adenosine vs flecainide
Side-by-side comparison of adenosine and flecainide Data from FDA drug databases (Orange Book, NDC Directory, recalls, shortages) covering 20,000+ approved drugs, plus CMS pricing; see our methodology.
Adenocard
Tambocor
Adenosine (Adenocard) is a medicine used to treat certain types of irregular heartbeats. It belongs to a class of drugs called antiarrhythmics.
Flecainide is a medicine used to prevent irregular heartbeats. It helps your heart beat normally.
Adenosine is used to treat a very fast heart rate in the upper chambers of your heart. This condition is called supraventricular tachycardia (SVT). Adenosine helps to slow down your heart rate to a normal rhythm.
This medicine can prevent fast heart rates in the upper chambers of the heart. This includes supraventricular tachycardia and atrial fibrillation/flutter. Flecainide can also prevent life-threatening fast heartbeats in the lower chambers (ventricles). It is usually started in the hospital for these serious ventricular problems.
Adenosine works by slowing down the electrical signals in your heart. This helps to interrupt the fast heart rhythm and restore a normal heartbeat. It does this by acting on specific receptors in the heart tissue.
Flecainide works by slowing down electrical signals in the heart. This helps to stabilize your heart rhythm. It belongs to a class of drugs called Class IC antiarrhythmics.
No common side effects listed.
- • Dizziness
- • Vision problems
- • Difficulty breathing
- • Headache
- • Nausea
- The medicine did not work 327
- Using the medicine for a condition it is not approved for 98
- Very fast heart rate 94
- Low blood pressure 86
- Heart stops beating 78
- Irregular heartbeat in the upper chambers 337
- Feeling tired 276
- Difficulty breathing 270
- Feeling lightheaded 255
- Feeling sick to your stomach 244
Since this medication is administered by a healthcare provider in a monitored setting, there are no specific at-home warnings.
Flecainide can increase the risk of death or cardiac arrest in some patients who have had a heart attack. It is generally not recommended for people with less serious, but unpleasant, heart rhythm problems. Flecainide is also not recommended if you have chronic atrial fibrillation.
It is not known if adenosine can harm an unborn baby. Talk to your doctor if you are pregnant or plan to become pregnant. It is also not known if adenosine passes into breast milk, so discuss this with your doctor if you are breastfeeding.
Tell your doctor if you are pregnant or plan to become pregnant. It is not known if flecainide can harm an unborn baby. Talk to your doctor about the risks and benefits of taking flecainide while breastfeeding.
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How to Read This adenosine vs flecainide Comparison
adenosine is classified in the Endogenous Nucleoside (Antiarrhythmic) drug class, while flecainide sits within the Class IC Antiarrhythmic class. Drugs from different classes work through distinct mechanisms, so a head-to-head comparison illustrates trade-offs rather than equivalence. Both drugs are prescription-only, so a licensed provider must authorize use.
Adverse event totals above are pulled from the FDA's Adverse Event Reporting System (FAERS). For these top-ranked reactions alone, adenosine has 683 submissions while flecainide has 1,382. Those figures reflect cumulative reporting volume — not per-patient risk — so older, widely dispensed drugs typically look worse on count alone. No direct interaction between these two drugs is listed in our FDA-derived dataset, though co-prescription still warrants pharmacist review. Serious warnings, pregnancy guidance, and contraindications can differ even when indications overlap.
A table cannot substitute for clinical judgment. Effectiveness, tolerability, drug-drug interactions with your other medications, kidney and liver function, pregnancy status, insurance formulary, and price all feed into a decision that only a licensed prescriber can make responsibly. Data here is sourced from FDA Structured Product Labels (SPL) and FAERS, both of which update as manufacturers and clinicians submit new information. This page is for educational purposes only, is not medical advice, and should not be used to self-switch between adenosine and flecainide — always consult your physician or pharmacist first.
Important: This comparison is for informational purposes only. Drug effects vary between individuals. Always consult your doctor or pharmacist for personalized medical advice.