A long-acting interferon injection for relapsing multiple sclerosis
Peginterferon beta-1a
A long-acting interferon injection used to treat relapsing multiple sclerosis.
What is Peginterferon beta-1a?
Peginterferon beta-1a is a specialist medicine used to treat relapsing multiple sclerosis, a condition in which the immune system damages the nerves and causes attacks (relapses) of symptoms. It is a long-acting form of interferon beta, given as an injection under the skin every couple of weeks to reduce how often relapses happen and slow the disease. The most common side effects are flu-like symptoms after each injection and reactions where the injection is given. It can also affect mood (including depression), the liver and blood counts, so it is used under specialist care with regular monitoring.
Education and reference only. This is a plain-language guide to Peginterferon beta-1a — it deliberately contains no doses. Doses depend on the person, the brand and the reason for treatment, and belong with your prescriber. Always check the BNF, the product labelling (SmPC) and follow medical advice.
What it is
Peginterferon beta-1a is a medicine used to treat relapsing forms of multiple sclerosis (MS), a long-term condition in which the body's own immune system attacks the protective covering around nerves, leading to attacks of symptoms called relapses. It is a version of interferon beta that has been modified (pegylated) so it lasts longer in the body, which means it can be given less often than older interferon injections. It is given under the skin as a regular injection and is one of the disease-modifying treatments that aim to reduce relapses rather than treat an attack once it has started. It is prescribed and supervised by an MS specialist team.
How it works
Interferon beta is a natural substance involved in calming and regulating the immune system. In relapsing MS, the immune system mistakenly attacks the nerves, and peginterferon beta-1a is thought to dampen down this harmful immune activity, which reduces the inflammation that damages nerves. By doing this over time, it lowers how often relapses happen and can slow the build-up of disability. Because it has been pegylated to make it last longer, it keeps working between doses and so is given less frequently than standard interferon. It is a preventive, disease-modifying treatment, taken regularly rather than to treat a relapse in progress.
Company & origin
Originated / developed by: Specialist manufacturer.
A specialist long-acting interferon injection used in the UK to treat relapsing forms of multiple sclerosis.
Practical use
How to take Peginterferon beta-1a
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- Inject it under the skin on the regular schedule your MS team sets, using the technique you have been trained in.
- Rotate where you inject to reduce reactions at the injection site.
- To ease flu-like symptoms, you may be advised to inject in the evening and take paracetamol or ibuprofen around the time of the injection.
- Attend regular blood tests so your liver and blood counts can be checked.
- Report any low mood, depression or thoughts of self-harm to your team straight away.
Weighing it up
Advantages & disadvantages of Peginterferon beta-1a
Advantages
- Reduces how often relapses happen in relapsing multiple sclerosis and can slow the disease.
- Long-acting, so it is given less often than older interferon injections.
- Can be self-injected at home after training.
Disadvantages
- Commonly causes flu-like symptoms after injections, at least at first.
- Commonly causes reactions where the injection is given.
- Can affect mood (including depression), the liver and blood counts, so regular monitoring is needed.
Practical use
Good to know
The most common thing to expect with peginterferon beta-1a is flu-like symptoms, such as aches, chills and a high temperature, after an injection; these often ease over the first weeks and can usually be helped by taking the injection in the evening and using paracetamol or ibuprofen as advised. Reactions where the injection is given, such as redness, pain or swelling, are also common, and rotating the injection site helps. It is important to be aware that it can affect mood, including causing or worsening depression, so any low mood or thoughts of self-harm should be reported straight away. It can also affect the liver and the blood counts, which is why regular blood tests are part of treatment. It is a preventive treatment that reduces relapses rather than treating a relapse that is already happening, so it needs to be taken consistently.
Who should not take it / use with caution
- People who have had a serious allergic reaction to interferon beta should not use it.
- It is used with great caution, or avoided, in people with severe depression or thoughts of self-harm.
- It is used with caution in people with significant liver disease or certain blood problems.
- It is used with care in pregnancy, where the specialist team weighs the benefits and risks.
Monitoring
- Regular blood tests to check liver function and blood counts.
- Reviewing mood and watching for depression.
- Reviewing how well relapses are being controlled and how the injections are tolerated.
Side effects
- Flu-like symptoms such as aches, chills, fever and tiredness after injections.
- Redness, pain or swelling where the injection is given.
- Low mood or depression, which should be reported promptly.
- Changes in liver blood tests or blood counts, which monitoring is designed to catch.
Key interactions
- Medicines that affect the liver may need extra care, so tell your team about all your medicines.
- It can affect blood counts, so caution is needed with medicines that do the same.
- There are few other well-established routine interactions, but always give a full medicines list.
Available as: A solution for injection under the skin, often given by the patient.
Answers
Peginterferon beta-1a: frequently asked questions
What is peginterferon beta-1a used for?
It is used to treat relapsing multiple sclerosis, reducing how often relapses happen and helping to slow the disease.
Why do I feel flu-like after the injection?
Flu-like symptoms such as aches, chills and fever are common with interferons, especially at first; injecting in the evening and using paracetamol or ibuprofen as advised can help.
How often is it given?
It is long-acting, so it is given as an injection under the skin every couple of weeks, less often than older interferon treatments.
Can it affect my mood?
Yes, it can affect mood and may cause or worsen depression, so any low mood or thoughts of self-harm should be reported to your team straight away.
Does it treat a relapse?
No. It is a preventive, disease-modifying treatment that reduces how often relapses happen; a relapse that is already happening is treated separately by your team.
The wider class
About Interferon (multiple sclerosis treatment)
Peginterferon beta-1a belongs to the interferon (multiple sclerosis treatment) class. For how the class as a whole works, its shared safety principles and monitoring, see the full guide.
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Authoritative sources
- BNF
- NICE CKS
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