Reported Reactions

Drugs › CD20-directed cytolytic antibody

Generic name

Ofatumumab: adverse event reports filed with FDA

2,942 reports list it as a suspect or interacting product, 2009–2026. Class: CD20-directed cytolytic antibody. Also reported as Ofatumumab Injection, Ofatumumab Solution For Injection.

2,942
reports as suspect product
0% of all reports · about 172 a year
97
reports, 12 months to June 2026
166 in the 12 months before
97.9%
marked serious by the reporter
77% across the class
13.5%
record death among outcomes, as reported
397 reports · not verified by FDA

2,942 adverse event reports received by FDA list ofatumumab, a generic name as a suspect or interacting product, from June 2009 to June 2026. A further 276 reports list it only as a concomitant medication, and those are not counted in the figures on this page.

In the 12 months to June 2026, 97 reports listed it, down 42% from 166 in 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 172 reports a year and 0% of the 20,646,523 reports in the database, and 0.9% of the reports for the CD20-directed cytolytic antibody class. How many people take it is not in the data, so a count is not a rate of occurrence.

Reporters most often recorded febrile neutropenia (16.5%), neutropenia (11.9%) and anaemia (10.5%). A report can list several reactions, so shares add to more than 100%; 510 different terms appear across these reports. Febrile neutropenia is recorded in 16.5% of these reports, a larger share than in the median CD20-directed cytolytic antibody drug (1%).

97.9% of the reports are marked serious by the reporter (77% across the class); 13.5% record death among the outcomes and 54.7% record hospitalisation, as reported. 58% of the reports came from physicians, and the largest patient age group is 45 to 64 (21%). 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

04080Jul 2021: 5Aug 2021: 9Sep 2021: 7Oct 2021: 4Nov 2021: 8Dec 2021: 142022Jan 2022: 20Feb 2022: 58Mar 2022: 80Apr 2022: 37May 2022: 42Jun 2022: 5Jul 2022: 12Aug 2022: 8Sep 2022: 14Oct 2022: 8Nov 2022: 0Dec 2022: 42023Jan 2023: 9Feb 2023: 5Mar 2023: 7Apr 2023: 13May 2023: 9Jun 2023: 8Jul 2023: 8Aug 2023: 6Sep 2023: 10Oct 2023: 15Nov 2023: 26Dec 2023: 142024Jan 2024: 17Feb 2024: 20Mar 2024: 19Apr 2024: 28May 2024: 42Jun 2024: 17Jul 2024: 20Aug 2024: 18Sep 2024: 19Oct 2024: 20Nov 2024: 7Dec 2024: 142025Jan 2025: 11Feb 2025: 11Mar 2025: 17Apr 2025: 10May 2025: 8Jun 2025: 11Jul 2025: 13Aug 2025: 6Sep 2025: 8Oct 2025: 15Nov 2025: 18Dec 2025: 92026Jan 2026: 7Feb 2026: 3Mar 2026: 7Apr 2026: 7May 2026: 0Jun 2026: 4

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

01613222009: 1020092010: 1012011: 14420112012: 2322013: 28420132014: 2722015: 32220152016: 2252017: 12820172018: 1342019: 8520192020: 1062021: 7520212022: 2882023: 13020232024: 2412025: 13720252026: 28

2026 covers reports received through June 2026 only.

Reactions recorded in the reports

share of Ofatumumab reports recording the termmedian drug in cd20-directed cytolytic antibody

  1. Febrile neutropeniafever with low white blood cells16.5%485
  2. Neutropenialow neutrophils, a type of white blood cell11.9%349
  3. Anaemialow red blood cells10.5%309
  4. Thrombocytopenialow platelets10.3%302
  5. Infectionan infection, type not specified10.2%300
  6. Atrial fibrillationan irregular heart rhythm9.8%287
  7. Haemorrhagebleeding8.9%263
  8. Cytopenia8.7%257
  9. Pyrexiafever7.7%226
  10. Disease progressionthe disease advanced6.5%191
  11. Pneumonialung infection6.1%178
  12. Fatiguetiredness3.6%105
  13. Off label useused for a purpose or in a way not on the label3.1%90
  14. Headachehead pain2.7%80
  15. Vomitingbeing sick2.6%76
  16. Sepsisa severe body-wide response to infection2.5%74
  17. Nauseafeeling sick2.2%65
  18. Dyspnoeashortness of breath2.1%61
  19. Astheniaweakness or lack of energy1.9%57
  20. Diarrhoealoose or frequent stools1.8%54
  21. Infusion related reactiona reaction during or soon after an infusion1.8%54
  22. Drug ineffectivethe medicine did not work as expected1.8%52
  23. Rashskin rash1.8%52
  24. Dizzinesslight-headedness or unsteadiness1.6%48
  25. Malaisegeneral feeling of being unwell1.6%47
  26. Product use in unapproved indicationused for a purpose not on the label1.6%47

Top 30 of 510 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 12 drugs in the cd20-directed cytolytic antibody 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

Death13.5%397
Life-threatening6.5%190
Hospitalisation (initial or prolonged)54.7%1,609
Disability1.2%36
Congenital anomaly0%1
Other serious52.5%1,544
Not serious2.1%63

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 316,120 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

Under 20.1%2
2 to 111%29
12 to 171%29
18 to 449.6%283
45 to 6421%617
65 to 7417.8%523
75 and over17.7%520
Age not given31.9%939

Patient sex

Female34.3%1,009
Male46.1%1,356
Not given19.6%577

Who reported

Physician58%1,706
Pharmacist0.7%20
Other health professional26.2%770
Lawyer0%0
Consumer or non-health professional13.4%394
Not given1.8%52

Age and sex as stated in the report; the reporter's qualification is the primary source recorded by FDA. 20.6% of reports give the United States as the country of the event or reporter.

Reason for use recorded

Indication as recorded (MedDRA)ReportsShare
Chronic lymphocytic leukaemia1,16039.4%
Multiple sclerosis1846.3%
Central nervous system lymphoma1003.4%
B-cell lymphoma913.1%
Relapsing-remitting multiple sclerosis893%
Diffuse large b-cell lymphoma recurrent862.9%

The indication field is filled in by the reporter and is often blank; shares are of all 2,942 reports.

Drugs most often listed in the same reports

Drug (any role in the report)ReportsShare of Ofatumumab reports
Allopurinol55118.7%
Rituximab50617.2%
Bendamustine49116.7%
Aciclovir45215.4%
Paracetamol44515.1%
Dexamethasone43314.7%
Metoclopramide42214.3%
Etoposide34111.6%
Cotrimoxazole33011.2%
Cyclophosphamide32711.1%

Other products listed in reports where Ofatumumab is a suspect product, whatever their own role. Co-listing means the two were recorded together; it says nothing about either product's part in the event. Only the 2,500 most-reported names are counted here.

In context

MeasureOfatumumabCD20-directed cytolytic antibodyAll reports
Reports as suspect product2,942316,12020,646,523
Share of that pool—0.9%0%
Reports, latest 12 months97—1,332,454
Marked serious97.9%77%57.4%
Death recorded among outcomes, per 1,000 reports13512591
Hospitalisation recorded, per 1,000 reports547274213
Consumer-filed share13.4%28%45.8%
Top term, share of reportsFebrile neutropenia 16.5%median 1%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 cd20-directed cytolytic antibody class

DrugName typeReportsLatest 12 monthsMarked serious
Rituximabgeneric155,57815,06895.8%
Ocrevusbrand52,2583,25349.1%
Rituxanbrand41,51579270.9%
Kesimptabrand29,2572,65838.3%
Obinutuzumabgeneric9,2681,03794.4%
Ocrelizumabgeneric6,93260063.9%
Gazyvabrand5,29451265.9%
Ruxiencebrand4,72380791.1%
Truximabrand4,63040072.3%
Ublituximabgeneric2,5101,29022.1%
Briumvibrand1,21341820.9%

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 Ofatumumab reports

How many adverse event reports has FDA received for Ofatumumab?

2,942 reports list Ofatumumab as a suspect or interacting product in the openFDA FAERS release of 28 Sep 2026, covering reports received through June 2026. 97 of them arrived in the latest 12 months. Another 276 list it only as a concomitant medication.

What reactions are recorded in Ofatumumab reports?

febrile neutropenia (16.5%), neutropenia (11.9%), anaemia (10.5%), thrombocytopenia (10.3%) and infection (10.2%). 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 Ofatumumab was responsible.

How serious are the reports?

97.9% are marked serious by the reporter. Among the outcomes recorded, 13.5% of reports include death and 54.7% 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?

physician (58%), other health professional (26.2%) and consumer or non-health professional (13.4%). Most reports reach FDA through the manufacturer, which must forward reports it receives.

Are reports for Ofatumumab rising?

97 reports in the 12 months to June 2026, down 42% from 166 in 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 Ofatumumab 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 Ofatumumab?

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 Ofatumumab as a suspect or interacting product; reports listing it only as a concomitant medication (276) 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.