Beyfortus (nirsevimab-alip) is a prescription drug used to help prevent serious illness from respiratory syncytial virus (RSV) in certain children. Beyfortus can cause side effects that range from mild to serious. Examples include rash and injection site reactions.
The active ingredient in Beyfortus is nirsevimab-alip. The drug is a
Keep reading to learn about common, mild, and serious side effects that Beyfortus 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 their Beyfortus treatment. Examples of the drug’s commonly reported side effects include:
- injection site reactions*
- rash*
* To learn more about this side effect, see the “Side effects explained” section below.
Mild side effects have been reported with Beyfortus. These include:
- injection site reactions*
- rash*
In most cases, these side effects should be temporary. And some may be easily managed. But if your child has symptoms that are ongoing or bothersome, talk with their doctor.
Beyfortus 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.
Serious side effects other than allergic reaction weren’t reported in studies of Beyfortus. You can read more about allergic reactions in the section below.
If your child develops serious side effects while receiving Beyfortus, call their doctor right away. If the side effects seem life threatening or you think they’re having a medical emergency, immediately call 911 or your local emergency number.
Note: After the Food and Drug Administration (FDA) approves a vaccine, the FDA and the Centers for Disease Control and Prevention (CDC) track side effects of the drug. If you’d like to report a side effect your child had with Beyfortus, visit the Vaccine Adverse Event Reporting System (VAERS) website.
Allergic reactionFor some people, Beyfortus can cause an allergic reaction.
In general, symptoms of allergic reaction can be mild or serious.
What might help
If your child has mild symptoms of an allergic reaction, such as a mild rash, call their doctor right away. They may suggest a treatment to manage your child’s symptoms and can determine whether your child should continue Beyfortus treatment.
If your child has 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 your child has had a serious allergic reaction to Beyfortus, they may have your child switch to a different treatment.
Learn more about some of the side effects Beyfortus may cause.
Injection site reactions
Injection site reactions were a rare side effect reported in studies of Beyfortus. Injection site reactions may cause symptoms at the site of injection, such as:
- pain
- redness or discoloration
- swelling
- thickening or hardening of the skin
These reactions can occur up to 7 days after the dose of Beyfortus is injected.
What might help
If your child has an injection site reaction from Beyfortus treatment, talk with your child’s doctor. They’ll likely recommend applying a cold compress and possibly taking an over-the-counter pain reliever to help with symptom relief.
Rash
A skin rash was an uncommon side effect reported in studies of Beyfortus. However, it was the most common side effect reported in children receiving the drug. A skin rash may cause symptoms such as:
- bumps or raised areas of skin
- itching
- skin redness or discoloration
Rashes were reported within 14 days after receiving a dose of Beyfortus.
What might help
Talk with your child’s doctor if your child develops a skin rash. Their doctor can suggest ways to manage symptoms of the rash.
During your child’s Beyfortus treatment, consider taking notes on any side effects they’re having. You can then share this information with their doctor. This is especially helpful when your child first starts receiving a new drug or using a combination of treatments.
Side effect notes can include things such as:
- what dose of the drug your child was receiving when they had the side effect
- how soon they had the side effect after starting that dose
- what your child’s symptoms were
- how your child’s symptoms affected their daily activities
- what other medications your child was taking
- any other information you feel is important
Sharing notes with your child’s doctor will help them learn more about how Beyfortus affects your child. They can then use this information to adjust your child’s treatment plan if needed.
Below is important information you should consider before starting Beyfortus treatment.
Warnings
Beyfortus can sometimes cause harmful effects in people who have certain conditions. This is known as a drug-condition interaction. Other factors may also affect whether Beyfortus is a good treatment option for your child.
Talk with your child’s doctor about your child’s health history before they start Beyfortus treatment. Be sure to tell them if any of the following factors apply to your child:
- bleeding or bruising problems
- recent use of palivizumab (Synagis) during the current RSV season
- previous allergic reaction to Beyfortus
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.