Gemfibrozil and Colestipol: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Colestipol
Gemfibrozil
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 gemfibrozil effectiveness
Interaction Deep Dive
Concurrent use of colestipol and gemfibrozil may result in reduced bioavailability of gemfibrozil if they are administered at the same time1.
Why it happens (mechanism)
Decreased gemfibrozil absorption
Literature reports
1 report — tap to read
a) Colestipol decreases the oral bioavailability of gemfibrozil when administered concomitantly 1. Ten patients with elevated serum cholesterol and triglycerides received oral gemfibrozil 600 mg in 4 regimens: alone, with colestipol 5 g 2 hours before or 2 hours after, and concomitantly. Each segment of the study was separated by 3 days with no drug. The area under the plasma concentration-time curve (AUC) was significantly decreased (by 30%) when the agents were administered together but no statistically significant difference occurred when they were administered 2 hours apart.
Common questions
Can I take Gemfibrozil and Colestipol together?
Decreased gemfibrozil effectiveness Always confirm with your pharmacist or prescriber before making any change.
How serious is the Gemfibrozil and Colestipol interaction?
It is rated minor. Usually limited clinical impact.
How quickly could this interaction happen?
The documented onset is "delayed". Effects tend to build up gradually over days to weeks.
How strong is the evidence for this interaction?
The evidence is graded "established". Well documented — supported by controlled studies or strong clinical data.
From our Q&A
Real reader questions about these medications, each personally answered by our pharmacist:
Questions for your pharmacist
- Does my dose of Gemfibrozil or Colestipol 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)
- Forland SC, Feng Y, & Cutler RE: Apparent reduced absorption of gemfibrozil when given with colestipol. J Clin Pharmacol 1990; 30:29-32. PubMed
Keep reading about Colestipol
Keep reading about Gemfibrozil
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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