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Heart Disease Health Center

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Antiarrhythmics for Congenital Heart Defects


Generic Name Brand Name
phenytoin Dilantin, Phenytek
propranolol Inderal, Innopran

How It Works

Antiarrhythmic medicines act on the electrical system of the heart. They block some of the extra electrical activity in the cells of the heart. This makes the heart beat regularly.

Why It Is Used

Antiarrhythmic medicines are used to treat and prevent irregular heartbeats.

How Well It Works

Antiarrhythmic medicines help control irregular heartbeats. They do not treat the congenital heart defect itself.

Side Effects

Antiarrhythmic medicine side effects are specific to each type of medicine. Your child's doctor will check your child closely for serious side effects such as an abnormal heart rate problem.

Ask your child's doctor or pharmacist about the side effects of your child's medicine. Side effects are also listed in the information that comes with the medicine.

Here are some important things to think about:

  • Usually the benefits of the medicine are more important than any minor side effects.
  • Side effects may go away after your child takes the medicine for a while.
  • If side effects still bother your child and you wonder if he or she should keep taking the medicine, call your doctor. He or she may be able to lower the dose or change the medicine. Do not suddenly have your child quit taking the medicine unless your doctor says to.

Call911or other emergency services right away if your child has:

Call your doctor if your child has:

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

What To Think About

Do not stop giving antiarrhythmic medicine without the advice of your child's doctor. It is dangerous to stop some of these medicines suddenly.

Antiarrhythmic medicines might interact with many other medicines that your child might take. Tell your child's doctor all of the medicines that your child takes. Be sure to include nonprescription medicines, vitamins, and supplements.

Taking medicine

Know how to give your child's medicine safely. For help, see the topic Congenital Heart Defects: Caring for Your Child.

Medicine is one of the many tools your doctor has to treat a health problem. If your child takes medicine as your doctor suggests, it will improve your child's health and may prevent future problems. If your child doesn't take the medicines properly, his or her health (and perhaps life) may be at risk.

There are many reasons why people have trouble taking their medicine. But in most cases, there is something you can do. For suggestions on how to work around common problems, see the topic Taking Medicines as Prescribed.


Follow-up care is a key part of your child's treatment and safety. Be sure to make and go to all appointments, and call your doctor if your child is having problems. It's also a good idea to know your child's test results and keep a list of the medicines your child takes.

Complete the new medication information form (PDF)(What is a PDF document?) to help you understand this medication.

ByHealthwise Staff
Primary Medical ReviewerJohn Pope, MD - Pediatrics
Specialist Medical ReviewerLarry A. Latson, MD - Pediatric Cardiology

Current as ofMarch 12, 2014

WebMD Medical Reference from Healthwise

Last Updated: March 12, 2014
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

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