Multaq (dronedarone) is a prescription drug used to reduce the risk of hospitalization in certain adults with atrial fibrillation (AFib). Multaq can cause side effects that range from mild to serious. Examples include diarrhea, nausea, and vomiting.

Specifically, Multaq can be prescribed for people with a regular sinus rhythm (heart rhythm) but with a history of paroxysmal AFib or persistent AFib.

The active ingredient in Multaq is dronedarone. (An active ingredient is what makes a drug work.) The drug comes as an oral tablet.

Keep reading to learn about the common, mild, and serious side effects that Multaq can cause. For a general overview of the drug, including details about its uses, see this article.

Some people may experience mild to serious side effects during Multaq treatment. Examples of the drug’s commonly reported side effects include:

  • diarrhea*
  • nausea
  • vomiting
  • skin rash or itchiness
  • feeling weak

* To learn more about this side effect, see the “Side effects explained” section below.

Mild side effects have been reported with Multaq. These include:

In most cases, these side effects should be temporary. And some may be easily managed. But if you have symptoms that are ongoing or bothersome, talk with your doctor or pharmacist. And do not stop taking Multaq unless your doctor recommends it.

Multaq may cause mild side effects other than those listed above. See the drug’s prescribing information for details.

* To learn more about this side effect, see the “Side effects explained” section below.
† An allergic reaction is possible after taking Multaq, but it’s not clear whether this side effect occurred in studies.

Serious side effects have been reported with Multaq. These include:

If you develop serious side effects while taking Multaq, call your doctor right away. If the side effects seem life threatening or you think you’re having a medical emergency, immediately call 911 or your local emergency number.

* To learn more about this side effect, see the “Side effects explained” section below.
† An allergic reaction is possible after taking Multaq, but it’s not clear whether this side effect occurred in studies.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks and reviews side effects of the medication. If you’d like to notify the FDA about a side effect you’ve had with Multaq, visit MedWatch.

Get answers to some frequently asked questions about Multaq’s side effects.

Can Multaq cause weight gain or hair loss?

No, you shouldn’t experience weight gain or hair loss from taking Multaq. These side effects weren’t reported in studies of people taking this medication.

However, weight gain may be a symptom of heart failure. And, since Multaq can cause new or worsening heart failure, it’s important that you tell your doctor about any weight gain you experience. They can help determine what may be causing the weight gain and recommend ways to help manage it.

In addition, Multaq isn’t known to cause hair loss, but other medications prescribed to treat atrial fibrillation can. An example of this is Jantoven (warfarin). If you experience hair loss during your treatment with Multaq, talk with your doctor. They can help determine what may be causing it.

Does Multaq cause long-term side effects?

It’s possible. Long-term side effects include those that may start at any time you’re taking a drug even if you’ve taken it for a long time. It also includes side effects that may not go away, even after you stop taking the drug.

Examples of long-term side effects reported in Multaq’s studies include:

Talk with your doctor to learn more about possible side effects of Multaq and how long they may last.

Learn more about some of the side effects Multaq may cause.

Increased risks of death, stroke, and heart failure in certain people

Multaq has a boxed warning for the increased risks of death, stroke, and heart failure in certain people with:

  • permanent atrial fibrillation (AFib)
  • heart failure that’s severe, recently worsened, or recently needed treatment in a hospital

A boxed warning is the most serious warning from the Food and Drug Administration (FDA). It alerts doctors and patients about drug effects that may be dangerous.

Be sure to tell your doctor about any symptoms of heart failure that you experience during Multaq treatment. These may include:

You should also be sure to tell your doctor if you have an irregular pulse during your treatment with Multaq. Symptoms may include fatigue (low energy), dizziness, or sweating.

What might help

Due to the risks of death, stroke, and heart failure, Multaq isn’t recommended for certain people. This includes those with severe heart failure, recent hospitalization for heart failure, and permanent AFib.

Talk with your doctor about any heart conditions you have before starting Multaq. They can help determine whether this medication would be safe for you.

Diarrhea

Diarrhea was a common side effect reported in studies of Multaq. Diarrhea may cause symptoms such as:

  • loose, watery stools
  • abdominal pain
  • upset stomach
  • urgent need to use the bathroom

What might help

If you have diarrhea during Multaq treatment, consider an over-the-counter treatment option such as Imodium (loperamide). You should also talk with your doctor. They’ll likely recommend drinking plenty of fluids to help avoid dehydration (low fluid level).

Allergic reaction

Like most drugs, Multaq can cause an allergic reaction in some people. But it’s not clear whether this side effect occurred in studies. Symptoms can be mild to serious and can include:

  • skin rash
  • itchiness
  • flushing (temporary warmth, redness, or deepening of skin color)
  • swelling under your skin (usually in your eyelids, lips, hands, or feet)
  • swelling of your mouth, tongue, or throat, which can make it hard to breathe

What might help

If you have mild symptoms of an allergic reaction, such as a mild rash, call your doctor right away. They may suggest a treatment to manage your symptoms. Examples include:

  • an oral antihistamine, such as Benadryl (diphenhydramine)
  • a product you apply to your skin, such as hydrocortisone cream

If your doctor confirms you’ve had a mild allergic reaction to Multaq, they’ll decide whether you should continue taking it.

If you have symptoms of a severe allergic reaction, such as swelling or trouble breathing, call 911 or your local emergency number right away. These symptoms could be life threatening and require immediate medical care.

If your doctor confirms you’ve had a serious allergic reaction to Multaq, they may have you switch to a different treatment.

Keeping track of side effects

During your Multaq treatment, consider taking notes on any side effects you’re having. You can then share this information with your doctor. This is especially helpful when you first start taking a new drug or using a combination of treatments.

Your side effect notes can include things such as:

  • what dose of the drug you were taking when you had the side effect
  • how soon you had the side effect after starting that dose
  • what your symptoms were
  • how your symptoms affected your daily activities
  • what other medications you were taking
  • any other information you feel is important

Keeping notes and sharing them with your doctor will help them learn more about how Multaq affects you. They can then use this information to adjust your treatment plan if needed.

Below is important information you should consider before starting Multaq.

Boxed warning: Increased risks of death, stroke, and heart failure in certain people

Multaq has a boxed warning for the increased risks of death, stroke, and heart failure in certain people. A boxed warning is the most serious warning from the Food and Drug Administration (FDA).

Multaq may increase the risks of death, stroke, and heart failure in certain people with:

  • permanent atrial fibrillation (AFib)
  • heart failure that’s severe, recently worsened, or recently needed treatment in a hospital

To learn more, see the “Side effects explained” section above.

Other warnings

Multaq can sometimes cause harmful effects in people with certain conditions. This is known as a drug-condition interaction. Other factors may also affect whether Multaq is a good treatment option for you.

Talk with your doctor about your health history before starting this medication. Be sure to tell them if any of the following factors apply to you:

  • heart block
  • permanent AFib
  • heart failure (certain situations)
  • sick sinus syndrome
  • taking certain medications or supplements that interact with Multaq
  • taking certain medications or supplements that increase the risk of long QT syndrome
  • liver or lung problems from taking a medication called amiodarone
  • severe liver problems
  • heart rhythm problems, such as long QT syndrome
  • heart rate below 50 beats per minute
  • past allergic reaction to Multaq
  • pregnancy
  • breastfeeding

Alcohol and Multaq

There are no known interactions between alcohol and Multaq. However, it’s possible to develop liver problems from drinking alcohol. And, since Multaq can also cause liver problems, drinking alcohol may increase this risk further.

If you have questions about consuming alcohol while taking Multaq, talk with your doctor or pharmacist.

Pregnancy and breastfeeding with Multaq

Before starting Multaq treatment, it’s important to talk with your doctor if you’re pregnant, breastfeeding, or planning to be either.

Pregnancy

Multaq may cause harm to a developing fetus and is not safe to take during pregnancy.

If you’re able to become pregnant, your doctor may recommend using a form of birth control during your Multaq treatment. If you have questions about the best form of contraception to use while you’re taking Multaq, ask your doctor.

If you’re pregnant or planning to become pregnant, talk with your doctor about your treatment options.

Breastfeeding

It isn’t known whether Multaq is safe to take while breastfeeding. However, because of the possible risks, Multaq is not recommended for those who are breastfeeding.

If you’re breastfeeding or planning to do so, talk with your doctor before starting this medication.

Like most drugs, Multaq can cause a number of side effects that range from mild to serious. But most are temporary and go away after a few days to weeks. If you have questions about side effects this drug can cause, talk with your doctor. Examples of questions to help get you started include:

  • Can you adjust my dose if I have side effects from Multaq?
  • How can I manage side effects that I experience with this medication?
  • Do any of the other drugs or supplements I take increase my risk of side effects from Multaq?

To learn more about Multaq, see these articles:

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Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.