Propranolol and Cholestyramine Resin: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Cholestyramine Resin
Propranolol
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
What happens
Decreased propranolol exposure
Interaction Deep Dive
Coadministration of cholestyramine and propranolol may reduce propranolol concentration by up to 50%2, or delay propranolol absorption. Administer at least 1 hour before or 4 to 6 hours after cholestyramine to avoid altering absorption 1.
Why it happens (mechanism)
Decreased propranolol bioavailability
Common questions
Can I take Propranolol and Cholestyramine Resin together?
Decreased propranolol exposure Always confirm with your pharmacist or prescriber before making any change.
How serious is the Propranolol and Cholestyramine Resin interaction?
It is rated moderate. Can be significant — usually manageable with monitoring.
How quickly could this interaction happen?
The documented onset is "rapid". Effects can appear quickly, often within about 24 hours of combining the drugs.
How strong is the evidence for this interaction?
The evidence is graded "probable". Good supporting evidence, though not definitively proven.
From our Q&A
Real reader questions about these medications, each personally answered by our pharmacist:
Questions for your pharmacist
- Does my dose of Propranolol or Cholestyramine Resin need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there anything you'd monitor while I'm on both?
References (2)
- Product Information: Cholestyramine oral suspension, cholestyramine oral suspension. ANI Pharmaceuticals Inc (per DailyMed), Baudette, MN, 2019. DailyMed
- Product Information: Propranolol HCl oral tablets, propranolol HCl oral tablets. Amneal Pharmaceuticals LLC (per DailyMed), Bridgewater, NJ, 2019. DailyMed
Keep reading about Cholestyramine Resin
Keep reading about Propranolol
These medications also interact with supplements
Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
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