Dofetilide and Triamterene: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Triamterene
Dofetilide
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
Increased dofetilide exposure and an increased risk of QT interval prolongation, and an increased risk of torsades de pointes
Interaction Deep Dive
Concomitant use of dofetilide and triamterene alone or in combination with hydroCHLOROthiazide is contraindicated. Coadminister dugs secreted via renal cationic secretion, like triamterene with care, as they may increase dofetilide exposure1.
Why it happens (mechanism)
Inhibition of renal cationic secretion
Literature reports
1 report — tap to read
a) Concomitant use of hydroCHLOROthiazide 50 mg QD or hydroCHLOROthiazide/triamterene 50/100 mg QD with dofetilide 500 mg QD for 5 days resulted in increase in dofetilide AUC and Cmax by 27% and 21%, respectively in patients receiving hydroCHLOROthiazide alone. In patients receiving hydroCHLOROthiazide in combination with triamterene, dofetilide AUC and Cmax increased by 30% and 16%, respectively 1.
Common questions
Can I take Dofetilide and Triamterene together?
Increased dofetilide exposure and an increased risk of QT interval prolongation, and an increased risk of torsades de pointes Always confirm with your pharmacist or prescriber before making any change.
How serious is the Dofetilide and Triamterene interaction?
It is rated contraindicated. These should generally not be used together.
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 Dofetilide or Triamterene 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 a safer alternative to one of these medications for me?
References (1)
- Product Information: Dofetilide oral capsules, dofetilide oral capsules. Granules Pharmaceuticals Inc. (per DailyMed), Chantilly, VA, 2025. DailyMed
Keep reading about Triamterene
Keep reading about Dofetilide
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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