Disopyramide and Warfarin: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Warfarin
Disopyramide
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
An increased risk of bleeding
Interaction Deep Dive
One case report indicated the possibility that disopyramide may increase the effect of warfarin2, but another study 3 could not demonstrate the same response in three other patients.
Why it happens (mechanism)
Unknown
Literature reports
2 reports — tap to read
a) A patient maintained on disopyramide 400 mg daily and warfarin 3 mg daily consistently had a prothrombin time of 24 seconds. When disopyramide therapy was discontinued however, the prothrombin time fell over the next three days to 15 seconds. An increase in warfarin dosage to 8 mg daily was needed to maintain adequate anticoagulation 21.
b) Disopyramide 200 mg three times a day was administered to four patients who were receiving warfarin. There was no significant difference in the patients' response to warfarin compared to patients receiving quinidine and warfarin. The researchers refute the 1977 case reported by Haworth and Burroughs that supports an interaction 3.
Common questions
Can I take Disopyramide and Warfarin together?
An increased risk of bleeding Always confirm with your pharmacist or prescriber before making any change.
How serious is the Disopyramide and Warfarin interaction?
It is rated moderate. Can be significant — usually manageable with monitoring.
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 "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 Disopyramide or Warfarin 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)
Keep reading about Warfarin
Keep reading about Disopyramide
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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