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Last reviewed on RxList: 10/18/2016
Rythmol Side Effects Center
Heart Disease:The No. 1 Killer in the U.S.

Last reviewed on RxList 10/12/2016

Rythmol (propafenone hydrochloride) is a Class IC anti-arrhythmic used to prevent serious heart rhythm disorders. Rythmol is available in generic form. Common side effects of Rythmol include:

  • dizziness,
  • headache,
  • metallic/salty/unpleasant/unusual taste in the mouth,
  • nausea,
  • vomiting,
  • constipation,
  • loss of appetite,
  • anxiety,
  • loss of balance or coordination,
  • tiredness,
  • fatigue,
  • ringing in your ears,
  • unusual dreams,
  • blurred vision,
  • weakness,
  • shortness of breath,
  • fast or slow heartbeat,
  • palpitations,
  • tremor,
  • diarrhea, or
  • warmth, redness, or tingly feeling under your skin.

The initial dose of Rythmol is 150 mg given every eight hours (450 mg/day). Dosage may be increased at a minimum of 3 to 4 day intervals to 225 mg every 8 hours (675 mg/day). Rythmol may interact with cimetidine, digoxin, ketoconazole, orlistat, quinidine, rifampin, blood thinners, antidepressant, HIV or AIDS medication, other heart rhythm medications, medicines to treat psychiatric disorders, or beta-blockers. Tell your doctor all medications and supplements you use. During pregnancy, Rythmol should be used only when prescribed. Rythmol passes into breast milk and may have undesirable effects on a nursing infant. Consult your doctor before breastfeeding.

Our Rythmol (propafenone hydrochloride) Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

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.

Rythmol Consumer Information
Heart Disease:The No. 1 Killer in the U.S.

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 a serious side effect such as:

  • feeling short of breath, even with mild exertion;
  • swelling, rapid weight gain;
  • chest pain, rapid heart rate, pounding heartbeats or fluttering in your chest;
  • fever, chills, sore throat, flu symptoms, weakness;
  • confusion, unusual thoughts or behavior;
  • seizure; or
  • slow heart rate, weak pulse, fainting, slow breathing (breathing may stop).

Less serious side effects may include:

  • dizziness, anxiety, loss of balance or coordination;
  • unusual or unpleasant taste in your mouth;
  • nausea, vomiting, constipation, loss of appetite;
  • warmth, redness, or tingly feeling under your skin;
  • headache;
  • tired feeling;
  • ringing in your ears;
  • unusual dreams; or
  • blurred vision.

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.

Read the entire detailed patient monograph for Rythmol (Propafenone)

Rythmol Professional Information
Heart Disease:The No. 1 Killer in the U.S.


Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.

Adverse reactions associated with RYTHMOL occur most frequently in the gastrointestinal, cardiovascular, and central nervous systems. About 20% of patients treated with RYTHMOL have discontinued treatment because of adverse reactions.

Adverse reactions reported for > 1.5% of 474 SVT patients who received RYTHMOL in U.S. clinical trials are presented in Table 1 by incidence and percent discontinuation, reported to the nearest percent.

Table 1: Adverse Reactions Reported for > 1.5% of SVT Patients

(N = 480)
% of Pts. Who Discontinued
Unusual Taste 14% 1.3%
Nausea and/or Vomiting 11% 2.9%
Dizziness 9% 1.7%
Constipation 8% 0.2%
Headache 6% 0.8%
Fatigue 6% 1.5%
Blurred Vision 3% 0.6%
Weakness 3% 1.3%
Dyspnea 2% 1.0%
Wide Complex Tachycardia 2% 1.9%
CHF 2% 0.6%
Bradycardia 2% 0.2%
Palpitations 2% 0.2%
Tremor 2% 0.4%
Anorexia 2% 0.2%
Diarrhea 2% 0.4%
Ataxia 2% 0.0%

In controlled trials in patients with ventricular arrhythmia, the most common reactions reported for RYTHMOL and more frequent than on placebo were unusual taste, dizziness, first degree AV block, intraventricular conduction delay, nausea and/or vomiting, and constipation. Headache was relatively common also, but was not increased compared to placebo. Other reactions reported more frequently than on placebo or comparator and not already reported elsewhere included anxiety, angina, second degree AV block, bundle branch block, loss of balance, congestive heart failure, and dyspepsia.

Adverse reactions reported for ≥ 1% of 2,127 ventricular arrhythmia patients who received propafenone in U.S. clinical trials were evaluated by daily dose. The most common adverse reactions appeared dose-related (but note that most patients spent more time at the larger doses), especially dizziness, nausea and/or vomiting, unusual taste, constipation, and blurred vision. Some less common reactions may also have been dose-related such as first degree AV block, congestive heart failure, dyspepsia, and weakness. Other adverse reactions included rash, syncope, chest pain, abdominal pain, ataxia, and hypotension.

In addition, the following adverse reactions were reported less frequently than 1% either in clinical trials or in marketing experience. Causality and relationship to propafenone therapy cannot necessarily be judged from these events.

Cardiovascular System: Atrial flutter, AV dissociation, cardiac arrest, flushing, hot flashes, sick sinus syndrome, sinus pause or arrest, supraventricular tachycardia.

Nervous System: Abnormal dreams, abnormal speech, abnormal vision, confusion, depression, memory loss, numbness, paresthesias, psychosis/mania, seizures (0.3%), tinnitus, unusual smell sensation, vertigo.

Gastrointestinal: Cholestasis, elevated liver enzymes (alkaline phosphatase, serum transaminases), gastroenteritis, hepatitis.

Hematologic: Agranulocytosis, anemia, bruising, granulocytopenia, leukopenia, purpura, thrombocytopenia.

Other: Alopecia, eye irritation, impotence, increased glucose, positive ANA (0.7%), muscle cramps, muscle weakness, nephrotic syndrome, pain, pruritus.

Postmarketing Experience

The following adverse reactions have been identified during post-approval use of RYTHMOL. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.

Gastrointestinal: A number of patients with liver abnormalities associated with propafenone therapy have been reported in post-marketing experience. Some appeared due to hepatocellular injury, some were cholestatic and some showed a mixed picture. Some of these reports were simply discovered through clinical chemistries, others because of clinical symptoms including fulminant hepatitis and death. One case was rechallenged with a positive outcome.

Blood and Lymphatic System: Increased bleeding time

Immune System: lupus erythematosis

Nervous System: Apnea, coma

Renal and Urinary: Hyponatremia/inappropriate ADH secretion, kidney failure

Read the entire FDA prescribing information for Rythmol (Propafenone)

Related Resources for Rythmol
Heart Disease:The No. 1 Killer in the U.S.

Read the Rythmol User Reviews »

© Rythmol Patient Information is supplied by Cerner Multum, Inc. and Rythmol Consumer information is supplied by First Databank, Inc., used under license and subject to their respective copyrights.

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