This medication is used by people with a certain inherited condition (phenylketonuria) to reduce high levels of a certain substance (phenylalanine) that builds up in the blood. Having high levels of phenylalanine in the blood may cause brain damage, heart problems, an abnormally small head size, and behavioral problems. Pegvaliase works by breaking down phenylalanine in the blood.

Along with using this medication, you should follow a special diet to control your blood phenylalanine levels. Ask your doctor for details.

Read the Medication Guide and Instructions for Use provided by your pharmacist before you start using pegvaliase and each time you get a refill. Ask your health care professional how to prepare and use this medication. If you have any questions, ask your doctor or pharmacist. Carry the Patient Wallet Card with you at all times. Show the card to all of your health care providers to let them know that you are being treated with pegvaliase.

Inject this medication under the skin as directed by your doctor, usually starting with once weekly for 4 weeks, then gradually increasing over 5 weeks to once daily. The injection is given in the thigh, abdomen, top of the buttocks, or upper arm. The dosage is based on your medical condition and response to treatment. Your doctor may prescribe other medications (such as antihistamines, acetaminophen) before each dose to help prevent side effects. Carefully follow your doctor's directions.

Take the medication out of the refrigerator at least 30 minutes before you inject it to allow it to reach room temperature. Do not warm up this medication any other way (for example, do not heat it in the microwave or place it in hot water). Do not shake the medication. Before using, check this product for particles or discoloration. If either is present, do not use the liquid. Before injecting each dose, clean the skin you are going to inject into (the injection site) with rubbing alcohol. Change the injection site each time to lessen injury under the skin. Do not inject into skin that is injured, tender, hard, red, bruised, or tattooed, or into moles, scars, birthmarks or rashes. To lessen bruising, do not rub the injection site after a shot. Learn how to store and discard medical supplies safely.

Use this medication regularly to get the most benefit from it. To help you remember, mark your calendar with a reminder.

See also Warning section.

Redness, itching, pain, or bruising at the injection site may occur. Muscle/joint/back/neck pain, headache, mouth/throat/abdominal pain, dizziness, cough, or tiredness may also occur. If any of these effects last or get worse, tell your doctor or pharmacist promptly.

Temporary hair loss may occur. Normal hair growth should return if treatment is ended.

Remember that this medication has been prescribed because your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

Pegvaliase can commonly cause a rash that is usually not serious. However, you may not be able to tell it apart from a rare rash that could be a sign of a severe reaction. Get medical help right away if you develop any rash.

This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.

In the US - Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.

In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

Before using pegvaliase, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

Before using this medication, tell your doctor or pharmacist your medical history.

Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

During pregnancy, this medication should be used only when clearly needed. Discuss the risks and benefits with your doctor.

It is unknown if this medication passes into breast milk. Consult your doctor before breastfeeding.

Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.

If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call 1-800-222-1222. Canada residents can call 1-844-764-7669.

Do not share this medication with others.

Lab and/or medical tests (such as phenylalanine levels) must be done before you start using this medication and while you are using it. Keep all medical and lab appointments.

If you miss a dose, skip the missed dose. Use your next dose at the regular time. Do not double the dose to catch up.

Store in the refrigerator. Do not freeze. Keep the medication in the original package to protect from light. This medication may also be stored at room temperature if needed. If the medication is stored at room temperature, do not put it back in the refrigerator and discard after 30 days. Keep all medications away from children and pets.

Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company.