The short answer
Yes, folic acid can be taken with cholestyramine, and long-term cholestyramine can lower folate. The label reports reduced folate with long-term use and says folic acid supplementation should be considered in those cases; in 18 children treated for 1 to 2.5 years, blood folate fell and 5 mg of folic acid a day corrected it. Because the resin binds folic acid, take it at least 1 hour before or 4 to 6 hours after cholestyramine, the label's spacing rule for other oral medicines. No trial was found establishing a folic acid dose for adults on cholestyramine, and 5 mg is a prescription-level dose above the adult supplement upper limit, so ask the prescriber whether a folate test or supplement is needed.
What this answer covers
Folic acid (pteroylglutamic acid) in supplements, multivitamins and prenatal products, taken with cholestyramine resin powder for oral suspension.
- Supplement or preparation
- folic acid
- Medication ingredient
- cholestyramine resin
What the label says
The cholestyramine label states that reduction of serum or red cell folate has been reported over long-term administration and that supplementation with folic acid should be considered in these cases. Because the resin can bind other drugs in the gut, 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 does not give a folic acid dose or a folate-specific interval.
What the studies found
In 18 children taking cholestyramine for 1 to 2.5 years, mean serum folate fell from 7.7 to 4.4 ng/mL after more than a year, red cell folate fell too, and oral folic acid 5 mg daily reversed the drop. A 1-year placebo-controlled study in children on 8 g daily found one girl with low folate and raised homocysteine, and a dose-titration study in 20 young patients found a significant fall in mean serum folate in the females. All three studies were in children or young adults with familial hypercholesterolaemia; no comparable adult trial was found.
Why the timing matters
Cholestyramine binds folic acid strongly in laboratory tests, even at stomach acidity, and in rats fed the resin the bioavailability of folic acid fell by about a fifth while the brewers yeast folate tested was unaffected. Folic acid swallowed with the resin is likely to be trapped, so keep to the label's interval: folic acid at least 1 hour before or 4 to 6 hours after the resin.
How much folic acid, and for whom
The study that corrected folate used 5 mg daily, five times the adult upper limit of 1,000 mcg of folic acid from supplements and fortified foods. That study dose should not be started without medical supervision. No trial was found establishing an adult supplement dose during cholestyramine treatment. Ask the prescriber whether your treatment duration, diet or symptoms warrant a folate test and, if needed, which dose to use.
What to watch for
Folate deficiency develops slowly and shows as tiredness, weakness, difficulty concentrating, irritability, headache, palpitations, breathlessness or a sore tongue. Report these to the prescriber rather than starting high-dose folic acid on your own, because high doses can mask vitamin B12 deficiency.
Evidence and practical considerations
Absorption & effectiveness
Long-term cholestyramine lowers serum and red cell folate in children and young adults, and oral folic acid 5 mg daily corrected the depletion in one series; the label directs consideration of folic acid supplementation when folate falls.
- Exact scope
- Folic acid supplements; brewers yeast folate was unaffected in the animal study. 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
- Timing or duration
- Falls were seen after more than one year of treatment
What remains uncertain
- Small uncontrolled or secondary-outcome pediatric data; no adult trial; the corrective dose was a prescription-level 5 mg; full text of the key study unavailable.
Factors that may matter: Duration of cholestyramine use; Cholestyramine dose; Baseline folate intake; Age (pediatric data).
Read the supporting source summaries
Source 1: current product label
dailymed.nlm.nih.gov · Source check Sep 22, 2026
Population: People prescribed cholestyramine resin
Reduction of serum or red cell folate has been reported over long-term administration; supplementation with folic acid should be considered in these cases. 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 state a folic acid dose, how often folate falls, or a folate-specific spacing interval.
Source 2: original human study
pubmed.ncbi.nlm.nih.gov · Source check Sep 22, 2026
Population: Eighteen children with familial hypercholesterolaemia.
Mean serum folate fell from 7.7 ng/mL before treatment to 4.4 ng/mL in patients treated for over one year, with a corresponding fall in red cell folate; oral folic acid 5 mg daily overcame the depletion. Prothrombin time stayed normal; serum iron, vitamin B12, calcium and protein did not change.
How this applies: Direct evidence that folate falls with prolonged cholestyramine and that oral folic acid corrects it; pediatric doses per kilogram were higher than usual adult doses.
Eighteen children, uncontrolled, read as an abstract (numbers appear as OCR text); full text could not be retrieved. The 5 mg dose reflects the study, not a consumer recommendation.
Source 3: original human study
pubmed.ncbi.nlm.nih.gov · Source check Sep 22, 2026
Population: Ninety-six children aged 6 to 11 years, 36 randomized to cholestyramine.
One girl in the cholestyramine group had low folate with elevated homocysteine; the authors concluded folate deficiency may occur even with a low dose. Twenty-two of 36 cholestyramine subjects completed the year.
How this applies: Shows folate can fall even at 8 g daily; no folic acid was given, so it does not test supplementation.
Randomized but small with many withdrawals for taste; the abstract gives one case rather than group folate values.
Source 4: original human study
pubmed.ncbi.nlm.nih.gov · Source check Sep 22, 2026
Population: Twenty children and young adults with familial hypercholesterolaemia.
There was a significant decrease in mean serum folate in female patients; the study was designed to relate cholesterol response to dose.
How this applies: Further sign that serum folate falls on cholestyramine; no supplementation tested.
Dose-response study read as an abstract; the folate result is a secondary observation without magnitude.
Source 5: in vitro binding study
pubmed.ncbi.nlm.nih.gov · Source check Sep 22, 2026
Population: Not applicable (in vitro).
Both resins bound folic acid to a high extent; folic acid binding by cholestyramine persisted even at pH 2, where binding of the other substances dropped.
How this applies: Explains why folic acid swallowed with the resin can be trapped, which is the basis for spacing the doses.
Laboratory binding study, not a human absorption study; abstract only.
Source 6: animal study
pubmed.ncbi.nlm.nih.gov · Source check Sep 22, 2026
Population: Male weanling rats.
The relative biological value of folic acid fell to 79 with cholestyramine (standard 100), while brewers yeast folate was unaffected (88 with or without the resin).
How this applies: Animal evidence that the resin lowers folic acid bioavailability when eaten together; supports timing rather than a dose.
Rat bioassay; dose in the diet is not a human dose.
Research assessment: · Open full citations ↗
Timing & monitoring
Take folic acid at least 1 hour before or 4 to 6 hours after cholestyramine, following the label's rule for other oral drugs, because the resin binds folic acid in vitro; no folate-specific interval has been tested.
- Exact scope
- Folic acid supplements at any dose; the adult upper limit from supplements is 1,000 mcg daily. 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
- The interval comes from the label's general drug rule and binding data, not from a folic acid pharmacokinetic study.
Factors that may matter: Time between doses; Folic acid 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
Reduction of serum or red cell folate has been reported over long-term administration; supplementation with folic acid should be considered in these cases. 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 state a folic acid dose, how often folate falls, or a folate-specific spacing interval.
Source 2: in vitro binding study
pubmed.ncbi.nlm.nih.gov · Source check Sep 22, 2026
Population: Not applicable (in vitro).
Both resins bound folic acid to a high extent; folic acid binding by cholestyramine persisted even at pH 2, where binding of the other substances dropped.
How this applies: Explains why folic acid swallowed with the resin can be trapped, which is the basis for spacing the doses.
Laboratory binding study, not a human absorption study; abstract only.
Source 3: federal nutrient fact sheet
ods.od.nih.gov · Source check Sep 22, 2026
Population: General population; no cholestyramine co-use data
Folic acid is the fully oxidized monoglutamate form used in fortified foods and most supplements; the Tolerable Upper Intake Level for folate from supplements or fortified foods is 1,000 mcg daily for adults, with higher doses reserved for medical supervision. Folate deficiency causes megaloblastic anemia with weakness, fatigue, difficulty concentrating, irritability, headache, palpitations and shortness of breath.
How this applies: Defines the supplement, its upper limit and deficiency signs; no cholestyramine data.
The fact sheet lists methotrexate and antiepileptics as interacting drugs; cholestyramine is not mentioned.
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 Folic acid article from inspected current labeling and original sources, with uncertainty stated. |
Article revision: f13ffbd7c019124f
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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