestyramine co-use data
Vitamin A comprises retinol and retinyl esters; the Tolerable Upper Intake Level for preformed vitamin A is 3,000 mcg daily for adults. Night blindness is the first sign of deficiency, and frank deficiency is rare in the United States. The interactions section names orlistat, another drug that reduces fat-soluble vitamin absorption, and retinoids; cholestyramine is not mentioned.
How this applies: Defines the supplement, its upper limit and deficiency signs.
General nutrient guidance; no cholestyramine data.
Research assessment: · Open full citations ↗
Review and change history
- Publication status
- Published research summary
- Clinical review
- Not yet recorded
| Date | Update |
|---|---|
| Editorial update | |
| Source-checked release edit clarified study design, exact evidence scope and practical wording. This research edit does not constitute clinical approval. | |
| Research summary published | |
| Article prepared | |
| Prepared exact cholestyramine resin and Vitamin A article from inspected current labeling and original sources, with uncertainty stated. |
Article revision: d05c721969047d91
This guide brings together the evidence records used by our interaction checker. Each finding retains its own preparation limits, research date, and source summaries.
Full citations require verification. Reading this answer and the source summaries does not.
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