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

If you've been prescribed propafenone for a heart rhythm problem, you may have a lot of questions: What exactly does this drug do? Why did my doctor choose this one? How do I take it correctly? This guide covers everything you need to know about propafenone in plain English.

What Is Propafenone?

Propafenone is a prescription medication used to treat and prevent certain serious heart rhythm disorders (arrhythmias). It belongs to a class of drugs called Class IC antiarrhythmics, also known as Group I antiarrhythmics — specifically, sodium channel blockers. The brand name versions are

Rythmol (immediate-release) and Rythmol SR (extended-release). Generic versions of both formulations are widely available as of 2026. Propafenone was first approved by the FDA in November 1989 and has been used in cardiology for over 35 years.

What Conditions Does Propafenone Treat?

Propafenone is FDA-approved for three indications:

1. Paroxysmal Atrial Fibrillation (PAF): Propafenone helps prevent recurrent episodes of AF in patients who don't have structural heart disease. It's used for rhythm control — keeping the heart in normal sinus rhythm — rather than rate control.
2. Paroxysmal Supraventricular Tachycardia (PSVT): For patients with disabling PSVT episodes (a rapid heart rhythm starting in the upper chambers of the heart) who don't have structural heart disease.
3. Life-Threatening Ventricular Arrhythmias: For documented, life-threatening arrhythmias originating in the lower chambers of the heart (ventricles), such as sustained ventricular tachycardia.

Some cardiologists also use propafenone as a "pill-in-the-pocket" strategy — a single oral loading dose taken at the onset of an AF episode to convert the heart back to normal rhythm. This is an off-label use but is supported by clinical evidence.

Propafenone Dosage Forms and Strengths

Propafenone comes in two formulations, each with different strengths and dosing schedules:

Immediate-Release (IR) Tablets

• Strengths: 150 mg, 225 mg, and 300 mg (scored tablets)
• Dosing: typically 3 times daily, every 8 hours
• Starting dose: 150 mg every 8 hours (450 mg/day); may increase to 225 mg q8h (675 mg/day) or 300 mg q8h (900 mg/day)

Extended-Release (ER) Capsules — Rythmol SR

• Strengths: 225 mg, 325 mg, and 425 mg
• Dosing: twice daily, every 12 hours
• Starting dose: 225 mg every 12 hours; may increase every 5 days to 325 mg or 425 mg q12h
• Do NOT crush or open the extended-release capsules — swallow them whole

How to Take Propafenone Correctly

To get the most benefit from propafenone and reduce side effects, follow these guidelines:

• Take propafenone at evenly spaced intervals (every 8 hours for IR, every 12 hours for ER) to maintain stable blood levels
• Can be taken with or without food; taking with food may reduce nausea
• Avoid grapefruit and grapefruit juice — it inhibits CYP3A4 and can increase propafenone blood levels
• If you miss a dose, take it as soon as you remember — unless it's almost time for your next dose. Never double up.
• Do not stop taking propafenone without talking to your cardiologist — stopping suddenly can trigger arrhythmia recurrence

Who Should NOT Take Propafenone?

Propafenone is contraindicated (should not be used) in patients with:

• Heart failure (current or history)
• Brugada syndrome (a genetic heart rhythm condition)
• AV block or sick sinus syndrome (without a pacemaker)
• Severe hypotension or bradycardia (low blood pressure or slow heart rate)
• Severe electrolyte imbalance
• Active bronchospasm (severe asthma or COPD)
• Recent myocardial infarction (within 2 years) with structural heart disease

Is Propafenone a Controlled Substance?

No. Propafenone is not a controlled substance. It is not classified under any DEA schedule. While it is a prescription-only medication, it does not have abuse potential and is not subject to the special dispensing regulations that apply to controlled substances like opioids or benzodiazepines. You can refill propafenone without the restrictions that apply to Schedule II-IV drugs.

Finding Propafenone in Stock Near You

If you have trouble finding propafenone at your pharmacy, medfinder can help. It calls pharmacies near you to find which ones have your specific propafenone prescription in stock. You can also read our guide on how to find propafenone in stock near you for more strategies.