Pegasyspeginterferon alfa-2a
According to the FDA label: PEGASYS is an inducer of the innate immune response indicated for the treatment of Chronic Hepatitis C (CHC) ( 1.1 ) Adult Patients: In combination therapy with other hepatitis C virus drugs for adults with compensated liver disease. PEGASYS monotherapy is indicated only if patient has contraindication or significant intolerance to other HCV drugs.
53,689 adverse event reports submitted to the FDA (2003–2026)
Top Reported Adverse Events
The most frequently reported events in association with Pegasys in the FAERS database. These are events reported by patients taking this medication, not necessarily caused by it. A single report may include multiple events.
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Fatigue 9,259 reports
Extreme tiredness or lack of energy that does not improve with rest.
Full definition in the glossary → See all drugs reporting this event →Nausea 7,163 reports
The feeling of sickness in your stomach that often comes before vomiting.
Full definition in the glossary → See all drugs reporting this event →Anaemia 6,623 reports
A condition where there are too few healthy red blood cells to carry enough oxygen, often causing tiredness and paleness. Also spelled anemia in American English.
Full definition in the glossary → See all drugs reporting this event →Rash 4,878 reports
An area of irritated, red, or bumpy skin.
Full definition in the glossary → See all drugs reporting this event →Headache 4,454 reports
Pain in the head or upper neck.
Full definition in the glossary → See all drugs reporting this event →White Blood Cell Count Decreased 4,228 reports
A blood test result showing a low level of white blood cells, which help fight infection.
Full definition in the glossary →Pruritus 4,223 reports
Pyrexia 3,473 reports
The medical term for fever, meaning a raised body temperature.
Full definition in the glossary → See all drugs reporting this event →Diarrhoea 3,384 reports
Loose or watery bowel movements, often frequent. Also spelled diarrhea in American English.
Full definition in the glossary → See all drugs reporting this event →Vomiting 3,334 reports
Throwing up the contents of the stomach.
Full definition in the glossary → See all drugs reporting this event →Asthenia 3,148 reports
Physical weakness or lack of strength.
Full definition in the glossary →Insomnia 3,078 reports
Difficulty falling asleep or staying asleep.
Full definition in the glossary → See all drugs reporting this event →Dyspnoea 3,051 reports
Shortness of breath or difficulty breathing. Also spelled dyspnea in American English.
Full definition in the glossary → See all drugs reporting this event →Decreased Appetite 2,917 reports
Influenza Like Illness 2,737 reports
A set of symptoms resembling the flu, such as fever, aches, and tiredness, without a confirmed flu diagnosis.
Full definition in the glossary →
Ranked by frequency of reports, not severity. The most-reported event is not necessarily the most dangerous or the most common in patients taking this drug.
Who Is Reporting
Demographics of patients in FAERS reports that included this information. Not all reports include patient demographics.
By Sex
View reporter sex data as a table
| Sex | Reports |
|---|---|
| Male | 27,346 |
| Female | 23,331 |
| Unknown | 398 |
By Age Group
View age group data as a table
| Age group | Reports |
|---|---|
| 0-17 | 182 |
| 18-34 | 1,957 |
| 35-49 | 6,860 |
| 50-64 | 15,644 |
| 65-74 | 2,179 |
| 75+ | 293 |
This shows who filed reports, reflecting who takes this drug and who tends to report, not who is at greatest risk.
Reported Outcomes
Outcomes recorded in FAERS reports that included Pegasys. A single report may involve multiple reactions, each with a different outcome. These categories are defined by FDA reporting guidelines, not by PillSignal.
View outcome data as a table
| Outcome | Reports |
|---|---|
| Non-Serious | 30,826 |
| Other Serious | 13,947 |
| Hospitalization | 9,485 |
| Death | 1,797 |
| Life-Threatening | 921 |
| Disability | 658 |
Serious outcomes are far more likely to be reported than mild ones, so this overstates how often outcomes are serious. A recorded death does not mean the drug caused it.
Report Volume Over Time
Number of FAERS reports received per quarter for Pegasys. Changes in volume may reflect shifts in prescribing rates, media attention, or reporting behavior, not changes in the medication's safety profile.
View report trend as a table
| Year | Reports |
|---|---|
| 2003 | 4 |
| 2004 | 473 |
| 2005 | 1,118 |
| 2006 | 661 |
| 2007 | 655 |
| 2008 | 786 |
| 2009 | 973 |
| 2010 | 1,192 |
| 2011 | 1,492 |
| 2012 | 13,773 |
| 2013 | 8,523 |
| 2014 | 3,093 |
| 2015 | 17,300 |
| 2016 | 869 |
| 2017 | 546 |
| 2018 | 386 |
| 2019 | 326 |
| 2020 | 349 |
| 2021 | 249 |
| 2022 | 301 |
| 2023 | 193 |
| 2024 | 182 |
| 2025 | 211 |
| 2026 (partial) | 34 |
The steep increase around 2004 reflects the FDA's move to electronic submission, not a change in this drug's safety. Trends track reporting volume, not risk.
Medications commonly reported with Pegasys
In FDA adverse event reports that mention Pegasys, these medications appeared most often in the same report.
- Sofosbuvir (1,933 reports)
- Omeprazole (1,095 reports)
- Lisinopril (1,031 reports)
- Aspirin (784 reports)
- Alprazolam (748 reports)
This reflects co-occurrence in submitted reports, not evidence of drug interaction or combined risk. People often report several medications taken for the same condition or for unrelated reasons. Talk to a doctor or pharmacist about your specific medications.
Related Drugs
Other medications with similar adverse event profiles in FDA FAERS reports.
Data Source
This data is sourced from the FDA's Adverse Event Monitoring System (AEMS), formerly FAERS, via the OpenFDA API. PillSignal is not affiliated with the FDA.
View this data on the FDA website →Data last updated: June 2026