Javygtor is used to lower blood levels of phenylalanine in adults and children at least one month old with a certain type of phenylketonuria (PKU).

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

Use only as directed. Tell your doctor if you use other medicines or have other medical conditions or allergies.

Follow all directions on your prescription label and read all medication guides or instruction sheets. Your doctor may occasionally change your dose. Use the medicine exactly as directed.

Javygtor can cause phenylalanine levels to get too low in children younger than 7 years old who use this medicine.

Take the medicine with food at the same time each day.

You may swallow the tablet whole or dissolve it in 4 to 8 ounces of water or apple juice.

• It will take a few minutes for the tablet to dissolve, and you may see small pieces in the liquid. These pieces are safe for you to swallow.

• Stir the mixture and then drink all of it within 15 minutes after the tablet dissolves.

• To get the entire dose, add a little more water to the same glass, swirl gently and drink right away.

• You may also crush the tablet and mix it with a small amount of soft food such as pudding or applesauce.

The powder for oral solution must be dissolved in 4 to 8 ounces of water or apple juice.

• If you are giving this medicine to a baby who weighs less than 22 pounds, you may dissolve the powder in as little as 1 teaspoon of water or apple juice. Then give the liquid to the baby using an oral dosing syringe. If you do not have a dosing syringe, ask your pharmacist for one.

• Stir the mixture and then drink all of it within 30 minutes after the powder dissolves.

• You may also mix the powder with a small amount of soft food such as pudding or applesauce.

• Make sure the powder is completely dissolved before drinking or eating the mixture.

Doses are based on weight in children and teenagers. Your child's dose may change if the child gains or loses weight.

You may need to follow a special diet. Follow all instructions of your doctor or dietitian. Learn about the foods you should eat or avoid.

While using Javygtor, you may need frequent blood tests.

Store at room temperature away from moisture and heat. Keep the bottle tightly closed when not in use.

You should not use Javygtor if you are allergic to it.

Tell your doctor if you have ever had:

• stomach ulcer or bleeding; or

• loss of appetite, or if you are malnourished.

It is not known if Javygtor will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant.

If you are pregnant, your name may be listed on a pregnancy registry to track the effects of sapropterin on the baby.

Ask a doctor if it is safe to breastfeed while using Javygtor.

Take the medicine as soon as you can, but skip the missed dose if it is almost time for your next dose. Do not take two doses in a day.

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, rash, wheezing, cough, difficult breathing, nausea, feeling light-headed, flushing (warmth, redness, or tingly feeling), swelling of your face, lips, tongue, or throat.

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

• behavior changes, seizures, or problems with speech;

• fever, loss of appetite, difficulty swallowing, throat pain, severe stomach discomfort or pain, nausea, vomiting;

• bloody or tarry stools, coughing up blood or vomit that looks like coffee grounds; or

• hyperactive behavior, such as fidgeting or moving around often, or talking too much.

Common side effects of Javygtor may include:

• headache;

• diarrhea;

• vomiting; or

• runny or stuffy nose, sore throat, cough.

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.

Tell your doctor about all your other medicines, especially:

• levodopa;

• methotrexate, valproic acid, phenobarbital, trimethoprim; or

• medicine to treat impotence or pulmonary arterial hypertension--sildenafil (Viagra, Revatio), avanafil (Stendra), tadalafil (Adcirca, Cialis) vardenafil (Levitra, Staxyn).

This list is not complete. Other drugs may affect Javygtor, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible drug interactions are listed here.