WHY is this medicine prescribed?
Sepiapterin is used to treat hyperphenylalaninemia (HPA; elevated levels of the amino acid phenylalanine) due to phenylketonuria (PKU; disorder where body cannot break down phenylalanine). Sepiapterin is in a class of medications called phenylalanine hydroxylase (PAH) activators. It works by helping the phenylalanine hydroxylase enzyme to break down phenylalanine to tyrosine.
HOW should this medicine be used?
Sepiapterin comes as a powder to be mixed with water or apple juice to be given by mouth. Take with food once a day. Take sepiapterin at around the same time every day.
Take sepiapterin exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.
To take the powder for doses under 1000 mg, place the prescribed number of packets in a large enough container with the prescribed amount of liquid (water or applesauce), stir the contents for 30 seconds or more until it is mixed. Draw up the prescribed volume of the mixture in an oral syringe and give by mouth. Give immediately after mixing. If powder remains in the syringe, draw up more liquid (water or apple juice), and give immediately. Repeat this process until all powder particles are gone. Eat additional food after taking the entire dose.
For doses greater than 1000 mg, you may place the powder from the prescribed number of packets in prescribed amount of water, apple juice, strawberry jam or applesauce. If placing in water or apple juice, follow the directions above. If placing in strawberry jam or applesauce, mix for 60 seconds or until completely mixed. Eat the entire mixture immediately. Eat additional food after taking the entire dose.
If the dose is not taken immediately after mixing, you can cover and store the mixture at room temperature for up to 6 hours or store in the refrigerator for up to 24 hours. Make sure to mix for 30 seconds (liquid) or 60 seconds (applesauce or strawberry jam) before taking. Throw away any of the mixture not given in 6 hours (if at room temperature) or 24 hours (if in refrigerator).
Your prescription for sepiapterin will come with instructions for use. Read these instructions carefully and ask your doctor or pharmacist if there are parts you do not understand.
Sepiapterin controls HPA but does not cure it. Do not stop taking sepiapterin without talking to your doctor.
Are there OTHER USES for this medication?
This medication may be prescribed for other uses; ask your doctor or pharmacist for more information.
What SPECIAL PRECAUTIONS should I follow?
Before taking sepiapterin,
What SPECIAL DIETARY instructions should I follow?
Your doctor will prescribe a protein and a phenylalanine-restricted diet while you are receiving sepiapterin. Follow this diet carefully.
What should I do IF I FORGET to take a dose?
Take the missed dose as soon as you remember it. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.
What SIDE EFFECTS can this medicine cause?
Sepiapterin may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:
Some side effects can be serious. If you experience any of these symptoms, call your doctor immediately:
Septiapterin 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).
What should I do in case of OVERDOSE?
In case of overdose, call the poison control helpline at 1-800-222-1222. Information is also available online at http://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.
What should I know about STORAGE and DISPOSAL of this medication?
Keep this medication in the container it came in, tightly closed, and out of reach of children. Store it at room temperature and away from excess heat and moisture (not in the bathroom).
Keep all medication out of sight and reach of children as many containers are not child-resistant. Always lock safety caps. Place the medication in a safe location - one that is up and away and out of their sight and reach. http://www.upandaway.org
Dispose of unneeded medications in a way so that pets, children, and other people cannot take them. Do not flush this medication down the toilet. Use a medicine take-back program. Talk to your pharmacist about take-back programs in your community. Visit the FDA's Safe Disposal of Medicines website http://goo.gl/c4Rm4p for more information.
What OTHER INFORMATION should I know?
Keep all appointments with your doctor and the laboratory. Your doctor will order certain lab tests to check your body's response to sepiapterin. If you miss a lab appointment, call your doctor right away to reschedule.
Before having any laboratory test, tell your doctor and the laboratory personnel that you are taking sepiapterin.
Do not let anyone else take your medication. Ask your pharmacist any questions you have about refilling your prescription.
Keep a written list of all of the prescription and nonprescription (over-the-counter) medicines, vitamins, minerals, and dietary supplements you are taking. Bring this list with you each time you visit a doctor or if you are admitted to the hospital. You should carry the list with you in case of emergencies.
This report on medications is for your information only, and is not considered individual patient advice. Because of the changing nature of drug information, please consult your physician or pharmacist about specific clinical use.
The American Society of Health-System Pharmacists, Inc. represents that the information provided hereunder was formulated with a reasonable standard of care, and in conformity with professional standards in the field. The American Society of Health-System Pharmacists, Inc. makes no representations or warranties, express or implied, including, but not limited to, any implied warranty of merchantability and/or fitness for a particular purpose, with respect to such information and specifically disclaims all such warranties. Users are advised that decisions regarding drug therapy are complex medical decisions requiring the independent, informed decision of an appropriate health care professional, and the information is provided for informational purposes only. The entire monograph for a drug should be reviewed for a thorough understanding of the drug's actions, uses and side effects. The American Society of Health-System Pharmacists, Inc. does not endorse or recommend the use of any drug. The information is not a substitute for medical care.
AHFS® Patient Medication Information™ Copyright, 2025. The American Society of Health-System Pharmacists®, 4500 East-West Highway, Suite 900, Bethesda, Maryland. All Rights Reserved. Duplication for commercial use must be authorized by ASHP.
Selected Revisions: September 15, 2025.