Vyondys 53 is used to treat Duchenne muscular dystrophy in adults and children who have a certain gene mutation. Your doctor will test you for this gene mutation.

Vyondys 53 was approved by the US Food and Drug Administration (FDA) on an "accelerated" basis. In clinical studies, some people responded to Vyondys 53, but further studies are needed.

Vyondys 53 may also be used for purposes not listed in this medication guide.

Follow all directions on your medicine label and package. Tell each of your healthcare providers about all your medical conditions, allergies, and all medicines you use.

Your doctor will perform blood tests to make sure you do not have conditions that would prevent you from safely using Vyondys 53.

Vyondys 53 is given as an infusion into a vein, usually once per week. A healthcare provider will give you this injection.

Vyondys 53 must be given slowly, and the infusion can take up to 60 minutes to complete.

Your kidney function may need to be checked while you are using this medicine.

Tell your doctor if you have ever had kidney problems.

Tell your doctor if you are pregnant or breastfeeding.

Call your doctor for instructions if you miss an appointment for your Vyondys 53.

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Follow your doctor's instructions about any restrictions on food, beverages, or activity.

Get emergency medical help if you have signs of an allergic reaction: hives, itching, rash, blistering or peeling; fever; difficult breathing; swelling of your face, lips, tongue, or throat.

Vyondys 53 may cause serious side effects. Call your doctor at once if you have:

• pink, brown, or red urine;

• foamy urine; or

• swelling in your face, hands, feet, or stomach.

Common side effects of Vyondys 53 may include:

• headache;

• fever;

• stomach pain;

• falls;

• cough; or

• runny or stuffy nose.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Other drugs may affect Vyondys 53, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell your doctor about all your current medicines and any medicine you start or stop using.