flecainide acetate at a glance
Medicine class
Class IC anti-arrhythmic and cardiac sodium-channel blocker
Main role
Control of selected serious abnormal heart rhythms
Specialist oversight
Starting or changing treatment generally requires specialist supervision and ECG monitoring
Food
Selected products should be taken on an empty stomach or at least one hour before food
What is flecainide acetate used for?
Licensed indications differ slightly between products.
AV nodal reciprocating tachycardia and rhythm disorders associated with Wolff–Parkinson–White syndrome or similar accessory pathways.
Selected paroxysmal atrial arrhythmias with disabling symptoms.
Selected serious symptomatic ventricular arrhythmias, particularly when other treatments are ineffective or not tolerated.
Maintenance of normal rhythm after conversion, where specified by the product licence.
Specialist use outside the adult product licence to treat an abnormally fast fetal heartbeat.
How does flecainide acetate work?
It blocks fast sodium channels in heart cells, slowing conduction and helping interrupt or prevent abnormal electrical circuits. It can lengthen the PR interval and widen the QRS complex on an ECG.
flecainide acetate preparations and strengths
Oral solution
Route: Oral
Strengths: 25 mg/5 mL, 50 mg/5 mL
Tablet
Route: Oral
Strengths: 50 mg, 100 mg
How to take flecainide acetate
Take it exactly as prescribed and do not stop without discussing this with the prescriber. Follow the instructions for the specific product.
Swallow tablets with water.
Take selected products on an empty stomach or at least one hour before food.
Measure oral solution with the supplied cup or oral syringe, not a household spoon.
Some liquids can temporarily numb the mouth; avoid eating until sensation returns.
Do not switch between tablets or liquids without professional advice.
flecainide acetate side effects
Common or expected effects
- Dizziness, light-headedness or vertigo
- Blurred or double vision
- Weakness or tiredness
- Breathlessness
- Fluid retention or swelling
- New or worsening abnormal heart rhythm
Get urgent medical advice
- New, markedly faster, slower or irregular heartbeat
- Fainting, chest pain, severe breathlessness or signs of heart failure
- Heart block or cardiac arrest
- Convulsions
- Persistent cough or breathlessness from lung inflammation or scarring
- Jaundice or other signs of liver dysfunction
- Serious hives or swelling of the lips, tongue or mouth
flecainide acetate in pregnancy
Flecainide crosses the placenta, and pregnancy safety data are limited. A specialist may use it for a potentially serious maternal or fetal rhythm disorder, with closer monitoring where needed. Do not stop established treatment without specialist advice.
flecainide acetate while breastfeeding
Flecainide passes into breast milk. Product information advises use only when expected benefit outweighs potential risk, so specialist assessment is important, particularly for a premature or unwell infant. Evidence about infant exposure is limited.
flecainide acetate interactions
Flecainide has a narrow therapeutic range. Medicines affecting cardiac conduction, electrolytes or CYP2D6 can alter its safety or effectiveness.
Other class I anti-arrhythmics
Combined sodium-channel blockade can cause dangerous additive cardiac effects and is contraindicated for selected products.
Amiodarone
Can increase flecainide exposure and cardiac effects.
Common questions about flecainide acetate
Answers are fully visible for fast scanning and source review.
Can flecainide acetate make an arrhythmia worse?
Yes. It can worsen an existing rhythm disorder or cause a new one, which is why specialist selection and ECG monitoring matter.
Why are ECGs needed?
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.