Is Amiodarone Safe for AFib?

Atrial fibrillation (AFib) is the most common arrhythmia (abnormal heart beat) diagnosed in the U.S. every year. And about 37 million people have AFib around the world. 

AFib can have serious complications, such as stroke and heart failure. So, it’s important to keep the heart in a normal range and rhythm to minimize risk. Medications like amiodarone (Pacerone) help the heart stay in a normal rhythm. This is especially true in people with underlying heart problems, like heart failure. 

Let’s take a closer look at how amiodarone works and how it can be used safely.

Is amiodarone for AFib a safe option?

In most cases, yes: Amiodarone is safe when you use it correctly. But it does need careful monitoring due to the risk of serious side effects. Amiodarone can cause damage to certain organs and tissues (more on this below). Regular checkups can prevent complications.

The decision to take amiodarone comes down to you and a healthcare professional who knows your medical history. The main question to ask is: Does the benefit of taking amiodarone outweigh the risk of side effects? This all depends on factors like:

• Your specific heart problem

• Other medical issues you may have

• The other medications you may take

• Your access to healthcare

EXPERT PICKS: WHAT TO READ NEXT

• Atrial fibrillation (AFib) is the most common heart rhythm diagnosis in the U.S.: Learn about its causes and triggers so you can minimize your risk. 

• Did you know that AFib increases the risk of stroke? Luckily, blood thinners can help reduce the risk of clotting that leads to stroke. 

• Decoding heart arrhythmias: This guide to arrhythmias explains the types, causes, and treatments for abnormal heart rhythms.

How amiodarone works

Amiodarone works mainly on potassium channels in the electrical system of the heart. When potassium channels are blocked, the electrical conduction system of the heart slows down. This is what makes amiodarone useful for treating the irregular heart rhythm with AFib. 

Amiodarone for AFib: What you should know

Amiodarone is one of the most commonly used medications to treat AFib. But the FDA hasn’t approved it yet for AFib treatment — so prescribers usually reserve it for specific situations. 

Let’s review the two main treatments for AFib.

Medications that control heart rate (rate control)

The most common symptoms of AFib are linked to a fast heart rate, like: 

• Palpitations

• Shortness of breath

• Lightheadedness

In these cases, slowing the heart rate can help. Beta blockers and calcium channel blockers are useful medications for rate control. Healthcare professionals sometimes use amiodarone for rate control. But it isn’t as fast and effective as beta blockers and calcium channel blockers.

Medications that keep the heart in normal rhythm (rhythm control)

If the medications mentioned above aren’t working well, or you still have symptoms, then rhythm control medications can be useful. Rhythm control medications convert the heart from AFib back into a normal rhythm — and keep it there. 

Amiodarone is an example of a rhythm control medication. Others include: 

• Flecainide

• Propafenone

• Dofetilide

• Sotalol

How well does amiodarone work compared to other medications for AFib?

Amiodarone is the most effective AFib medication when the goal is to restore and keep the heart in its normal rhythm. That’s the position of leading heart organizations like the American Heart Association and American College of Cardiology. Researchers have extensively tested amiodarone against rhythm control medications like sotalol, flecainide, and propafenone. 

Studies show that amiodarone works better to keep AFib away. In one study, 65% of people taking amiodarone maintained their normal heart rhythms. That’s compared to about 40% of those taking other rhythm control medications. 

What is the dosage of amiodarone for AFib?

The dose of amiodarone that’s right for you depends on your medical history and heart problems. 

If a healthcare professional prescribes you amiodarone outside of a hospital, you’ll likely take a higher dose for a few weeks so that it can build up in your system. Then you’ll take a lower maintenance dose every day, typically between 100 mg and 200 mg. 

Remember: Amiodarone doses can vary from person to person. So be sure to check with your prescriber’s office or pharmacist if you have questions.

Why is amiodarone a high-risk medication?

Rhythm control medications work well to keep the heart in a normal rhythm. But the tradeoff is the risk of increased side effects. And when it comes to side effects and toxicity, amiodarone has one of the worst track records. 

The good news is that there’s a lot of research on how to safely use amiodarone. We’ll summarize the main points here.

Who experiences side effects

Side effects from amiodarone happen quite often. In the first year, 15% of people experience them. With long-term use, they affect half of people. 

But compared to other rhythm control medications, amiodarone is associated with fewer cardiac emergencies, such as arrhythmia and sudden cardiac arrest. So, for many people, the tradeoff is worthwhile — especially since there are ways to prescribe and take amiodarone safely (more on this below). 

Most common side effect

Nearly everyone who takes amiodarone gets microdeposits on the cornea of the eye. For most people, this doesn’t cause any problems. But some people can develop halo vision and light sensitivity.

Other risks

There are other important risks to consider as well. Research shows that people who took amiodarone had significantly higher rates of serious damage to these organs:

• Thyroid (overactive or underactive thyroid disease)

• Liver (elevated liver enzymes and jaundice) 

• Lung (lung scarring and other serious lung conditions) 

• Heart (heart conduction system abnormalities and dangerously low heart rates)

• Neurological system (peripheral neuropathy and cognitive impairment)

• Skin (blue skin discoloration and sensitivity to the sun)

Pregnancy

Pregnant people should also avoid amiodarone, as it can lead to thyroid and neurological issues in the developing pregnancy.

What makes amiodarone more toxic than other medications?

Amiodarone can become toxic. That’s because it can easily enter various tissues of the body, like fat and muscle. And it can enter organs, like the liver and lung. Amiodarone and its main byproduct, desethylamiodarone, can then accumulate in these tissues. And it can remain in the body for several months. This can happen even after you stop the medication.

Researchers don’t know exactly how amiodarone causes damage. And the damage may differ from one organ to the next. In the lung, for example, amiodarone may cause the immune system to attack lung tissue. It can also cause direct damage to lung cells. Also, amiodarone contains iodine and has many structural similarities to thyroid hormones. So, it can cause both overactive and underactive thyroid conditions.

Side effects of amiodarone

Amiodarone side effects can range from being a minor nuisance to a serious threat that leads to permanent organ damage. Mild side effects can occur within a few days to weeks, including:

• Fatigue

• Tremor 

• Nausea

• Constipation

• Headache

• Loss of appetite 

Mild side effects from amiodarone may settle over time and not be a cause for concern. But if symptoms persist, it may be a sign of something more serious, such as one or more of the organ toxicities discussed above. 

If you have questions or concerns about side effects, especially if you’ve recently started amiodarone, reach out to your prescriber. 

Does amiodarone interact with other medications?

Yes — amiodarone interacts with several medications. Some common examples are:

• Warfarin

• Digoxin

• Procainamide

• Some calcium channel blockers

• Some beta blockers

• Phenytoin

• Cyclosporine

• Statins 

Here’s a complete list of amiodarone interactions. 

Medication interactions with amiodarone can cause serious complications, like slow heart rates, decreased blood pressure, and increased medication levels. That’s why it’s important to go over your full medication list with your prescriber and the pharmacist who fills your prescriptions. 

How to stay safe when taking amiodarone

It’s possible to stay safe when taking amiodarone. People have been taking amiodarone for decades, so there’s a lot of shared experience to draw from. 

Here’s how to make sure you stay safe and healthy when taking amiodarone:

• Take the lowest effective dose. Studies show that low-dose (200 mg daily or less) and very low-dose (100 mg daily or less) amiodarone cause less toxicity than higher doses of amiodarone. If you’re taking over 200 mg daily, check with your prescriber to confirm that’s the lowest dose needed to treat your AFib.

• Take it for the shortest time necessary. Sometimes, people need amiodarone for a period of weeks or months, like after heart surgery. Check with your healthcare team to find out how long you’ll need to take amiodarone. 

• Monitor your thyroid, liver, and lungs. You need thyroid and liver blood tests before you start amiodarone and every 6 months while you take it. You also need lung function tests and chest X-rays before and during amiodarone use.

• Check in frequently with your healthcare team. Stay in close contact with your primary care provider and cardiologist so they can monitor your electrocardiogram (ECG or EKG) and check you for side effects.

• Visit your pharmacist. You should go over your medication list because amiodarone has many medication interactions.

Your prescriber may need to adjust your amiodarone dose, depending on how your heart tolerates the medication and if you have any side effects.

Alternatives to amiodarone for AFib

If you can’t tolerate amiodarone, or if you have a medical condition that doesn’t allow you to take it, there are several other options for AFib treatment.

Dronedarone

Dronedarone is a medication that’s very similar to amiodarone, but it doesn’t contain iodine. As a result, dronedarone isn’t associated with most of the non-cardiac side effects of amiodarone. But it’s not as effective as amiodarone for decreasing AFib. And its use is linked to higher death rates in people with heart failure.

Rate or rhythm control medications

Rate control medications, such as beta blockers and calcium channel blockers, are common in the treatment of AFib. Rhythm control medications, such as dofetilide, are also common, especially in people who have heart failure. 

Remember never to stop a heart medication — including amiodarone — until you discuss your concerns with your healthcare team.

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Written by:

Alice Perlowski, MD, MA, FACC

Dr. Alice Perlowski is a board-certified cardiologist and fellow of the American College of Cardiology. She has seen patients and supervised trainees in the academic and private sector, with focuses in interventional cardiology, vascular medicine, preventative cardiology, and women’s heart health.

Edited by:

Karla Robinson, MD

Karla Robinson, MD, is a medical editor for GoodRx. She is a licensed, board-certified family physician with almost 20 years of experience in health through varied clinical, administrative, and educational roles.

Reviewed by:

Frank Schwalbe, MD

Frank Schwalbe, MD, is an assistant professor of anesthesiology at the Yale School of Medicine. He has practiced anesthesiology for 30 years.

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