Colesevelam and Glimepiride: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Glimepiride
Colesevelam
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 glimepiride exposure
Interaction Deep Dive
Colesevelam may reduce gastrointestinal absorption of glimepiride, decreasing its bioavailability. In a manufacturer study, concurrent administration with colesevelam reduced the drug exposure of glimepiride; however, changes were minimal when glimepiride was given 4 hours prior to colesevelam. In patients requiring coadministration of these agents, glimepiride should be taken at least 4 hours prior to colesevelam1.
Why it happens (mechanism)
Reduced gastrointestinal absorption of glimepiride by binding with colesevelam
Literature reports
1 report — tap to read
a) Coadministration of glimepiride 4 mg and colesevelam 3.75 g resulted in an 18% and 8% mean reduction in glimepiride AUC and Cmax, respectively. When glimepiride was given 4 hours prior to colesevelam, the mean changes in glimepiride AUC and Cmax were -6% and 3%, respectively 1.
Common questions
Can I take Colesevelam and Glimepiride together?
Decreased glimepiride exposure Always confirm with your pharmacist or prescriber before making any change.
How serious is the Colesevelam and Glimepiride 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 Colesevelam or Glimepiride 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)
- Product Information: WELCHOL oral tablets, oral suspension, colesevelam HCl oral tablets, oral suspension. Daiichi Sankyo, Inc. (per FDA), Parsippany, NJ, 2012. DailyMed
Keep reading about Glimepiride
Keep reading about Colesevelam
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