What are the side effects of Flecainide (anti-arrhythmic medication) and how long after discontinuation can they be expected to abate?

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From the Guidelines

Flecainide can cause several side effects, and it is recommended to stop the medication under medical supervision, with most side effects resolving within 2-4 days after discontinuation, and complete resolution taking up to 5-7 days due to its half-life of approximately 20 hours 1. The side effects of flecainide include dizziness, visual disturbances, headache, nausea, fatigue, heart rhythm changes, shortness of breath, and chest pain. More serious side effects may include worsening arrhythmias, heart failure symptoms, or new heart conduction problems. Some key points to consider when stopping flecainide include:

  • The drug is fully eliminated from the body after about 4-5 half-lives (3-4 days) 1.
  • Some cardiac effects may persist longer because flecainide accumulates in cardiac tissue 1.
  • Patients should never stop flecainide suddenly without medical supervision as this could trigger dangerous arrhythmias, especially in those with structural heart disease or severe arrhythmias 1.
  • If experiencing concerning side effects, contact your healthcare provider immediately rather than stopping the medication independently 1.
  • Your doctor may need to monitor you closely during medication discontinuation, particularly if you have underlying heart conditions 1. It is essential to weigh the benefits and risks of flecainide therapy, considering its efficacy in preventing recurrent atrial fibrillation and its potential side effects, and to closely monitor patients during treatment and discontinuation 1.

From the Research

Side Effects of Flecainide

The side effects of flecainide can be significant and may require discontinuation of the medication. Some common side effects include:

  • Cerebral symptoms 2
  • Gastrointestinal complaints 2
  • Bradyarrhythmias 2
  • Heart failure 2
  • Suspected pro-arrhythmia 2
  • Cardiac arrest 3
  • Dysrhythmias 3
  • Acute kidney injury (AKI) 3

Time to Stop Flecainide to See Side Effects Abate

The time it takes for side effects to abate after stopping flecainide is not well established. However, it is likely that side effects will resolve once the medication is discontinued. In one study, flecainide was discontinued in 50 patients due to side effects, and it is assumed that the side effects resolved after discontinuation 2.

Flecainide Toxicity

Flecainide toxicity can occur, especially in patients with acute kidney injury (AKI) 3. The symptoms of flecainide toxicity can be severe and may include altered mental status, hypoxia, and wide complex tachycardia. Treatment of flecainide toxicity can be lifesaving if initiated promptly 3.

Safety and Efficacy of Flecainide

The safety and efficacy of flecainide have been evaluated in several studies. One study found that flecainide was effective in preventing ventricular arrhythmias in patients with arrhythmogenic right ventricular cardiomyopathy, with a low rate of side effects 4. Another study found that a 3-month lower-dose flecainide regime did not reduce the early and late arrhythmia recurrences after catheter ablation of atrial fibrillation 5.

Clinical Use of Flecainide

Flecainide is an IC antiarrhythmic drug that is approved for the suppression of sustained ventricular tachycardia and for the acute cardioversion of atrial fibrillation 6. It is mostly used for sinus rhythm maintenance in atrial fibrillation patients without structural cardiomyopathy. The optimal clinical use of flecainide, including its indications and contraindications, and appropriate monitoring, should be based on the most recent evidence 6.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

The Case of Flecainide Toxicity: What to Look for and How to Treat.

The Journal of emergency medicine, 2020

Research

Safety and efficacy of flecainide associated with beta-blockers in arrhythmogenic right ventricular cardiomyopathy.

Europace : European pacing, arrhythmias, and cardiac electrophysiology : journal of the working groups on cardiac pacing, arrhythmias, and cardiac cellular electrophysiology of the European Society of Cardiology, 2022

Research

Three-month lower-dose flecainide after catheter ablation of atrial fibrillation.

Europace : European pacing, arrhythmias, and cardiac electrophysiology : journal of the working groups on cardiac pacing, arrhythmias, and cardiac cellular electrophysiology of the European Society of Cardiology, 2014

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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