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Ofatumumab Side Effects

The most commonly reported side effects of ofatumumab include fatigue, headache, and pyrexia, based on 32,609 FDA adverse event reports from 2008 to 2025. 3.7% of reports found the drug to be ineffective.

Ofatumumab side effects

Percentages show how often each reaction appears relative to total reports for ofatumumab.

1
Fatigue16.5%5,370
2
Headache13.9%4,524
3
Pyrexia10.7%3,494
4
Pain10.7%3,476
5
Chills10.5%3,433
6
Influenza Like Illness8.5%2,787
7
Nausea5.4%1,757
8
Multiple Sclerosis Relapse5.0%1,616
9
Covid-194.6%1,505
10
Asthenia4.5%1,457
11
Gait Disturbance4.3%1,396
12
Multiple Sclerosis4.2%1,372
13
Hypoaesthesia4.2%1,367
14
Feeling Abnormal4.1%1,343
15
Malaise4.1%1,321

These are voluntary reports and do not establish that ofatumumab caused these reactions.

Report severity

43.7%Serious14,235 reports
14.1%Hospitalizations4,582 reports
2.8%Fatal908 reports

Seriousness is determined by the reporter, not by OpenClaim.

Ofatumumab drug interactions

Other drugs that appear in adverse event reports alongside ofatumumab. Drugs flagged as a suspected cause appear in the first column. Drugs taken at the same time but not suspected appear in the second.

Also suspected

1
Rituximab2.3%736
2
Bendamustine-hydrochloride2.2%717
3
Dexamethasone1.5%475
4
Ibrutinib1.4%450
5
Etoposide1.3%411
6
Methotrexate1.2%403
7
Idelalisib1.1%372
8
Cyclophosphamide1.1%362
9
Ifosfamide1.1%359
10
Ocrelizumab1.1%356
11
Obinutuzumab1.1%349
12
Venetoclax1.1%347
13
Chlorambucil1.0%336
14
Fingolimod1.0%327
15
Carboplatin1.0%311

Taken alongside

1
Ergocalciferol7.0%2,280
2
Acetaminophen4.8%1,571
3
Gabapentin3.3%1,081
4
Baclofen2.8%902
5
Cyanocobalamin2.5%810
6
Ibuprofen2.2%719
7
Allopurinol1.9%616
8
Levothyroxine-sodium1.9%613
9
Aspirin1.7%547
10
Omeprazole1.5%483
11
Metoclopramide-hydrochloride1.4%458
12
Amoxicillin1.3%436
13
Atorvastatin-calcium1.3%426
14
Ascorbic-acid1.3%420
15
Hydrocortisone1.3%409

Co-occurrence in adverse event reports does not establish a drug interaction. Patients often take multiple medications, and these lists reflect prescribing patterns rather than causal relationships. Consult a healthcare provider about potential drug interactions.

Who reports ofatumumab side effects

66.0% of ofatumumab adverse event reports involve female patients and 23.8% involve male patients. The largest age group is adult at 86%. These figures reflect who reports side effects, not underlying risk.

Sex

Female66.0%
Male23.8%
Unknown10.2%

Age group

< 20.4%
2–110.4%
12–170.3%
18–6485.6%
65+13.4%

What is ofatumumab used for

Conditions and purposes for which patients were taking ofatumumab when the adverse event was reported.

Acquired HaemophiliaAcute Lymphocytic LeukaemiaAutoimmune EncephalopathyAbdominal DiscomfortAcute Graft Versus Host Disease In SkinAcute Lymphocytic LeukaemiaAnti-srp Antibody PositiveArthritisAsthmaAutoimmune DisorderB-cell LymphomaB-cell Lymphoma RecurrentB-cell Lymphoma RefractoryB-cell Lymphoma Stage IiB-cell Small Lymphocytic Lymphoma

Showing 15 of 268 indications

Ofatumumab brand names and reporting trend

Ofatumumab is sold under the brand name Arzerra.

Brand names

Arzerra4,633

Quarterly reports (20082025)

2010201520202025

An upward trend reflects increased FAERS reporting overall, not necessarily increased risk.

Taking ofatumumab with another medication?

Ask OpenClaim about your specific drug combination. Get a sourced report using FDA data, drug labels, and medical literature.