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Rythmol SR

Generic Name: propafenone (proe PAF e none)
Brand Name: Rythmol, Rythmol SR

Medically reviewed on July 19, 2018

What is Rythmol SR?

Rythmol SR is in a group of drugs called Class IC anti-arrhythmics. It affects the way your heart beats.

Rythmol SR is used in certain situations to prevent serious heart rhythm disorders.

Rythmol SR may also be used for purposes not listed in this medication guide.

Important Information

You should not use this medication if you have untreated or uncontrolled congestive heart failure, a heart condition called "sick sinus syndrome" or "AV block" (unless you have a pacemaker), slow heartbeats or severely low blood pressure, an electrolyte imbalance, a breathing disorder such as asthma, or if you have recently had a heart attack.

Rythmol SR may cause a new or worsening heartbeat pattern. Call your doctor at once if you have a headache and chest pain with severe dizziness, fainting, and fast or pounding heartbeats.

Before taking this medicine

You should not use Rythmol SR if you are allergic to it, or if you have:

  • heart failure, or if you have recently had a heart attack;

  • a genetic heart condition, especially a certain heart rhythm disorder called Brugada syndrome;

  • a serious heart condition such as "sick sinus syndrome" or "AV block" (unless you have a pacemaker);

  • severe low blood pressure, or history of slow heart beats that have caused you to faint;

  • a severe or uncontrolled electrolyte imbalance (such as low levels of potassium in your blood); or

  • a breathing disorder such as severe COPD (chronic obstructive pulmonary disease).

To make sure Rythmol SR is safe for you, tell your doctor if you have:

  • heart disease or prior heart attack;

  • a breathing disorder;

  • liver or kidney disease;

  • lupus;

  • myasthenia gravis; or

  • if you have ever had an abnormal blood test called Antinuclear Antibody Test or ANA.

It is not known whether Rythmol SR will harm an unborn baby. Tell your doctor if you are pregnant.

Rythmol SR may affect fertility (ability to have children) in men. Talk with your doctor if you have concerns about this risk.

Propafenone can pass into breast milk and may harm a nursing baby. You should not breast-feed while using this medicine.

How should I take Rythmol SR?

Follow all directions on your prescription label. Your doctor may occasionally change your dose to make sure you get the best results. Do not take this medicine in larger or smaller amounts or for longer than recommended.

You may take Rythmol SR with or without food.

Your heart function may need to be checked with an electrocardiograph or ECG (sometimes called an EKG), before and during treatment with Rythmol SR.

You may have very low blood pressure while taking this medication. Call your doctor if you are sick with vomiting or diarrhea, extreme thirst, loss of appetite, or if you are sweating more than usual.

While using Rythmol SR, you may need frequent blood tests.

Store at room temperature away from moisture, heat, and light. Keep the bottle tightly closed when not in use.

What happens if I miss a dose?

Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

What should I avoid while taking Rythmol SR?

Grapefruit and grapefruit juice may interact with Rythmol SR and lead to unwanted side effects. Avoid the use of grapefruit products while taking this medicine.

Rythmol SR side effects

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have:

  • shortness of breath (even with mild exertion), swelling, rapid weight gain;

  • headache with chest pain and severe dizziness, fainting, fast or pounding heartbeats;

  • sudden weakness or ill feeling, fever, chills, sore throat, mouth sores, red or swollen gums, trouble swallowing;

  • confusion, unusual thoughts or behavior;

  • seizure; or

  • slow heart rate, weak pulse, fainting, slow breathing (breathing may stop).

Common side effects may include:

  • irregular heartbeats;

  • nausea, vomiting, constipation;

  • headache, dizziness, tired feeling; or

  • unusual or unpleasant taste in your mouth.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

See also: Side effects (in more detail)

What other drugs will affect Rythmol SR?

Many drugs can interact with Rythmol SR. Not all possible interactions are listed here. Tell your doctor about all your current medicines and any you start or stop using, especially:

This list is not complete and many other drugs can interact with Rythmol SR. This includes prescription and over-the-counter medicines, vitamins, and herbal products. Give a list of all your medicines to any healthcare provider who treats you.

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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