Viltepso (viltolarsen) is a brand-name intravenous infusion that’s prescribed for Duchenne muscular dystrophy in certain people. As with other drugs, Viltepso can cause side effects, such as injection site reactions or abdominal pain.

Viltepso can cause certain side effects, some of which are more common than others. These side effects may be temporary, lasting a few days to weeks. However, if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

These are just a few of the more common side effects reported by people who took Viltepso in clinical trials:

* For more information about this side effect, see “Side effect specifics” below.

Mild side effects can occur with Viltepso use. This list doesn’t include all possible mild side effects of the drug. For more information, you can refer to Viltepso’s prescribing information.

Mild side effects that have been reported with Viltepso include:

These side effects may be temporary, lasting a few days to weeks. However, if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

Note: After the Food and Drug Administration (FDA) approves* a drug, it tracks and reviews side effects of the medication. If you develop a side effect while taking Viltepso and want to tell the FDA about it, visit MedWatch.

* Viltepso received accelerated approval from the FDA. This means that it was approved based on early results of clinical trials.
† For more information about this side effect, see “Side effect specifics” below.
‡ An allergic reaction is possible after using Viltepso. However, this side effect wasn’t reported in clinical trials. To learn more, see the “Side effect specifics” section below.

Viltepso can cause serious side effects, but they aren’t common. The list below may not include all possible serious side effects of the drug. For more information, you can refer to Viltepso’s prescribing information.

If you develop serious side effects while taking Viltepso, 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.

Serious side effects that have been reported and their symptoms include:

  • Kidney problems.* Symptoms can include:
    • urinating more than usual
    • fatigue
    • blood in your urine
    • increased thirst
  • Decreased ejection fraction (your heart doesn’t pump out blood as well as it should).†
  • Severe allergic reaction.‡

* Kidney problems weren’t reported in Viltepso’s clinical trials but were observed in animal studies of the drug.
† For more information about this side effect, see “Side effect specifics” below.
‡ An allergic reaction is possible after using Viltepso. However, this side effect wasn’t reported in clinical trials. To learn more, see the “Side effect specifics” section below.

Learn more about some of the side effects that Viltepso may cause. To find out how often side effects occurred in clinical trials, see the prescribing information for Viltepso.

Injection site reactions

Viltepso is given as an intravenous infusion by your healthcare professional. Injection site reaction was a common side effect in clinical trials of Viltepso. Symptoms of an injection site reaction around the area where you receive your infusion may include:

  • swelling
  • bruising
  • skin discoloration
  • warmth
  • pain or discomfort

What you can do

Injection site reactions will typically go away on their own. There are some steps you can take to help relieve the symptoms if they bother you. Applying a cold compress may help reduce swelling, itching, and pain. Your doctor may recommend an over-the-counter pain medication such as acetaminophen (Tylenol), which can help reduce pain and inflammation.

Talk with your doctor if your symptoms don’t go away or become severe.

Decreased ejection fraction was commonly reported in clinical trials of Viltepso. Ejection fraction is a measure of how well your heart is functioning. A decreased ejection fraction means your heart isn’t pumping as much blood as it should. Symptoms may include:

  • fatigue
  • feeling full or bloated
  • shortness of breath
  • swelling of ankles and feet
  • loss of appetite
  • increased heart rate

Note that heart problems, including decreased ejection fraction, are common with Duchenne muscular dystrophy. (Viltepso is prescribed to treat this condition.)

What you can do

Contact your doctor if you have new or worsening symptoms of decreased ejection fraction. They may recommend tests to check your heart function. They may also prescribe medication for your heart.

As with most drugs, Viltepso can cause an allergic reaction in some people. However, this side effect wasn’t reported in clinical trials.

Symptoms can be mild or serious and can include:

  • skin rash
  • itching
  • flushing
  • swelling under your skin, typically in your eyelids, lips, hands, or feet
  • swelling of your mouth, tongue, or throat, which can make it hard to breathe

What you can do

For mild symptoms of an allergic reaction, call your doctor right away. They may recommend ways to ease your symptoms and determine whether you should continue using Viltepso. However, if your symptoms are serious and you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Be sure to talk with your doctor about your health history before you receive Viltepso. This drug may not be the right treatment for you if you have certain medical conditions or other factors that affect your health. These include:

Kidney problems.* Viltepso may cause kidney problems. If you already have a kidney condition, such as chronic kidney disease, you may be at a higher risk of kidney problems. Talk with your doctor about receiving Viltepso to determine if it’s the right treatment option for you.

Allergic reaction. If you’ve had an allergic reaction to Viltepso or any of its ingredients, your doctor will likely not prescribe Viltepso. Ask your doctor what other medications may be better options for you.

Pregnancy or breastfeeding. It’s not known if it’s safe to receive Viltepso if you’re pregnant or breastfeeding your child. Viltepso hasn’t been studied in pregnant people or people who are breastfeeding. Please talk with your doctor before receiving Viltepso.

Alcohol consumption. There’s no known interaction between alcohol and Viltepso. If you have questions about alcohol consumption during treatment, talk with your doctor or pharmacist.

* Kidney problems weren’t reported in Viltepso’s clinical trials but were observed in animal studies of the drug.

Viltepso can cause side effects. Most side effects are mild and will typically go away on their own after a few days to weeks. Although not common, Viltepso can cause some serious side effects that may require treatment. Talk with your doctor if you have any side effects that don’t go away, are bothersome, or serious.

If you’d like to learn more about Viltepso, talk with your doctor or pharmacist. They can help answer any questions you have about side effects from taking the drug.

Besides talking with your doctor, you can do some research on your own. These articles might help:

  • More information about Viltepso. For details about other aspects of Viltepso, refer to this article.
  • A look at Duchenne muscular dystrophy (DMD). For details about this condition, see our list of articles related to DMD.

Disclaimer: Medical News Today 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.