Colestipol and Furosemide: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Furosemide
Colestipol
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 furosemide effectiveness
Interaction Deep Dive
The interference of resins with the absorption of furosemide was studied. The bioavailability of furosemide was reduced 80% with colestipol1.
Why it happens (mechanism)
Binding of furosemide by colestipol
Literature reports
1 report — tap to read
a) In a cross-over study involving six healthy volunteers, colestipol 10 g administered immediately after furosemide 40 mg resulted in a decrease in the furosemide absorption by 80%. Maximum concentration (Cmax) decreased from 1.2 mg/L to 0.17 mg/L, and the area under the concentration-time curve (AUC) of furosemide fell from 3.5 mg/L/h to 0.74 mg/L/h. The 4-hour diuretic response to furosemide was also reduced from a control value of 1510 mL to 630 mL in the presence of colestipol 1.
Common questions
Can I take Colestipol and Furosemide together?
Decreased furosemide effectiveness Always confirm with your pharmacist or prescriber before making any change.
How serious is the Colestipol and Furosemide 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 Colestipol or Furosemide 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)
- Neuvonen PJ, Kivisto K, & Hirvisalo EL: Effects of resins and activated charcoal on the absorption of digoxin, carbamazepine and frusemide. Br J Clin Pharmacol 1988; 25:229-233. PubMed
Keep reading about Furosemide
Keep reading about Colestipol
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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