Skip to Content


Generic Name: peginterferon beta-1a (peg in ter FEAR on BAY ta - 1A)
Brand Names: Plegridy

Medically reviewed by Last updated on Jan 10, 2019.

What is Plegridy?

See also: Aubagio

Plegridy (pPeginterferon beta-1a) is made from human proteins. Interferons stimulate the body's immune responses to infection or disease.

Plegridy is used to treat relapsing multiple sclerosis (MS). This medicine will not cure multiple sclerosis, it will only decrease the frequency of relapse symptoms.

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

Important information

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, you will need to see your healthcare provider and 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 this medicine

You should not use Plegridy if you are allergic to peginterferon or other interferons (Alferon, Avonex, Betaseron, Extavia, Intron, Rebetron, Rebif, and others).

To make sure Plegridy is safe for you, tell your doctor if you have:

  • liver disease;

  • kidney disease;

  • heart disease;

  • a history of depression, mental illness, or suicidal thoughts or actions;

  • a bleeding or blood clotting disorder;

  • a thyroid disorder;

  • epilepsy or other seizure disorder; or

  • an autoimmune disorder such as rheumatoid arthritis, lupus, or psoriasis.

It is not known whether Plegridy 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. This is to track the outcome of the pregnancy and to evaluate any effects of Plegridy on the baby.

It is not known whether peginterferon beta-1a passes into breast milk or if it could harm a nursing baby. Tell your doctor if you are breast-feeding a baby.

Plegridy is not approved for use by anyone younger than 18 years old.

How is Plegridy given?

Plegridy is usually given once every 2 weeks. Follow all directions on your prescription label. Your doctor may occasionally change your dose to make sure you get the best results. Do not take this medicine in larger or smaller amounts or for longer than recommended.

Plegridy is injected under the skin. You may be shown how to use injections at home. Do not give yourself this medicine if you do not understand how to use the injection and properly dispose of used needles and syringes.

Use a different place on your stomach, thigh, or upper arm each time you give the injection. Your care provider will show you the best places on your body to inject Plegridy. Do not inject into the same place two times in a row.

About 2 hours after your injection, check for skin redness, swelling, or pain where you gave the injection.

Call your doctor if you have a skin reaction to Plegridy that does not go away within a few days.

Plegridy can cause flu-like symptoms. Your doctor may recommend taking a pain reliever or fever reducer such as aspirin, acetaminophen (Tylenol), or ibuprofen (Advil, Motrin) on the days you receive your injections.

While using Plegridy, you may need frequent blood tests.

Store prefilled syringes or injection pens in their original container in the refrigerator. Keep the carton closed and always protect the medicine from light.

Do not freeze Plegridy, and throw away the medicine if it has become frozen.

About 30 minutes before your injection, take the syringe or pen out of the refrigerator and allow it to reach room temperature. Do not warm the medicine under hot water.

If you do not have access to a refrigerator, store Plegridy at cool room temperature and return it to a refrigerator when possible. This medicine should not be out of a refrigerator for longer than a total of 30 days.

Each single-use prefilled syringe or injection pen is for one use only. Throw away after one use, even if there is still some medicine left in it after injecting your dose.

Use a disposable needle and syringe only once. Follow any state or local laws about throwing away used needles and syringes. Use a puncture-proof "sharps" disposal container (ask your pharmacist where to get one and how to throw it away). Keep this container out of the reach of children and pets.

Plegridy dosing information

Usual Adult Dose for Multiple Sclerosis:

Initial dose: 63 mcg injected subcutaneously on day 1, 94 mcg on day 15 (14 days later), reaching the full dose of 125 mcg on day 29 (after another 14 days)
Maintenance dose:125 mcg injected subcutaneously every 14 days

-Patient should be advised to rotate sites for subcutaneous injections. The usual sites for subcutaneous injections are abdomen, back of the upper arm, and thigh.
-Prophylactic and concurrent use of analgesics and/or antipyretics may prevent or reduce flu-like symptoms sometimes experienced during treatment.

What happens if I miss a dose?

Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

What should I avoid while using Plegridy?

Avoid injecting this medicine into skin that is red, bruised, irritated, scarred, or infected.

Plegridy side effects

Get emergency medical help if you have signs of an allergic reaction to Plegridy: hives, itching, bumps on your skin; feeling anxious or light-headed; difficult breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have:

  • seizure (convulsions);

  • shortness of breath (even with mild exertion), swelling, rapid weight gain;

  • a light-headed feeling, like you might pass out;

  • chest pain or pressure, fast or irregular heart rate;

  • mood or behavior changes, anxiety, irritability, new or worsening depression, thoughts about suicide or hurting yourself;

  • pain, burning, irritation, or skin changes where the injection was given;

  • low blood platelets - easy bruising, unusual bleeding (nose, mouth, vagina, or rectum), purple or red pinpoint spots under your skin;

  • low red blood cells (anemia) - pale skin, feeling light-headed or short of breath, rapid heart rate, trouble concentrating;

  • low white blood cell counts - fever, swollen gums, painful mouth sores, pain when swallowing, skin sores, cold or flu symptoms, cough, trouble breathing;

  • liver problems - nausea, upper stomach pain, itching, tired feeling, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes); or

  • signs of an autoimmune disorde - -joint pain, tremors, weight loss, skin sores, mouth sores, hair loss, butterfly-shaped facial rash, numbness or tingling, blood or mucus in your stools, being more sensitive to hot or cold temperatures.

Common Plegridy side effects may include:

  • itching or skin redness where the injection was given;

  • flu symptoms (fever, chills, body aches);

  • muscle or joint pain;

  • headache; or

  • weakness.

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.

What other drugs will affect Plegridy?

Other drugs may interact with peginterferon beta-1a, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell each of your health care providers about all medicines you use now and any medicine you start or stop taking while using Plegridy.

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use Plegridy only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.