What Is Flecainide? Uses, Dosage, and What You Need to Know in 2026

Flecainide is a prescription cardiac medication that has been helping patients control dangerous heart rhythm disorders since the FDA approved it in 1984. If you've been prescribed flecainide — or are considering it — here's everything you need to know about what it is, what it treats, and how to take it safely.

What Is Flecainide?

Flecainide acetate (brand name: Tambocor) is a Class IC antiarrhythmic agent — a type of medication that stabilizes abnormal electrical activity in the heart. It belongs to the broader category of Group I antiarrhythmics and is used to prevent and treat dangerous heart rhythm disorders (arrhythmias).

The brand-name Tambocor was originally developed by 3M Pharmaceuticals and approved by the FDA in 1984. When its patent expired in 2004, generic versions became widely available. Today, generic flecainide acetate is the far more common form and is functionally identical to Tambocor.

In 2023, flecainide was the 223rd most prescribed medication in the United States, with over 1 million prescriptions dispensed — making it a well-established medication with a long safety record in appropriate patients.

What Conditions Does Flecainide Treat?

Flecainide is FDA-approved for three main indications in patients without structural heart disease:

• Paroxysmal supraventricular tachycardia (PSVT): Including AVNRT (AV nodal reentrant tachycardia) and AVRT (AV reentrant tachycardia), as well as other SVTs causing disabling symptoms.
• Paroxysmal atrial fibrillation/flutter (PAF): Flecainide is widely used to maintain normal sinus rhythm in patients with intermittent AFib. It can also be used as a "pill-in-the-pocket" for patients with infrequent episodes — a single dose taken at symptom onset to cardiovert the arrhythmia.
• Documented sustained ventricular tachycardia (VT): For life-threatening VT only, and only when initiated in a hospital setting with cardiac monitoring.

Importantly, flecainide is not recommended for patients with structural heart disease (such as a history of heart attack, heart failure, or cardiomyopathy), and it is not approved for chronic (persistent or permanent) atrial fibrillation.

Flecainide Dosage Forms and Strengths

Flecainide is available as oral tablets in three strengths:

• 50 mg tablets
• 100 mg tablets
• 150 mg tablets

Flecainide is also available as an intravenous (IV) injection in some countries, though this form is not widely available in the U.S.

Typical Flecainide Dosing

Flecainide is typically taken twice daily, 12 hours apart. Your doctor will start you at the lowest effective dose and increase gradually — no more than every 4 days — because it takes 3–5 days to reach steady-state plasma levels.

• PAF/PSVT starting dose: 50 mg every 12 hours; maximum 300 mg/day
• Sustained VT starting dose: 100 mg every 12 hours; maximum 400 mg/day

You can take flecainide with or without food, but taking it at the same time each day is important to maintain consistent blood levels. Milk may slow absorption slightly and should not be consumed immediately before doses in infants (this is mainly relevant for pediatric use).

Is Flecainide a Controlled Substance?

No. Flecainide is not a controlled substance and is not scheduled by the DEA. This means it can be prescribed without the special requirements that apply to opioids, benzodiazepines, or stimulants. Prescriptions can be refilled or transferred to different pharmacies freely.

What Does Flecainide Cost in 2026?

Generic flecainide retail prices range from approximately $22–$94 per month depending on the strength (100 mg tends to be cheapest; 50 mg is often higher in price). With discount programs like GoodRx or SingleCare, the price drops to $11–$15 per month — an 86% savings off retail. Most insurance plans cover it at Tier 1 or Tier 2 with a $0–$20 copay.

Key Things to Know When Taking Flecainide

• Never stop abruptly. Your arrhythmia can return. Always contact your cardiologist before stopping.
• Keep your monitoring appointments. ECGs, drug level checks, and kidney/liver labs are important safety monitoring — don't skip them.
• Tell all providers you take flecainide. Flecainide has over 390 documented drug interactions. This is crucial when getting prescriptions from multiple providers.
• Refill early. Pharmacy availability can be inconsistent. Start looking for your refill 5–7 days before you run out.

Want to understand how flecainide works at the cellular level? Read our deep dive into flecainide's mechanism of action.