Peginterferon Beta-1a: uses, dosing, side effects & brands
Peginterferon Beta-1a is a medicine sold in the U.S. under one brand, for multiple sclerosis. Below: what the FDA label says, every product that contains it, what the pills look like, and its recall record.
Key facts
- Treats (across its forms)
- Multiple Sclerosis
- Available as
- Injectable · Kit
- Sold as
- Plegridy
- Prescription?
- Prescription only
- Generic available?
- Not in our catalog
How peginterferon beta-1a is dosed
From the FDA label for Plegridy (application BLA125499). Other peginterferon beta-1a products — different forms, different strengths — are dosed differently. Follow the label for the one you were prescribed.
For subcutaneous or intramuscular use only ( 2.1 ) Recommended dose: 125 micrograms every 14 days ( 2.1 ) PLEGRIDY dose should be titrated, starting with 63 micrograms on day 1, 94 micrograms on day 15, and 125 micrograms (full dose) on day 29 ( 2.1 ) A healthcare professional should train patients in the proper technique for self-administering subcutaneous injections using the prefilled pen or syringe or intramuscular injections using the prefilled syringe ( 2.2 ) Analgesics and/or antipyretics on treatment days may help ameliorate flu-like symptoms ( 2.3 ) 2.1 Dosing Information PLEGRIDY may only be administered subcutaneously (SC) or intramuscularly (IM). Recommended Maintenance Dosage After initial titration (see Table 1 and Table 2 ), the recommended dosage of PLEGRIDY is 125 micrograms injected every 14 days. For subcutaneous injection: Patients may rotate injection sites between the abdomen, back of the upper arm, or thigh. For intramuscular injection: Patients may rotate injection sites between the left and right thighs. Treatment Initiation Dose titration at the initiation of treatment may help to ameliorate flu-like symptoms that can occur at treatment initiation with interferons. Prophylactic and concurrent use of analgesics and/or antipyretics may prevent or ameliorate flu-like symptoms sometimes experienced during treatment with PLEGRIDY. Switching between the…
Peginterferon Beta-1a side effects
The following serious adverse reactions are discussed in more detail in other sections of labeling: Hepatic Injury [see Warnings and Precautions ( 5.1 )] Depression and Suicide [see Warnings and Precautions ( 5.2 )] Anaphylaxis and Other Allergic Reactions [see Warnings and Precautions ( 5.3 )] Injection Site Reactions Including Necrosis [see Warnings and Precautions ( 5.4 )] Congestive Heart Failure [see Warnings and Precautions (Section 5.5 )] Decreased Peripheral Blood Counts [see Warnings and Precautions ( 5.6 )] Thrombotic Microangiopathy [see Warnings and Precautions ( 5.7 )] Pulmonary Arterial Hypertension [see Warnings and Precautions ( 5.8 )] Autoimmune Disorders [see Warnings and Precautions ( 5.9 )] Seizures [see Warnings and Precautions ( 5.10 )] The most common adverse reactions in clinical trials of subcutaneous PLEGRIDY (incidence ≥10% and at least 2% more frequent on PLEGRIDY than on placebo) were injection site erythema, influenza-like illness, pyrexia, headache, myalgia, chills, injection site pain, asthenia, injection site pruritus, and arthralgia ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Biogen at 1-800-456-2255 or FDA at 1-800-FDA-1088 or http://www.fda.gov/medwatch. 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of PLEGRIDY cannot be…
Who shouldn’t take peginterferon beta-1a
PLEGRIDY is contraindicated in patients with a history of hypersensitivity to natural or recombinant interferon beta or peginterferon, or any other component of PLEGRIDY [see Warnings and Precautions ( 5.3 )] . History of hypersensitivity to natural or recombinant interferon beta or peginterferon, or any other component of PLEGRIDY ( 4 )
Every peginterferon beta-1a product we track (1)
Same active ingredient — different manufacturer, form, price and FDA recall record. That last one is what our independent score measures.
Only one: Plegridy.
What people report to the FDA about peginterferon beta-1a
The FDA Adverse Event Reporting System (FAERS) collects reports from patients and clinicians. It holds 64 reports naming peginterferon beta-1a, and the FDA flagged 89% of those reports as serious. The effects reported most often — leaving out reports about overdose, misuse or the condition being treated, which dominate the raw list for common medicines:
- multiple sclerosis relapse18 reports
- dizziness10 reports
- nausea10 reports
- anaemia6 reports
- general physical health deterioration6 reports
- menorrhagia5 reports
- therapy non-responder4 reports
- covid-193 reports
Read these as a signal, not a rate. A report does not mean peginterferon beta-1a caused the effect — anyone can file one, and many describe people taking several medicines for several conditions. Crucially there is no denominator: FAERS does not record how many people took the drug, so these counts cannot be turned into “X% of patients” — a bigger number often just means a more widely used or more talked-about drug. Duplicates exist, and publicity drives reporting. For what is actually established, read the FDA label section above.
Source: openFDA drug/event (FAERS), retrieved July 25, 2026.
Related calculators
Frequently asked questions
What is peginterferon beta-1a?
Plegridy (Peginterferon Beta-1a) is a medication used to treat Multiple Sclerosis.
Can you take peginterferon beta-1a with other medicines?
It depends on the medicine. We check it against the FDA labels rather than guessing: our interaction checker searches each drug's own label for the other and quotes what it says, naming the section it came from. Run peginterferon beta-1a against whatever else you take — and remember that a label not naming a drug is not the same as that combination being safe.
What forms does peginterferon beta-1a come in?
Across the brands we track, peginterferon beta-1a is currently marketed as injectable and kit, per the FDA's National Drug Code Directory. Each form is dosed differently — follow the label for the exact product you were prescribed.
Is there a generic peginterferon beta-1a?
We do not currently list a generic-labelled peginterferon beta-1a product. That does not always mean none exists — it means none appears under a generic name in the FDA data we track. Ask your pharmacist.
Cite this page
- APA
- pharmaranks. (2026, July 24). Peginterferon Beta-1a: uses, dosing, side effects & brands. https://pharmaranks.com/drugs/peginterferon-beta-1a
- MLA
- “Peginterferon Beta-1a: uses, dosing, side effects & brands.” pharmaranks, 24 July 2026, https://pharmaranks.com/drugs/peginterferon-beta-1a.
We summarise public FDA and NIH sources — for a clinical claim, cite the primary source we link to as well.
Sources: FDA openFDA drug label, National Drug Code Directory, and Enforcement (recall) database. This page reproduces public FDA data and is not medical advice. Dosing is set by your prescriber.
Read the full FDA label for peginterferon beta-1a on DailyMed (NIH) ↗.