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Flecainide

Brand names: Tambocor (brand discontinued)

Flecainide helps prevent atrial fibrillation and SVT episodes in people without structural heart disease.

Brand namesTambocor (brand discontinued)
Type of medicineAntiarrhythmic (heart rhythm medicine)
Prescription?Prescription
ImportantThis page is general information, not a prescription. Don't start, stop, or change a medicine without talking to your provider or pharmacist.

Overview

Some people use it as a 'pill in the pocket' at the start of an AFib episode, as their provider directs.

What it's used for

  • Preventing atrial fibrillation and flutter
  • Preventing SVT

How to take it

  • Take it at the same times each day.
  • Usually taken with a heart-rate medicine such as a beta blocker.

Your dose depends on your health and other medicines. Always follow your prescription label, and ask your pharmacist if anything is unclear.

Side effects

Common side effects

  • Dizziness
  • Blurry vision
  • Headache
  • Nausea
Call 911Fainting, chest pain, or a very fast or irregular heartbeat
Call your provider todayShortness of breath or swelling

Warnings

  • Boxed warning: not for people who've had a heart attack or have heart failure; it raised death rates in those groups.

Other medicines, foods, and alcohol

  • Amiodarone and some antidepressants raise its level.
  • Other medicines that affect heart rhythm add to risk.

Tell your provider and pharmacist about every medicine, vitamin, and supplement you take.

Pregnancy and breastfeeding

Talk with your provider.

Missed doses, overdose, and storage

If you miss a dose

Take it as soon as you remember, unless it's almost time for your next dose. Then skip the missed dose. Don't take two doses at once.

If someone takes too much

Call Poison Control at 1-800-222-1222 or get help online at poison.org. Call 911 if the person collapses, has a seizure, has trouble breathing, or can't be woken.

Storing it

Store at room temperature, away from heat and moisture (not in the bathroom), and out of reach of children and pets.

Conditions it's used for

Sources

Last updated 2026-11-13.