Tambocor treats abnormal or irregular heartbeats. It may cause dizziness or blurred vision.

Tambocor Overview


Tambocor is a prescription medication used to prevent certain types of life-threatening irregular heartbeats. This medication belongs to a group of drugs called Class I antiarrhythmics which work by blocking sodium channels in the heart, slowing down electrical signals to stabilize heart rhythm.

Tambocor comes in tablet form. It is usually taken once every 8 or 12 hours, with or without food.

Common side effects include headache, weakness, changes in vision, and dizziness. Do not drive or operate heavy machinery until you know how it affects you.

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  • Other
  • Arrhythmias, Cardiac
  • Tachycardia, Ventricular

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Uses of Tambocor

Tambocor is a prescription medication used to prevent certain types of arrhythmias (irregular heartbeats) including:

  • paroxysmal supraventricular tachycardia (PSVT)
  • paroxysmal atrial fibrillation or atrial flutter (PAF)
  • life-threatening ventricular arrhythmia

This medication may be prescribed for other uses. Ask your doctor or pharmacist for more information.



For more information on this medication choose from the list of selections below.

Tambocor Drug Class

Tambocor is part of the drug class:

Side Effects of Tambocor

Common side effects include:

  • dizziness
  • changes in vision
  • shortness of breath
  • headache
  • nausea
  • fatigue
  • weakness

This is not a complete list of Tambocor side effects. Ask your doctor or pharmacist for more information.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.


Tambocor FDA Warning


Mortality. Tambocor was included in the National Heart Lung and Blood Institute's Cardiac Arrhythmia Suppression Trial (CAST), a longterm, multicenter, randomized, double-blind study in patients with asymptomatic non-life-threatening ventricular arrhythmias who had a myocardial infarction more than six days but less than two years previously. An excessive mortality or non-fatal cardiac arrest rate was seen in patients treated with Tambocor compared with that seen in patients assigned to a carefully matched placebo-treated group. This rate was 16/315 (5.1%) for Tambocor and 7/309 (2.3%) for the matched placebo. The average duration of treatment with Tambocor in this study was ten months.

The applicability of the CAST results to other populations (e.g., those without recent myocardial infarction) is uncertain, but at present, it is prudent to consider the risks of Class IC agents (including Tambocor ), coupled with the lack of any evidence of improved survival, generally unacceptable in patients without life-threatening ventricular arrhythmias, even if the patients are experiencing unpleasant, but not life-threatening, symptoms or signs.

Ventricular Pro-arrhythmic Effects in Patients with Atrial Fibrillation/Flutter. A review of the world literature revealed reports of 568 patients treated with oral Tambocor for paroxysmal atrial fibrillation/flutter (PAF). Ventricular tachycardia was experienced in 0.4% (2/568) of these patients. Of 19 patients in the literature with chronic atrial fibrillation (CAF), 10.5% (2) experienced VT or VF. Tambocor IS NOT RECOMMENDED FOR USE IN PATIENTS WITH CHRONIC ATRIAL FIBRILLATION. Case reports of ventricular proarrhythmic effects in patients treated with Tambocor for atrial fibrillation/flutter have included increased PVCs, VT, ventricular fibrillation (VF), and death.

As with other Class I agents, patients treated with Tambocor for atrial flutter have been reported with 1:1 atrioventricular conduction due to slowing the atrial rate. A paradoxical increase in the ventricular rate also may occur in patients with atrial fibrillation who receive Tambocor. Concomitant negative chronotropic therapy such as digoxin or beta-blockers may lower the risk of this complication.