Generic name
Interferon beta-1a: adverse event reports filed with FDA
764 reports list it as a suspect or interacting product, 2005–2026. Class: Interferon beta.
- 764
- reports as suspect product
- 0% of all reports · about 37 a year
- 62
- reports, 12 months to June 2026
- 62 in the 12 months before
- 89.5%
- marked serious by the reporter
- 57.9% across the class
- 6.3%
- record death among outcomes, as reported
- 48 reports · not verified by FDA
Between August 2005 and June 2026, 764 adverse event reports received by FDA list interferon beta-1a, a generic name as a suspect or interacting product. Reports that mention it only as a concomitant medication (204) are left out of every figure here.
In the 12 months to June 2026, 62 reports listed it, close to the 62 of the 12 months before. FDA releases FAERS data quarterly, so the newest months are incomplete and grow in later releases. Over its reporting history that is about 37 reports a year and 0% of the 20,646,523 reports in the database, and 0.4% of the reports for the interferon beta class. How many people take it is not in the data, so a count is not a rate of occurrence.
The reactions recorded most often are multiple sclerosis relapse (6.7%), maternal exposure during pregnancy (5.4%) and off label use (5.1%). A report can list several reactions, so shares add to more than 100%; 303 different terms appear across these reports. Multiple sclerosis relapse is recorded in 6.7% of these reports, about the same share as in the median interferon beta drug (7.9%).
89.5% of the reports are marked serious by the reporter (57.9% across the class); 6.3% record death among the outcomes and 29.2% record hospitalisation, as reported. 47% of the reports came from consumers, and the largest patient age group is 18 to 44 (30.9%). FDA states that "a causal relationship cannot be established between product and reactions listed in a report" and that for any given report "there is no certainty that a suspected drug caused the event."
Reports by month, five years
Reports by the month FDA received them. FDA releases FAERS data quarterly, so the newest months are incomplete and grow in later releases.
By year received
2026 covers reports received through June 2026 only.
Reactions recorded in the reports
share of Interferon beta-1a reports recording the termmedian drug in interferon beta
- Multiple sclerosis relapsea flare of multiple sclerosis6.7%51
- Maternal exposure during pregnancythe mother took the medicine during pregnancy5.4%41
- Off label useused for a purpose or in a way not on the label5.1%39
- Drug ineffectivethe medicine did not work as expected4.3%33
- Foetal exposure during pregnancythe unborn baby was exposed to the medicine2.9%22
- Live birth2.9%22
- Encephalopathy2.6%20
- Falla fall2.4%18
- Multiple sclerosis2.4%18
- Painpain, site not specified2.4%18
- Confusional stateconfusion2.2%17
- Headachehead pain2%15
- Pyrexiafever2%15
- Covid-19COVID-19 infection1.8%14
- Influenza like illnessflu-like symptoms1.8%14
- Muscular weaknessmuscle weakness1.8%14
- Pneumonialung infection1.8%14
- Anxietyanxiety1.7%13
- Injection site painpain where the injection was given1.7%13
- Myoclonus1.7%13
- Nauseafeeling sick1.7%13
- Diabetes mellitusdiabetes1.6%12
- Gait disturbancedifficulty walking1.6%12
- Hypertensionhigh blood pressure1.6%12
- Hypoaesthesianumbness1.6%12
- Malaisegeneral feeling of being unwell1.6%12
- Secondary progressive multiple sclerosis1.6%12
- Dyspnoeashortness of breath1.4%11
- Premature delivery1.4%11
Top 30 of 303 MedDRA preferred terms recorded across these reports, with a plain-language gloss where one is available. One report can record several terms. The hollow bar is the median share across the 5 drugs in the interferon beta class; it describes the reports, not the patients. FDA states that adverse event reports "represent a small percentage of total usage numbers of a product", that "common products may have a higher number of adverse events due to the higher total number of people using the product", and that the data "by themselves are not an indicator of the safety profile of the drug or biologic."
Outcomes recorded
Outcome flags as the reporter set them; a report can carry several, and "other serious" is FDA's own category for serious reports outside the named outcomes. Grey bar: all 177,168 reports in the class. FDA has not verified any outcome and states that the reports "cannot be used to estimate the incidence of these events."
Patients and reporters
Patient age
Patient sex
Who reported
Age and sex as stated in the report; the reporter's qualification is the primary source recorded by FDA. 25.3% of reports give the United States as the country of the event or reporter.
Reason for use recorded
| Indication as recorded (MedDRA) | Reports | Share |
|---|---|---|
| Multiple sclerosis | 453 | 59.3% |
| Relapsing-remitting multiple sclerosis | 122 | 16% |
| Covid-19 | 19 | 2.5% |
| Coronavirus infection | 4 | 0.5% |
| Relapsing multiple sclerosis | 3 | 0.4% |
| Acute respiratory distress syndrome | 2 | 0.3% |
The indication field is filled in by the reporter and is often blank; shares are of all 764 reports.
In context
| Measure | Interferon beta-1a | Interferon beta | All reports |
|---|---|---|---|
| Reports as suspect product | 764 | 177,168 | 20,646,523 |
| Share of that pool | — | 0.4% | 0% |
| Reports, latest 12 months | 62 | — | 1,332,454 |
| Marked serious | 89.5% | 57.9% | 57.4% |
| Death recorded among outcomes, per 1,000 reports | 63 | 55 | 91 |
| Hospitalisation recorded, per 1,000 reports | 292 | 346 | 213 |
| Consumer-filed share | 47% | 68.2% | 45.8% |
| Top term, share of reports | Multiple sclerosis relapse 6.7% | median 7.9% | 0.3% |
Shares are of reports, not of patients treated. The number of people taking a product is not in the data, so none of these figures is a rate, and differences between columns reflect who takes a product, who reports and how long it has been sold. FDA states that adverse event reports "represent a small percentage of total usage numbers of a product", that "common products may have a higher number of adverse events due to the higher total number of people using the product", and that the data "by themselves are not an indicator of the safety profile of the drug or biologic."
Other drugs in the interferon beta class
| Drug | Name type | Reports | Latest 12 months | Marked serious |
|---|---|---|---|---|
| Avonex | brand | 116,302 | 837 | 51.1% |
| Rebif | brand | 43,252 | 456 | 79.6% |
| Plegridy | brand | 12,695 | 418 | 42.9% |
| Avonex Pen | brand | 4,155 | 0 | 64.1% |
Ordered by report count for navigation only. FDA states that adverse event reports "represent a small percentage of total usage numbers of a product", that "common products may have a higher number of adverse events due to the higher total number of people using the product", and that the data "by themselves are not an indicator of the safety profile of the drug or biologic." A brand and its generic are separate rows because reporters name them separately.
Questions about Interferon beta-1a reports
How many adverse event reports has FDA received for Interferon beta-1a?
764 reports list Interferon beta-1a as a suspect or interacting product in the openFDA FAERS release of 28 Sep 2026, covering reports received through June 2026. 62 of them arrived in the latest 12 months. Another 204 list it only as a concomitant medication.
What reactions are recorded in Interferon beta-1a reports?
multiple sclerosis relapse (6.7%), maternal exposure during pregnancy (5.4%), off label use (5.1%), drug ineffective (4.3%) and foetal exposure during pregnancy (2.9%). These are MedDRA preferred terms coded from what the reporter described; a report can list several, and a term's presence is not a finding that Interferon beta-1a was responsible.
How serious are the reports?
89.5% are marked serious by the reporter. Among the outcomes recorded, 6.3% of reports include death and 29.2% include hospitalisation. FDA has not verified these outcomes and states that the reports "cannot be used to estimate the incidence" of the events.
Who files these reports?
consumer or non-health professional (47%), other health professional (25.4%) and physician (23.2%). Most reports reach FDA through the manufacturer, which must forward reports it receives.
Are reports for Interferon beta-1a rising?
62 reports in the 12 months to June 2026, close to the 62 of the 12 months before. FDA releases FAERS data quarterly, so the newest months are incomplete and grow in later releases. Counts also move with how many people take a product, its time on the market and publicity.
Do these reports show that Interferon beta-1a was responsible for these reactions?
No. FDA states that "a causal relationship cannot be established between product and reactions listed in a report" and that for any given report "there is no certainty that a suspected drug caused the event." The reaction may relate to the condition being treated, to other medicines, or to something else.
Is this a list of the side effects of Interferon beta-1a?
No. It is a count of what was reported to FDA. The adverse reactions observed in clinical studies are printed on the FDA-approved label, which a pharmacist or clinician can go through with you.
How do I report an adverse event?
Consumers and health professionals can report to FDA through MedWatch (Form FDA 3500 online, or 1-800-FDA-1088), or to the manufacturer, which must pass reports on. See the guide on how to report.
Where this comes from. Counts are built from the openFDA Drug Adverse Event (FAERS) bulk export released 28 Sep 2026, which holds reports FDA received through 30 Jun 2026. Drug names are as reported, resolved to the brand or generic name on the FDA label where openFDA's harmonisation matched them; classes are the pharmacologic class (EPC) from the label and the National Drug Code Directory of 17 Sep 2026. A report counts here when it lists Interferon beta-1a as a suspect or interacting product; reports listing it only as a concomitant medication (204) are excluded. No report narrative, lot number, patient detail or reporter identity is published. See the methodology and sources; FDA's record is authoritative, and corrections are handled within five working days.
Drug data (FAERS) through 30 Jun 2026; device data (MAUDE) through 31 Aug 2026. Not medical advice.