What the label lists and what reports show
Ropeginterferon alfa 2b side effects
Ropeginterferon alfa 2b's FDA label: “The most common adverse reactions reported in >20% of patients were transaminase elevations, anemia, pyrexia, beta 2 microglobulin urine increased, bacterial infection, pruritus, and weight decreased.” FAERS holds 1,776 reports naming it through July 30, 2026; the reaction reported most often, leaving out the conditions it is used for, product-use terms and outcomes, is fatigue (341 reports).
- No generic listed
- Boxed warning
Check it at the source: the ropeginterferon alfa 2b FDA label on DailyMed (effective August 25, 2026); the FDA FAERS public dashboard.
What does the patient leaflet say about side effects?
From the patient leaflet: What are the possible side effects of BESREMi?BESREMi can cause serious side effects including: • See “What is the most important information I should know about BESREMi?” • Decreased blood cell counts and bleeding problems. BESREMi can cause decreased blood cell counts, including decreased platelets, red blood cells, or white blood cells, that can sometimes be severe. If your blood cell counts are low, you can develop anemia, serious infections, or have problems with bleeding or bruising. Your healthcare provider will monitor you for signs or symptoms of infection or bleeding. […]
Source: FDA drug label, PharmaEssentia USA, effective August 25, 2026 (SPL set 9583405d-53a0-49dc-88eb-5e6384ebabcb), via openFDA; the full label on DailyMed
What does the label list?
From the label: adverse reactionsThe most common adverse reactions reported in >20% of patients were transaminase elevations, anemia, pyrexia, beta 2 microglobulin urine increased, bacterial infection, pruritus, and weight decreased.
Table 5 Adverse Reactions in >10% of Patients with Polycythemia Vera in the PEGINVERA Study Over 7.5 Years.
| Adverse Reactions* | *Adverse Reactions defined as all treatment emergent adverse events Grouped Term Definitions a Includes pyrexia, chills, and influenza-like illness. b Includes asthenia, malaise, and fatigue. c Includes pharyngitis and nasopharyngitis. d Includes musculoskeletal pain, back pain, pain in extremity, bone pain, flank pain, and… e Includes headache, migraine, and head pain. f Includes night sweats and hyperhidrosis. g Includes upper respiratory tract infection, rhinitis, bronchitis, and respiratory tract… h Includes abdominal pain upper, abdominal pain lower, and abdominal pain. i Includes insomnia, sleep disorder, and abnormal dreams. j Includes peripheral edema and generalized edema. k Includes hypertension and hypertensive crisis. l Includes rash, maculopapular rash, and pruritic rash. m Includes transaminase increase, hepatic enzyme increase, GGT increase, AST increase,… Clinically relevant adverse reactions in <10% of patients include: Cardiovascular System: Atrial fibrillation BESREMi N=51 % |
|---|---|
| Influenza-like illness a | 59 |
| Arthralgia | 47 |
| Fatigue b | 47 |
| Pruritus | 45 |
| Nasopharyngitis c | 43 |
| Musculoskeletal pain d | 41 |
| Headache e | 39 |
| Diarrhea | 33 |
| Hyperhidrosis f | 29 |
| Nausea | 28 |
| Upper respiratory tract infection g | 27 |
| Local administration site reactions | 26 |
| Dizziness | 22 |
| Abdominal pain h | 20 |
| Depression | 20 |
| Sleep disorder i | 20 |
| Leukopenia | 18 |
| Decreased appetite | 18 |
| Alopecia | 16 |
| Edema j | 16 |
| Hypertension k | 16 |
| Muscle spasms | 16 |
| Neutropenia | 16 |
| Rash l | 16 |
| Transaminase elevations m | 16 |
Rows and numbers as the label prints them, under its own column headings (the first rows of a longer table where it runs on). A reaction in a trial table is not necessarily caused by the medicine, and trials differ from everyday use.
From the label: adverse reactions, continuedThe following clinically significant adverse reactions are described elsewhere in the labeling. • Depression and Suicide [see Warnings and Precautions ( 5.1 )] • Endocrine Toxicity [see Warnings and Precautions ( 5.2 )] • Cardiovascular Toxicity [see Warnings and Precautions ( 5.3 )] • Hematologic and Hemorrhagic Disorders [see Warnings and Precautions ( 5.4 )] • Hypersensitivity Reactions [see Warnings and Precautions ( 5.5 )] • Pancreatitis [see Warnings and Precautions ( 5.6 )] • Colitis [see Warnings and Precautions ( 5.7 )] • Pulmonary Toxicity [see Warnings and Precautions ( 5.8 )] • Ophthalmologic Toxicity [see Warnings and Precautions ( 5.9 )] • Hyperlipidemia [see Warnings and Precautions ( 5.10 )] • Hepatotoxicity [see Warnings and Precautions ( 5.11 )] • Renal Toxicity [see Warnings and Precautions ( 5.12 )] • Dental and Periodontal Toxicity [see Warnings and Precautions ( 5.13 )] • Dermatologic Toxicity [see Warnings and Precautions ( 5.14 )] • Driving and Operating Machinery [see Warnings and Precautions ( 5.15 )] • Embryo-Fetal Toxicity [see Warnings and Precautions ( 5.16 )] • Essential thrombocythemia: The most common adverse reactions reported in >20% of patients were transaminase elevations, anemia, pyrexia, beta 2 microglobulin urine increased, bacterial infection, pruritus, and weight decreased. …
Source: FDA drug label, PharmaEssentia USA, effective August 25, 2026 (SPL set 9583405d-53a0-49dc-88eb-5e6384ebabcb), via openFDA; the full label on DailyMed
What do FAERS reports show?
1,776 reports list ropeginterferon alfa 2b among the medicines taken, each a report of something that happened, not proof the medicine caused it; 29 are coded as a death and 166 as a hospital stay. Counts follow how widely a medicine is used and watched, and they are not a measure of how risky it is. Of the 21 reactions below, 14 are named by the same term (in US spelling) in the label's adverse reactions, warnings or patient leaflet; a reaction the label does not name may still be there under another word, and a report does not show that the medicine caused it.
Reports received each year
The 25 most reported reactions
Source: FDA Adverse Event Reporting System (FAERS) via openFDA, reports through July 30, 2026; reactions as MedDRA preferred terms
What next?
- Ropeginterferon alfa 2b: the full record
- label, generics, price, shortages, recalls
- Report a side effect to the FDA
- MedWatch
- Side effects hub
- the most reported medicines and reactions