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Relapsing MS
support resources

Find resources to help yourself or the person you care about

Whether you are living with relapsing multiple sclerosis (MS) or caring for someone with relapsing MS, it’s important to have a support system you can count on. And the more support you get, the more you can help yourself or the one you care about.

Some resources you may find helpful along the way:

Questions for your healthcare provider

Download a guide to help start a conversation with your healthcare provider about your relapsing MS treatment.

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Explore more about PLEGRIDY

Could PLEGRIDY be right for you? Download this brochure to learn more about relapsing MS treatment.

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FAQ

Get answers to frequently asked questions about PLEGRIDY.

Learn more

PLEGRIDY Pen injection video

See how to prepare and give an injection with the PLEGRIDY Pen for subcutaneous use.

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Intramuscular PLEGRIDY injection video

Watch a step-by-step video about taking PLEGRIDY with the prefilled syringe for intramuscular use.

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More to explore with PLEGRIDY

Think PLEGRIDY might be right for you?

In a clinical study, PLEGRIDY was shown to work in 3 key areas.
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What is PLEGRIDY® (peginterferon beta-1a)?

PLEGRIDY is a prescription medicine used to treat relapsing forms of multiple sclerosis (MS), to include clinically isolated syndrome, relapsing-remitting disease, and active secondary progressive disease in adults.

It is not known if PLEGRIDY is safe and effective in people under 18 or over 65 years of age.

Important Safety Information

Who should not take PLEGRIDY?

  • Do not take PLEGRIDY if you are allergic to interferon beta or peginterferon, or any of the other ingredients in PLEGRIDY

What is the most important information I should know about PLEGRIDY?

PLEGRIDY can cause serious side effects, including:

  • Liver problems, or worsening of liver problems, including liver failure and death. Symptoms may include yellowing of your skin or the white part of your eye, nausea, loss of appetite, tiredness, bleeding more easily than normal, confusion, sleepiness, dark colored urine, and pale stools. During your treatment with PLEGRIDY you will need to see your healthcare provider regularly. You will have regular blood tests to check for these possible side effects

  • Depression or suicidal thoughts. Symptoms may include new or worsening depression (feeling hopeless or bad about yourself), thoughts of hurting yourself or suicide, irritability (getting upset easily), nervousness, or new or worsening anxiety

Call your healthcare provider right away if you have any of the symptoms listed above.

Before taking PLEGRIDY, tell your healthcare provider about all of your medical conditions, including if you:

  • Are being treated for a mental illness or had treatment in the past for any mental illness, including depression and suicidal behavior

  • Have or had liver problems, low blood cell counts, bleeding problems, heart problems, seizures (epilepsy), thyroid problems, or any kind of autoimmune disease (where the body’s immune system attacks the body’s own cells)

  • Have or had an allergic reaction to rubber or latex. The tip of the cap of the PLEGRIDY prefilled syringe for intramuscular use is made of natural rubber latex

  • Are pregnant or plan to become pregnant. It is not known if PLEGRIDY can harm your unborn baby

  • Are breastfeeding or plan to breastfeed. PLEGRIDY may pass into your breastmilk. Talk to your healthcare provider about the best way to feed your baby if you take PLEGRIDY

Tell your healthcare provider about all the medicines you take, including prescription and over-the-counter medicines, vitamins, and herbal supplements.

What are the possible side effects of PLEGRIDY?

PLEGRIDY may cause serious side effects, including:

  • serious allergic reactions. Serious allergic reactions can happen if you take PLEGRIDY. Symptoms may include itching, swelling of the face, eyes, lips, tongue, or throat, trouble breathing, feeling faint, anxiousness, skin rash, hives, or skin bumps. Get emergency help right away if you have any of these symptoms. Talk to your healthcare provider before taking another dose of PLEGRIDY

  • injection site reactions. PLEGRIDY may commonly cause redness, pain, itching or swelling at the place where the injection was given. Call your healthcare provider right away if an injection site becomes swollen and painful or the area looks infected. You may have a skin infection or an area of severe skin damage (necrosis) requiring treatment by a healthcare provider

  • heart problems, including congestive heart failure. Call your healthcare provider right away if you have worsening symptoms of heart failure such as shortness of breath or swelling of your lower legs or feet while using PLEGRIDY

    • Some people using PLEGRIDY may have other heart problems, including low blood pressure, fast or abnormal heartbeat, chest pain, heart attack, or a heart muscle problem (cardiomyopathy)

  • blood problems and changes in your blood tests. PLEGRIDY can decrease your white blood cells or platelets, which can cause an increased risk of infection, bleeding, or anemia and can cause changes in your liver function tests. Your healthcare provider will do tests to monitor for side effects while you use PLEGRIDY

  • thrombotic microangiopathy (TMA). TMA is a condition that involves injury to the smallest blood vessels in your body. TMA can also cause injury to your red blood cells (the cells that carry oxygen to your organs and tissues) and your platelets (cells that help your blood clot) and can sometimes lead to death. Your healthcare provider may tell you to stop taking PLEGRIDY if you develop TMA

  • pulmonary arterial hypertension. Pulmonary arterial hypertension can occur with interferon beta products, including PLEGRIDY. Symptoms may include new or increasing fatigue or shortness of breath. Contact your healthcare provider right away if you develop these symptoms

  • autoimmune diseases. Problems with easy bleeding or bruising (idiopathic thrombocytopenia), thyroid gland problems (hyperthyroidism and hypothyroidism), and autoimmune hepatitis have happened in some people who use interferon beta

  • seizures. Some people have had seizures while taking PLEGRIDY, including people who have never had seizures before

The most common side effects of PLEGRIDY include:

  • flu-like symptoms. Many people who take PLEGRIDY have flu-like symptoms especially early in the course of therapy. These symptoms are not really the flu. You cannot pass it on to anyone else

    • You may be able to manage these flu-like symptoms by taking over-the-counter pain and fever reducers and drinking plenty of water

Flu-like symptoms or other common side effects of PLEGRIDY may include: headache, muscle and joint aches, fever, chills, or tiredness.

These are not all of the possible side effects of PLEGRIDY.

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-10881-800-FDA-1088.

Please see full Prescribing Information and Medication Guide.

This information does not take the place of talking with your healthcare provider about your medical condition or your treatment.

©2026 Biogen. All rights reserved. All trademarks are the property of their respective owners.
This site is intended for US residents aged 18 and older. The information on this site is not intended to provide medical advice. Any questions should be directed to a healthcare provider.
PLG-US-1210v3 07/26

©2026 Biogen. All rights reserved. All trademarks are the property of their respective owners.
This site is intended for US residents aged 18 and older. The information on this site is not intended to provide medical advice. Any questions should be directed to a healthcare provider.
PLG-US-1210v3 07/26