Vyvgart (efgartigimod alfa-fcab) is a prescription drug used to treat myasthenia gravis (MG) in certain adults. Vyvgart can cause side effects that range from mild to serious. Examples include infusion reactions and blood cell problems.
Specifically, Vyvgart is used to treat generalized myasthenia gravis (gMG) in adults who are anti-acetylcholine receptor (AchR) antibody positive. (“Generalized” MG refers to having muscle weakness in your eyes, arms, legs, or chest.)
Vyvgart is a
Keep reading to learn about common, mild, and serious side effects that Vyvgart can cause. For a general overview of the drug, including details about its uses, see this article.
* The reason “-fcab” appears at the end of the drug’s name is to show that it’s distinct from similar medications that may be created in the future.
Some people may experience mild to serious side effects during Vyvgart treatment. Examples of the drug’s commonly reported side effects include:
- respiratory infection, such as the common cold
- headache
- urinary tract infection (UTI)
- changes to the senses*
- aches or pains in muscles
* To learn more about this side effect, see the “Side effects explained” section.
Mild side effects have been reported with Vyvgart. These include:
- aches or pains in muscles
- headache
- respiratory infection, such as the common cold
- UTI
- changes to the senses*
- mild infusion reactions*
In most cases, these side effects are 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 Vyvgart treatment unless your doctor recommends it.
Vyvgart 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.
Serious side effects have been reported with Vyvgart. These include:
- blood cell problems*
- severe infusion reactions*
If you develop serious side effects during Vyvgart treatment, 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.
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 Vyvgart, visit MedWatch.
Allergic reactionFor some people, Vyvgart can cause an allergic reaction.
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 and can determine whether you should continue Vyvgart treatment.
If you have symptoms of a severe allergic reaction, such as swelling or difficulty 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 Vyvgart, they may have you switch to a different treatment.
Learn more about some of the side effects Vyvgart may cause.
Changes to your senses
Sensory changes, such as to your sense of touch, were uncommon* in Vyvgart studies. Specific symptoms reported include:
- numbness or reduced sensitivity in cheeks, gums, lips, or tongue (oral hypoesthesia)
- numbness or tingling in areas such as arms or legs
- increased sense sensitivity (hyperesthesia), such as to touch, sights, or sounds
* While this side effect was “common” relative to some other side effects of Vyvgart, most people in the drug’s studies did not experience changes to their senses.
What might help
If you have changes to your senses during Vyvgart treatment, talk with your doctor. If they determine Vyvgart is the probable cause of your symptoms, they’ll likely recommend you stop treatment. In this case, they can discuss other treatments for myasthenia gravis with you.
Blood cell problems
Blood cell problems were rare in Vyvgart studies. However, these side effects can be serious.
Reported blood cell problems include:
- low white blood cell count, which typically doesn’t cause symptoms
- low lymphocyte count, which typically doesn’t cause symptoms
- low neutrophil count, which can cause symptoms including fever and skin abscesses
In studies, people receiving Vyvgart treatment had a higher rate of infection, such as UTI, compared with people who received a placebo (infusion with no active drug). This increased risk of infection is believed to be related to the blood cell problems listed above.
Symptoms of an infection can include:
- fever
- cough
- sore throat
- pain while urinating
- mouth sores
If you have an existing blood cell problem, treatment with Vyvgart may worsen it.
What might help
If you have an infection, be sure to tell your doctor before starting Vyvgart treatment. They’ll likely want to treat the infection before prescribing Vyvgart for you.
If you develop symptoms of an infection during treatment with Vyvgart, let your doctor know right away. They can order tests to find possible causes and prescribe an appropriate treatment if available. If the infection is serious, they may temporarily pause your Vyvgart treatment until the infection clears.
Infusion reactions
Both mild and serious infusion reactions were reported in studies of Vyvgart, but these were rare.
Vyvgart comes as a liquid solution for IV infusion. Infusion reactions are side effects that happen during or shortly after (typically within an hour) of receiving a Vyvgart infusion.
Infusion reactions reported with Vyvgart include:
What might help
Since Vyvgart is given as an IV infusion, you’ll receive your doses at a clinic, doctor’s office, or other healthcare setting. Healthcare professionals will be on hand to treat symptoms of an infusion reaction. For example, they can give you medication for lowering high blood pressure if needed.
If you have mild to moderate symptoms, your doctor will likely give your future infusions at a slower rate. They may also give you drugs prior to future Vyvgard infusions to help prevent these reactions.
If you experience a severe infusion reaction, your doctor may permanently stop your Vyvgart treatment.
Keeping track of side effectsDuring Vyvgart 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 a new drug or combination of treatments.
Your side effect notes can include things such as:
- what dose of the drug you were receiving 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
Sharing notes with your doctor will help them learn more about how Vyvgart affects you. They can then use this information to adjust your treatment plan if needed.
Vyvgart can sometimes cause harmful effects in people with certain conditions. This is known as a drug-condition interaction. Other factors may also affect whether Vyvgart is a good treatment option for you.
Talk with your doctor about your health history before starting Vyvgart. Be sure to tell them if any of the following factors apply to you:
- current infection
- blood cell problem, such as low white blood cell count
- previous allergic reaction to Vyvgart
- pregnancy
- breastfeeding
- alcohol consumption
For information on potential interactions between Vyvgart and other drugs, supplements, and more, check out this article.
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.