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Rythmol Side Effects

Generic name: propafenone

Medically reviewed by Last updated on Mar 15, 2024.

Note: This document contains side effect information about propafenone. Some dosage forms listed on this page may not apply to the brand name Rythmol.

Applies to propafenone: oral capsule extended release, oral tablet.


Oral route (Tablet; Capsule, Extended Release)

It is prudent to consider any Class 1C antiarrhythmic to have a significant proarrhythmic risk in patients with structural heart disease. Given the lack of any evidence that these drugs improve survival, antiarrhythmic agents should generally be avoided in patients with non-life-threatening ventricular arrhythmias, even if the patients are experiencing unpleasant, but not life-threatening, symptoms or signs.

Serious side effects of Rythmol

Along with its needed effects, propafenone (the active ingredient contained in Rythmol) may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking propafenone:

Less common


Other side effects of Rythmol

Some side effects of propafenone may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

Less common

For Healthcare Professionals

Applies to propafenone: oral capsule extended release, oral tablet.


Adverse reactions occurred most commonly in the cardiovascular, gastrointestinal, and nervous systems.[Ref]


Common (1% to 10%): Palpitation, angina pectoris, atrial flutter, first-degree atrioventricular block, bradycardia, congestive heart failure, cardiac murmur, left bundle branch block, right bundle branch block, conduction disorders, sinus bradycardia, hypotension, wide complex tachycardia, ventricular tachycardia or ventricular fibrillation, recurrent supraventricular tachycardia

Uncommon (0.1% to 1%): Premature ventricular contractions increased

Frequency not reported: PR interval prolongation, QRS interval prolongation, unstable angina, atrial hypertrophy, cardiac arrest, coronary artery disease, extrasystoles, myocardial infarction, nodal arrhythmia, pericarditis, sinoatrial block, sinus arrest, sinus arrhythmia, supraventricular extrasystoles, ventricular extrasystoles, ventricular hypertrophy, abnormal heart sounds, abnormal pulse, carotid bruit, blood pressure decreased, blood pressure increased, limb arterial embolism, deep limb venous thrombosis, flushing, hematoma, hypertension, hypertensive crisis, labile blood pressure, pallor, peripheral coldness, peripheral vascular disease, thrombosis, intraventricular conduction delay, second-degree atrioventricular block, atrioventricular dissociation, hot flashes, sick sinus syndrome, sinus pause or arrest, supraventricular tachycardia, torsade de pointes, asystole[Ref]


Very common (10% or more): Nausea and/or vomiting (11%)

Common (1% to 10%): Constipation, diarrhea, dry mouth, flatulence

Frequency not reported: Abdominal distention, abdominal pain, duodenitis, dyspepsia, dysphagia, eructation, gastritis, gastroesophageal reflux disease, gingival bleeding, glossitis, glossodynia, gum pain, halitosis, intestinal obstruction, melena, mouth ulceration, pancreatitis, peptic ulcer, rectal bleeding, gastroenteritis[Ref]

Nervous system

Very common (10% or more): Unusual taste (up to 14%)

Common (1% to 10%): Dizziness, headache, tremor, somnolence, ataxia

Uncommon (0.1% to 1%): Seizures

Frequency not reported: Tinnitus, vertigo, sciatica, amnesia, balance impaired, brain damage, cerebrovascular accident, dementia, gait abnormal, hypertonia, hypoesthesia, paralysis, paresthesia, peripheral neuropathy, speech disorder, syncope, tongue hypoesthesia, memory loss, numbness, unusual smell sensation, myasthenia gravis exacerbated

Postmarketing reports: Coma[Ref]


Common (1% to 10%): Dyspnea, upper respiratory tract infection, rales, wheezing

Frequency not reported: Sore throat, atelectasis, breath sounds decreased, chronic obstructive airways disease, cough, epistaxis, hemoptysis, lung disorder, pleural effusion, pulmonary congestion, respiratory failure, rhinitis, throat tightness

Postmarketing reports: Apnea[Ref]


Common (1% to 10%): Chest pain, fatigue, edema, weakness

Frequency not reported: Hearing impaired, feeling hot, malaise, pain, pyrexia, breast pain, death[Ref]


Common (1% to 10%): Ecchymosis

Frequency not reported: Alopecia, dermatitis, dry skin, erythema, nail abnormality, petechiae, pruritus, sweating increased, urticaria, rash, purpura[Ref]


Common (1% to 10%): Hematuria

Frequency not reported: Glycosuria present, prostatic specific antigen increased, ketonuria present, proteinuria present, dysuria, nocturia, oliguria, pyuria, urinary casts, urinary frequency, urinary incontinence, urinary retention, urine abnormal, impotence, prostatism, sperm count decreased[Ref]


Common (1% to 10%): Blood alkaline phosphatase increased

Frequency not reported: Hepatomegaly, ALT increased, AST increased, blood bilirubin increased, gamma-glutamyltransferase increased, cholestasis, hepatitis

Postmarketing reports: Liver abnormalities[Ref]


Common (1% to 10%): Influenza

Uncommon (0.1% to 1%): Positive antinuclear antibody titer[Ref]


Common (1% to 10%): Anorexia

Frequency not reported: Weight decreased, blood cholesterol increased, blood glucose increased, blood triglycerides increased, blood uric acid increased, weight increased, dehydration, diabetes mellitus, gout, hypercholesterolemia, hyperglycemia, hyperlipidemia, hypokalemia

Postmarketing reports: Hyponatremia/inappropriate antidiuretic hormone secretion[Ref]


Common (1% to 10%): Blurred vision

Frequency not reported: Eye hemorrhage, eye inflammation, eyelid ptosis, miosis, retinal disorder, visual acuity reduced, vision abnormal, eye irritation[Ref]


Common (1% to 10%): Anxiety, depression

Frequency not reported: Insomnia, libido decreased, emotional disturbance, mental disorder, neurosis, nightmare, sleep disorder, abnormal dreams, confusion, psychosis/mania[Ref]


Frequency not reported: Blood prolactin increased[Ref]


Frequency not reported: Anemia, lymphadenopathy, spleen disorder, thrombocytopenia, hemorrhage, blood chloride decreased, blood sodium decreased, hemoglobin decreased, neutrophil count decreased, platelet count decreased, prothrombin level decreased, red blood cell count decreased, blood lactate dehydrogenase increased, eosinophil count increased, monocyte count increased, prothrombin level increased, white blood cell count increased, granulocytopenia, leukopenia

Postmarketing reports: Bleeding time increased[Ref]


Frequency not reported: Blood creatinine increased, blood urea increased, renal failure, nephrotic syndrome

Postmarketing reports: Kidney failure[Ref]


Common (1% to 10%): Muscle weakness

Frequency not reported: Arthritis, bursitis, collagen-vascular disease, costochondritis, joint disorder, muscle cramps, muscle spasm, myalgia, neck pain, jaw pain, tendonitis

Postmarketing reports: Lupus erythematosus[Ref]


1. "Product Information. Rythmol (propafenone)." Knoll Pharmaceutical Company

2. (2011) "Product Information. Rythmol SR (propafenone)." GlaxoSmithKline

Further information

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

Some side effects may not be reported. You may report them to the FDA.