Flecainide and Telavancin: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Flecainide
Telavancin
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 QT interval prolongation
Interaction Deep Dive
In clinical trials, prolongation of the QT interval was observed with telavancin use. Therefore, caution is advised if telavancin is used concomitantly with other drugs that prolong the QT interval2, such as flecainide 1, as this may result in additive effects on QT interval prolongation and an increased risk of serious cardiac events, such as torsade de pointes. If concomitant therapy is required, closely monitor for QT interval prolongation.
Why it happens (mechanism)
Additive effects on QT interval prolongation
Literature reports
2 reports — tap to read
a) In 3 clinical trials, QTc prolongation greater than 60 msec was observed in 1.5% (15 of 2062) of patients treated with telavancin 10 mg/kg compared with 0.6% (6 of 2062) patients treated with vancomycin. In these studies, 21% (214 of 1029) of telavancin-treated patients and 16% (164 of 1033) of vancomycin-treated patients received concomitant medications known to prolong QTc. Of the patients experiencing QTc prolongation of greater than 60 msec, 9 telavancin-treated patients and 1 vancomycin-treated patient received concomitant medications known to prolong the QTc interval, and less than 1% in each group did not receive a concomitant medication known to prolong the QTc interval. A separate analysis revealed that 1 telavancin-treated patient and 2 vancomycin-treated patients experienced a QTc greater than 500 msec. No patients experienced a cardiac adverse event attributed to QTc prolongation 2.
b) In a randomized, double-blind, multiple-dose, positive- and placebo-controlled, parallel study, maximum QTc prolongation of 11.6 msec (upper 90% confidence limit (CL), 16 msec) and 15.1 msec (upper 90% CL, 20 msec) was observed in patients treated with telavancin 7.5 mg/kg and 15 mg/kg, respectively, compared with 21.6 msec (upper 90% CL 26 msec) in the positive-control group. Healthy subjects (n=160) were randomized to telavancin 7.5 mg/kg, telavancin 15 mg/kg, positive control, or placebo infused over 60 minutes once daily for 3 days. At the end of the infusion, the mean maximum baseline-corrected, placebo-corrected QTc prolongation estimate for telavancin 10 mg/kg (based on interpolation of the data from patients treated with telavancin 7.5 mg/kg and 15 mg/kg) was 12 to 15 msec compared with 22 msec for the positive control. One hour after infusion, the maximum QTc prolongation for telavancin-treated patients was 6 to 9 msec compared with 15 msec for the positive control 2.
Common questions
Can I take Flecainide and Telavancin together?
An increased risk of QT interval prolongation Always confirm with your pharmacist or prescriber before making any change.
How serious is the Flecainide and Telavancin interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "unspecified". The timing of this interaction is not well characterized.
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 Flecainide or Telavancin 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 (2)
- Product Information: flecainide acetate oral tablets, flecainide acetate oral tablets. Roxane Laboratories, Inc, Columbus, OH, 2009. DailyMed
- Product Information: VIBATIV IV injection, telavancin IV injection. Theravance, Inc. South San Francisco, CA, 2009.
Keep reading about Flecainide
Keep reading about Telavancin
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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