Efgartigimod alfa-fcab injection is used to treat a certain form of myasthenia gravis (MG; a disorder of the nervous system that causes muscle weakness). Efgartigimod alfa-fcab is in a group of medications called monoclonal antibodies. It works by reducing a certain natural substance in the body that causes symptoms of myasthenia gravis.

Efgartigimod alfa-fcab comes as a solution (liquid) to be injected slowly into a vein over 60 minutes by a healthcare provider. It is usually given once a week for 4 weeks. The cycle may be repeated as recommended by your doctor, but no sooner than at least 50 days after your last weekly dose. The length of your treatment depends on how well your body responds to the medication and any side effects that you experience.

Efgartigimod alfa-fcab injection may cause serious allergic reactions. Your healthcare provider will watch you carefully while you are receiving efgartigimod alfa-fcab injection and for 1 hour after you receive the medication. Your doctor may slow or stop your infusion if you have an allergic reaction. If you experience any of the following symptoms, tell your doctor immediately: chest pain; feeling faint; rash; hives; swelling of the eyes, face, lips, tongue, or throat; hoarseness; or difficulty breathing or swallowing.

Ask your pharmacist or doctor for a copy of the manufacturer's information for the patient.

Before receiving efgartigimod alfa-fcab injection,

• tell your doctor and pharmacist if you are allergic to efgartigimod alfa-fcab, any other medications, or any of the ingredients in efgartigimod alfa-fcab injection. Ask your pharmacist for a list of the ingredients.
• tell your doctor and pharmacist what other prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take. Your doctor may need to change the doses of your medications or monitor you carefully for side effects.
• tell your doctor if you have an infection or have ever had an infection that keeps coming back or if you have or ever had any other medical conditions.
• tell your doctor if you are pregnant, plan to become pregnant, or are breast-feeding. If you become pregnant while receiving efgartigimod alfa-fcab injection, call your doctor.
• do not have any vaccinations without talking to your doctor.

If you miss an appointment to receive a dose of efgartigimod alfa-fcab injection, call your doctor right away.

In case of overdose, call the poison control helpline at 1-800-222-1222. Information is also available online at https://www.poisonhelp.org/help. If the victim has collapsed, had a seizure, has trouble breathing, or can't be awakened, immediately call emergency services at 911.

Unless your doctor tells you otherwise, continue your normal diet.

Efgartigimod alfa-fcab may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

• headache
• pain, burning, numbness, or tingling in the hands, feet, or mouth
• muscle pain

Some side effects can be serious. If you experience any of these symptoms, call your doctor immediately:

• fever, sore throat, chills, cough, or other signs of infection
• pain or burning on urination or frequent urination

Efgartigimod alfa-fcab may cause other side effects. Call your doctor if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration's (FDA) MedWatch Adverse Event Reporting program online (http://www.fda.gov/Safety/MedWatch) or by phone (1-800-332-1088).

This medication may be prescribed for other uses; ask your doctor or pharmacist for more information.

Keep all appointments with your doctor.

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.