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Overview: Propafenone is taken for certain heart rhythm problems. Propafenone helps your heart beat normally. Common side effects include dizziness and taste changes. Tell your healthcare provider right away if you get a fever, chills, or sore throat.

Uses

What is propafenone used for?

Propafenone is commonly used to help prevent certain types of fast, irregular heartbeats, like paroxysmal supraventricular tachycardia (PSVT) and atrial fibrillation, when these cause serious symptoms.

Propafenone is also used to treat an abnormal heartbeat or rhythm in the lower parts of the heart, called the ventricles. This is called ventricular arrhythmia. Propafenone is only for people with serious ventricular arrhythmias, such as sustained ventricular tachycardia. 

Propafenone may also be used for other conditions as determined by your healthcare provider.

How does propafenone work (mechanism of action)?

Propafenone works by blocking certain electrical signals in the heart that cause it to beat too fast or irregularly. This helps the heart beat normally again.

How is propafenone supplied (dosage forms)?

Dosage forms and strengths

  • 225 mg, 325 mg, 425 mg extended-release oral capsules
  • 150 mg, 225 mg, 300 mg oral tablets

How should I store propafenone?

Propafenone should be stored at room temperature, between 68 F to 77 F (20 C to 25 C). It can be exposed to temperatures between 59 F to 86 F (15 C to 30 C) for shorter periods of time, such as when transporting it. Store in a cool, dry place.

Side Effects

What are the most common side effects of propafenone?

The most common side effects of propafenone are listed below. Tell your healthcare provider if you have any of these side effects that bother you.

  • Dizziness
  • Feeling of skipped heartbeats
  • Change in how things taste
  • Nausea or vomiting 
  • Tiredness
  • Headache
  • Anxiety
  • Constipation

There may be other side effects of propafenone that are not listed here. Contact your healthcare provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088. In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of propafenone?

While less common, the most serious side effects of propafenone are described below, along with what to do if they happen.

Heart Rhythm Changes. Propafenone may cause serious heart rhythm problems that can lead to an irregular heartbeat and fainting. In rare cases, this may cause the heart to suddenly stop beating (cardiac arrest). Some people have a higher risk of this, including people with existing heart disease or who take other medicines that affect the heart. Get emergency help if you have any of the following signs of heart rhythm changes.

  • Chest pain
  • Shortness of breath
  • Feeling dizzy or lightheaded, or fainting
  • Changes in your heart rate or rhythm, such as a fast, slow, pounding or skipping heartbeat

Low White Blood Cell Levels (Agranulocytosis). Propafenone may cause severely low levels of types of white blood cells (called granulocytes), which is known as agranulocytosis. Granulocytes help prevent infection. Having a very low level of granulocytes increases your risk of a serious infection. Tell your healthcare provider right away if you have any of the following symptoms.

  • Fever or chills
  • Sore throat
  • Any other flu-like symptoms
  • Sores in your mouth or nose
  • Swollen lymph nodes

Heart Failure. Propafenone can cause new or worsening heart failure. The risk is higher in people who already have heart failure or a history of heart problems. Tell your healthcare provider right away if you have any of the following symptoms of heart failure.

  • Shortness of breath or trouble breathing, especially while lying down
  • Swelling in your feet, ankles, or legs
  • Unusually fast weight gain
  • Unusual tiredness

Severe Allergic Reactions. Propafenone may cause allergic reactions, which can be serious. Stop taking propafenone and get help right away if you have any of the following symptoms of a serious allergic reaction.

  • Breathing problems or wheezing
  • Racing heart
  • Fever or general ill feeling
  • Swollen lymph nodes
  • Swelling of the face, lips, mouth, tongue, or throat
  • Trouble swallowing or throat tightness
  • Itching, skin rash, or pale red bumps on the skin called hives
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain

Warnings & Precautions

Who should not use propafenone?

Allergies to Ingredients. People who are allergic to any of the following should not take propafenone.

  • Propafenone
  • Rythmol
  • Rythmol SR
  • Any of the ingredients in the specific product dispensed

Your pharmacist can tell you all of the ingredients in the specific propafenone products they stock.

Heart Failure. People who have heart failure should not take propafenone. 

Heart Block or Other Heart Rhythm Problems. People who have the following heart rhythm problems should not take propafenone unless they have a pacemaker.

  • Heart block, also called atrioventricular (AV) block
  • Sick sinus syndrome
  • Atrioventricular disorders
  • Impulse generation disorders
  • Conduction disorders

Brugada Syndrome. People who have Brugada Syndrome, a rare type of irregular heartbeat, should not take propafenone. 

Slow Heartbeat. Propafenone should not be taken if your heart is beating too slow (bradycardia).

Low Blood Pressure. Propafenone should not be taken if your blood pressure is too low (hypotension).

Breathing Problems. People with conditions that make it difficult to breathe, like asthma or COPD, should not take propafenone.

Electrolyte Imbalance. Propafenone should not be taken if the electrolyte levels in your blood are abnormal.

What should I know about propafenone before using it?

Do not take propafenone unless it has been prescribed to you by a healthcare provider. Take it as prescribed.

Do not open, chew, or crush the extended-release capsules.

Do not share propafenone with other people, even if they have the same condition as you. It may harm them.

Keep propafenone out of the reach of children.

Propafenone can affect your alertness or coordination. Do not drive or do other activities that require alertness or coordination until you know how propafenone affects you.

What should I tell my healthcare provider before using propafenone?

Tell your healthcare provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them determine if propafenone is right for you.

In particular, make sure that you discuss any of the following.

Current and Past Health Conditions. Tell your healthcare provider if you have any of the following.

Other Medicines and Supplements. Propafenone may interact with other medicines and supplements. Before taking propafenone, tell your healthcare provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section below for more details.

Pregnancy. It is not known if or how propafenone could affect pregnancy or harm an unborn baby. Tell your healthcare provider if you are or plan to become pregnant. Your healthcare provider will advise you if you should take propafenone while you are pregnant or trying to get pregnant.

Breastfeeding. Propafenone passes into breast milk. Tell your healthcare provider if you are breastfeeding or plan to breastfeed. Your healthcare provider will advise you if you should take propafenone while breastfeeding.

Interactions

Does propafenone interact with foods or drinks?

Do not drink grapefruit juice while taking propafenone. Grapefruit juice can increase your blood levels of propafenone, which may lead to serious side effects.

It is unknown if drinking alcohol will affect propafenone. The risk of dizziness may be increased if you drink alcohol while taking propafenone.

Does propafenone interact with other medicines (drug interactions)?

Always tell your healthcare provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.

In particular, make sure that you discuss if you are using any of the following before taking propafenone.

  • Propranolol (Inderal LA, Innopran XL), which is a medicine that may be used for certain heart conditions or to reduce blood pressure
  • Medicines that can cause QT prolongation, which is a potentially dangerous heart rhythm problem, such as a medicine used to control your heart rate or rhythm (antiarrhythmic)
  • Cimetidine (Tagamet HB), which is a medicine used for heartburn
  • Erythromycin, which is a medicine used for bacterial infections 
  • Rifampin, which is a medicine commonly used to treat an infection called tuberculosis
  • Digoxin (Lanoxin), which is a medicine used to treat irregular heartbeat and some types of heart failure
  • Fluoxetine, sertraline, or paroxetine, which is a medicine commonly used for anxiety and depression
  • A tricyclic antidepressant, such as desipramine, even if it is not used for depression
  • Ketoconazole, which is a medicine used for fungal infections
  • Warfarin, which is a blood thinner
  • Orlistat (Xenical, Alli), which is a medicine used for weight loss
  • Ritonavir, which is a medicine used for HIV

Some other medicines may alter the blood levels of propafenone. Tell your healthcare provider about all medicines that you take or have recently taken.

This may not be a complete list of medicines that can interact with propafenone. Always check with your healthcare provider.

Does interact with other drugs you are taking?

Enter your medication into the WebMD interaction checker

Overdose/Missed Dose

What should I do if I accidentally use too much propafenone?

If you or someone else has used too much propafenone, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

What should I do if I miss a dose of propafenone?

If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and only take the next dose. Do not take double or extra doses.