Hydrochlorothiazide and Colestipol: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Hydrochlorothiazide
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 hydrochlorothiazide concentration
Interaction Deep Dive
The absorption of hydrochlorothiazide was significantly decreased by as much as 43% with single doses of colestipol3 when administered concomitantly with colestipol 1. If coadministered is necessary, give hydrochlorothiazide 4 hours before or 4 to 6 hours after colestipol 2.
Why it happens (mechanism)
Binding of hydrochlorothiazide by colestipol in the gut
Common questions
Can I take Hydrochlorothiazide and Colestipol together?
Decreased hydrochlorothiazide concentration Always confirm with your pharmacist or prescriber before making any change.
How serious is the Hydrochlorothiazide and Colestipol 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 "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
From our Q&A
Real reader questions about these medications, each personally answered by our pharmacist:
Questions for your pharmacist
- Does my dose of Hydrochlorothiazide 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 (3)
- Product Information: COLESTID(R), FLAVORED COLESTID(R) oral suspension, colestipol hcl oral suspension. Pharmacia & Upjohn Company, New York, NY, 2006. DailyMed
- Product Information: Diovan HCT oral tablets, valsartan hydrochlorothiazide oral tablets. Novartis Pharmaceuticals Corporation (per FDA), East Hanover, NJ, 2012. DailyMed
- Product Information: Benicar HCT(TM), olmesartan medoxomil-hydrochlorothiazide. Sankyo Pharma Inc. Parsippany, NJ, 2003. DailyMed
Keep reading about Hydrochlorothiazide
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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