Patient Leaflet Updated 16-Jun-2025 | SANOFI
Beyfortus 50 mg and 100 mg solution for injection in pre-filled syringe
Beyfortus® 50 mg solution for injection in pre-filled syringe
Beyfortus® 100 mg solution for injection in pre-filled syringe
nirsevimab
▼This medicine is subject to additional monitoring. This will allow quick identification of new safety information. You can help by reporting any side effects your child may get. See the end of section 4 for how to report side effects.
1. What Beyfortus is and what it is used for
2. What you need to know before your child is given Beyfortus
3. How and when Beyfortus is given
4. Possible side effects
5. How to store Beyfortus
6. Contents of the pack and other information
Beyfortus is a medicine given as an injection to protect babies and children less than 2 years of age against respiratory syncytial virus (RSV). RSV is a common respiratory virus that usually causes mild symptoms comparable to the common cold. However, especially in babies, vulnerable children and older adults, RSV can cause severe illness, including bronchiolitis (inflammation of the small airways in the lung) and pneumonia (infection of the lungs) that may lead to hospitalisation or even death. The virus is usually more common during the winter.
Beyfortus contains the active ingredient nirsevimab which is an antibody (a protein designed to attach to a specific target) that attaches to a protein that RSV needs to infect the body. By attaching to this protein, Beyfortus blocks its action, thereby stopping the virus from entering and infecting human cells.
Beyfortus is a medicine to protect your child from getting RSV disease.
Your child should not use Beyfortus if he or she is allergic to nirsevimab or any of the other ingredients of this medicine (listed in section 6).
Inform your child’s doctor, pharmacist or nurse if this applies to your child. If you are not sure, check with your child’s doctor, pharmacist or nurse before the medicine is given.
If your child shows signs of a severe allergic reaction contact the doctor immediately.
Tell your doctor or seek medical help immediately if you notice any signs of an allergic reaction, such as:
Talk to your healthcare professional before your child is given Beyfortus if they have low numbers of blood platelets (which help blood clotting), a bleeding problem or bruise easily or if they are taking an anticoagulant (a medicine to prevent blood clots).
In certain chronic health conditions, where too much protein is lost via the urine or the gut, for example nephrotic syndrome and chronic liver disease, the level of protection of Beyfortus may be reduced.
Beyfortus contains 0.1 mg of polysorbate 80 in each 50 mg (0.5 mL) dose and 0.2 mg in each 100 mg (1 mL) dose. Polysorbates may cause allergic reactions. Tell your doctor if your child has any known allergies.
Do not give this medicine to children between the age of 2 and 18 years of age because it has not been studied in this group.
Beyfortus is not known to interact with other medicines. However, tell your doctor, pharmacist or nurse if your child is taking, has recently taken or might take any other medicines.
Beyfortus may be given at the same time as vaccines that are part of the national immunisation program.
Beyfortus is given by a healthcare professional as an injection in the muscle. It is usually given in the outer part of the thigh.
The recommended dose is:
Beyfortus should be given before the RSV season. The virus is usually more common during the winter (known as the RSV season). If your child is born during the winter, Beyfortus should be given after birth.
If your child is to have a heart operation (cardiac surgery), he or she may be given an extra dose of Beyfortus after the operation to ensure they have adequate protection over the remainder of the RSV season.
If you have any further questions on the use of this medicine, ask your doctor, pharmacist or nurse.
Like all medicines, this medicine can cause side effects, although not everybody gets them.
Side effects can include:
Uncommon (may affect up to 1 in 100 children)
Not known (cannot be estimated from available data)
If your child gets any side effects, talk to your doctor, pharmacist or nurse. This includes any possible side effects not listed in this leaflet. You can also report side effects directly via the Yellow Card Scheme website: www.mhra.gov.uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store. By reporting side effects you can help provide more information on the safety of this medicine.
Your doctor, pharmacist or nurse is responsible for storing this medicine and disposing of any unused product correctly. The following information is intended for healthcare professionals.
Keep this medicine out of the sight and reach of children.
Do not use this medicine after the expiry date which is stated on the carton after EXP. The expiry date refers to the last day of that month.
Store in a refrigerator (2°C - 8°C). After removal from the refrigerator, Beyfortus must be protected from light and used within 8 hours or discarded.
Keep the pre-filled syringe in the outer carton in order to protect from light.
Do not freeze, shake or expose to direct heat.
Any unused medicine or waste material should be disposed of in accordance with local requirements.
Beyfortus is a colourless to yellow solution for injection.
Beyfortus is available as:
Not all pack sizes may be marketed.
This leaflet was last revised in March 2025
© Sanofi 2022
BEYFORTUS is a trademark of the Sanofi group of companies.
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