Drug Interaction Report

Glyburide and Colesevelam: Interaction Details

A pharmacist-reviewed analysis of the Glyburide and Colesevelam interaction: the documented clinical effects, severity rating, onset, mechanism, and management considerations, with cited references throughout.

AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature

Glyburide

DiaBeta® Glynase Glynase® Micronase®
+

Colesevelam

Welchol WelChol®
Dr. Brian Staiger, PharmD, BCPS
Medically reviewed by
Dr. Brian Staiger, PharmD, BCPS
Updated Aug 8, 2026
Editorial policy · Data sources
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Interaction severity
Moderate
Can be significant — usually manageable with monitoring.
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.

Of 79 documented Glyburide interactions, 37 are rated moderate — including this one.
Onset
rapid
Evidence
probable
Severity
Moderate

What happens

Decreased glyBURIDE exposure and plasma concentrations

Interaction Deep Dive

Concurrent use of glyBURIDE and colesevelam may result in decreased bioavailability of glyBURIDE. In one study, concurrent administration of colesevelam with glyBURIDE significantly reduced the exposure of glyBURIDE; however, reductions were minimal when the glyBURIDE was given 4 hours prior to colesevelam. In patients requiring coadministration of these agents, glyBURIDE should be taken at least 4 hours prior to colesevelam. Alternatively, patients should be monitored for an adequate response to glyBURIDE therapy and the glyBURIDE dose should be adjusted appropriately1.

Why it happens (mechanism)

Reduced absorption of glyBURIDE by nonspecific binding with colesevelam

Literature reports

1 report — tap to read

a) Concurrent administration of colesevelam with glyBURIDE in participants significantly reduced levels of glyBURIDE in one study. Coadministration of glyBURIDE 3 mg and colesevelam 3.75 g resulted in a 32% and 47% mean reduction in glyBURIDE AUC and Cmax, respectively. Administration of glyBURIDE 1 hour prior to colesevelam decreased the AUC and Cmax by 20% and 15%, respectively. When glyBURIDE was given 4 hours prior to colesevelam, the mean changes in AUC and Cmax were -7% and 4%, respectively 1.

Common questions

Can I take Glyburide and Colesevelam together?

Decreased glyBURIDE exposure and plasma concentrations Always confirm with your pharmacist or prescriber before making any change.

How serious is the Glyburide and Colesevelam 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.

Questions for your pharmacist

  • Does my dose of Glyburide or Colesevelam 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 (1)

  1. Product Information: WELCHOL oral tablets, colesevelam hcl oral tablets. Daiichi Sankyo Inc, Parsippany, NJ, 2008. DailyMed
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Glyburide

Keep reading about Glyburide

All Glyburide interactions (79) Glyburide drug information
Also serious with: Moxifloxacin Ophthalmic Disopyramide Belumosudil Orlistat
Colesevelam

Keep reading about Colesevelam

All Colesevelam interactions (49) Colesevelam drug information
Also serious with: Bezafibrate Deferasirox Desogestrel Dienogest
Beyond drug–drug

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:

Glyburide + Activated Charcoal Apple Beer Grapefruit Siberian Cocklebur Sweet Orange Wine Acai + 323 more
Colesevelam + Activated Charcoal Coffee Charcoal European Mandrake Glucomannan Guar Gum Gum Arabic Slippery Elm Tragacanth + 9 more

major · moderate · minor — check everything you take with our drug–supplement interaction checker.

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This information is for education, not a substitute for professional medical advice. Do not start, stop, or change any medication without talking to your pharmacist or prescriber.