Pegvaliase

This information from UpToDate^® Lexidrug^™ explains what you need to know about this medication, including what it’s used for, how to take it, its side effects, and when to call your healthcare provider.

Brand Names: US

Palynziq

Brand Names: Canada

Palynziq

What is this drug used for?

• It is used to treat phenylketonuria (PKU).

What do I need to tell the doctor BEFORE my child takes this drug?

• If your child is allergic to this drug; any part of this drug; or any other drugs, foods, or substances. Tell the doctor about the allergy and what signs your child had.

This drug may interact with other drugs or health problems.

Tell the doctor and pharmacist about all of your child’s drugs (prescription or OTC, natural products, vitamins) and health problems. You must check to make sure that it is safe to give this drug with all of your child’s other drugs and health problems. Do not start, stop, or change the dose of any drug your child takes without checking with the doctor.

What are some things I need to know or do while my child takes this drug?

• Tell all of your child’s health care providers that your child is taking this drug. This includes your child’s doctors, nurses, pharmacists, and dentists.
• Have your child avoid tasks or actions that call for alertness until you see how this drug affects your child. These are things like riding a bike, playing sports, or using items such as scissors, lawnmowers, electric scooters, toy cars, or motorized vehicles.
• Be sure the patient safety card is with your child at all times.
• Have blood work checked as you have been told by the doctor. Talk with the doctor.
• Have your child follow the diet plan your child’s doctor told you about.
• Skin reactions that spread on the skin are common with this drug and have lasted for at least 14 days. These reactions have included itching, rash, and redness. Skin reactions could also be a sign of an allergic reaction. Talk with the doctor about which skin reactions to call about right away.

If your child is pregnant or breast-feeding a baby:

• This drug may cause harm to the unborn baby if your child takes it during pregnancy.
• If your child gets pregnant while taking this drug or within 1 month after the last dose, call the doctor right away.
• Tell the doctor if your child is breast-feeding a baby. You will need to talk about any risks to the baby.

What are some side effects that I need to call my child’s doctor about right away?

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your child’s doctor or get medical help right away if your child has any of the following signs or symptoms that may be related to a very bad side effect:

• Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.
• Infections have happened where this drug was given. Sometimes the infections were severe. Some needed treatment in the hospital, including surgery. Call the doctor right away if your child has blisters, scabs, open wounds, or signs of an infection where this drug was given like redness that does not go away, oozing, warmth, swelling, or tenderness.

What are some other side effects of this drug?

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your child’s doctor or get medical help if any of these side effects or any other side effects bother your child or do not go away:

• Irritation where the shot is given.
• Back, muscle, joint, arm, or leg pain.
• Headache.
• Diarrhea, stomach pain, upset stomach, or throwing up.
• Mouth pain.
• Throat pain.
• Cough.
• Feeling tired or weak.
• Anxiety.
• Hair loss.
• Stuffy nose.

These are not all of the side effects that may occur. If you have questions about side effects, call your child’s doctor. Call your child’s doctor for medical advice about side effects.

You may report side effects to your national health agency.

How is this drug best given?

Give this drug as ordered by your child’s doctor. Read all information given to you. Follow all instructions closely.

• It is given as a shot into the fatty part of the skin in the upper arm, thigh, buttocks, or stomach area.
• Other drugs may be given before this drug to help avoid side effects.
• Do not give into skin within 2 inches (5 cm) of the belly button.
• If you will be giving your child the shot, your child’s doctor or nurse will teach you how to give the shot.
• Wash your hands before and after use.
• If stored in a refrigerator, let this drug come to room temperature before using it. Leave it at room temperature for at least 30 minutes. Do not heat this drug.
• Do not give into a mole, scar, birthmark, or rash. Do not give into skin that is red, tattooed, irritated, burned, tender, bruised, hard, or damaged.
• Do not give into an infected area of skin.
• Do not shake.
• Do not use if the solution is cloudy, leaking, or has particles.
• This drug is colorless to a faint yellow. Do not use if the solution changes color.
• Move site where you give the shot each time.
• If your child’s dose is more than 1 injection, you may give in the same body part. However, do not give injections within 2 inches (5 cm) of each other.
• Throw away needles in a needle/sharp disposal box. Do not reuse needles or other items. When the box is full, follow all local rules for getting rid of it. Talk with a doctor or pharmacist if you have any questions.

What do I do if my child misses a dose?

• Skip the missed dose and go back to your child’s normal time.
• Do not give 2 doses at the same time or extra doses.

How do I store and/or throw out this drug?

• Store in a refrigerator. Do not freeze.
• Store in the original container to protect from light.
• If needed, you may store at room temperature.
• If stored at room temperature, throw away any unused drug after 30 days or after the expiration date, whichever comes first.
• Do not put this drug back in the refrigerator after it has been stored at room temperature.
• Keep all drugs in a safe place. Keep all drugs out of the reach of children and pets.
• Throw away unused or expired drugs. Do not flush down a toilet or pour down a drain unless you are told to do so. Check with your pharmacist if you have questions about the best way to throw out drugs. There may be drug take-back programs in your area.

General drug facts

• If your child’s symptoms or health problems do not get better or if they become worse, call your child’s doctor.
• Do not share your child’s drug with others and do not give anyone else’s drug to your child.
• Some drugs may have another patient information leaflet. If you have any questions about this drug, please talk with your child’s doctor, nurse, pharmacist, or other health care provider.
• If you think there has been an overdose, call your poison control center or get medical care right away. Be ready to tell or show what was taken, how much, and when it happened.

Consumer Information Use and Disclaimer

This generalized information is a limited summary of diagnosis, treatment, and/or medication information. It is not meant to be comprehensive and should be used as a tool to help the user understand and/or assess potential diagnostic and treatment options. It does NOT include all information about conditions, treatments, medications, side effects, or risks that may apply to a specific patient. It is not intended to be medical advice or a substitute for the medical advice, diagnosis, or treatment of a health care provider based on the health care provider’s examination and assessment of a patient’s specific and unique circumstances. Patients must speak with a health care provider for complete information about their health, medical questions, and treatment options, including any risks or benefits regarding use of medications. This information does not endorse any treatments or medications as safe, effective, or approved for treating a specific patient. UpToDate, Inc. and its affiliates disclaim any warranty or liability relating to this information or the use thereof. The use of this information is governed by the Terms of Use, available at https://www.wolterskluwer.com/en/know/clinical-effectiveness-terms.

Last Reviewed Date

2026-03-18

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