What the label lists and what reports show
Epcoritamab side effects
Epcoritamab's FDA label: “The most common (≥ 20%) adverse reactions are CRS, injection site reactions, fatigue, musculoskeletal pain, fever, diarrhea, COVID-19, rash and abdominal pain.” FAERS holds 1,272 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 cytokine release syndrome (450 reports).
- No generic listed
- Boxed warning
Check it at the source: the epcoritamab FDA label on DailyMed (effective June 22, 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 EPKINLY?EPKINLY can cause serious side effects, including: See " What is the most important information I should know about EPKINLY? " Infections. EPKINLY can cause serious infections that may lead to death. Your healthcare provider will check you for signs and symptoms of infection before and during treatment with EPKINLY. Your healthcare provider should prescribe medicines before you start treatment to help prevent infection and treat you as needed if you develop an infection during treatment with EPKINLY. Tell your healthcare provider right away if you develop any signs or symptoms of infection during treatment with EPKINLY, including: fever of 100.4°F (38°C) or higher cough chest pain tiredness shortness of breath painful rash sore throat pain during urination feeling weak or generally unwell confusion Low blood cell counts. […]
Source: FDA drug label, Genmab US, Inc., effective June 22, 2026 (SPL set d7836711-b677-412d-bf2d-0f7c8444103a), via openFDA; the full label on DailyMed
What does the label list?
From the label: adverse reactionsThe most common (≥ 20%) adverse reactions are CRS, injection site reactions, fatigue, musculoskeletal pain, fever, diarrhea, COVID-19, rash and abdominal pain.
Table 15: Adverse Reactions (≥ 10%) in Patients with Relapsed or Refractory FL Who Received EPKINLY as Monotherapy in EPCORE NHL-1
| Reaction | Adverse Reaction Adverse reactions were graded based on CTCAE Version 5.0. All Grades (%) | EPKINLY Grade 3 or 4 (%) |
|---|---|---|
| Cytokine release syndrome CRS was graded using ASTCT consensus criteria (Lee et al.,… | 49 | 0 |
| Injection site reactions Includes related grouped terms. | 58 | 0 |
| Fatigue | 37 | 5 Only Grade 3 adverse reactions occurred. |
| Pyrexia | 26 | 2 |
| Edema | 17 | 0 |
| COVID-19 COVID-19 includes COVID-19, COVID-19 pneumonia, SARS-CoV-2 test positive. | 40 | 19 |
| Upper respiratory tract infection Upper respiratory tract infection includes preferred… | 29 | 2 |
| Pneumonia Pneumonia includes preferred terms with pneumonia, bronchopulmonary… | 17 | 13 |
| Urinary tract infection | 13 | 5 |
| Herpesvirus infection Herpesvirus infection includes herpes simplex, herpes simplex… | 12 | 1.6 |
| Musculoskeletal pain | 28 | 0.8 |
| Arthralgia | 14 | 0.8 |
| Rash | 28 | 0 |
| Diarrhea | 26 | 1.6 |
| Nausea | 17 | 0 |
| Abdominal pain | 17 | 0.8 |
| Constipation | 16 | 0 |
| Mucositis Mucositis includes aphthous ulcer, mouth ulceration, mucosal inflammation, oral… | 12 | 0 |
| Cough | 20 | 0 |
| Dyspnea | 17 | 0 |
| Headache | 20 | 0 |
| Neurological changes Neurological changes includes amnesia, aphasia, balance disorder,… | 13 | 0 |
| Peripheral neuropathy and paresthesia Peripheral neuropathy and paresthesia includes… | 13 | 1.6 |
| Dizziness | 11 | 0 |
| Insomnia | 13 | 0 |
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: Cytokine Release Syndrome [see Warnings and Precautions (5.1) ]. Immune Effector Cell-Associated Neurotoxicity Syndrome [see Warnings and Precautions (5.2) ]. Infections [see Warnings and Precautions (5.3) ]. Cytopenias [see Warnings and Precautions (5.4) ]. EPKINLY as monotherapy for LBCL or FL: The most common (≥ 20%) adverse reactions are CRS, injection site reactions, fatigue, musculoskeletal pain, fever, diarrhea, COVID-19, rash and abdominal pain. The most common Grade 3 to 4 laboratory abnormalities (≥ 10%) are decreases in lymphocyte count, neutrophil count, hemoglobin, and platelets. ( 6.1 ) EPKINLY in combination with lenalidomide and rituximab for FL: The most common (≥ 20%) adverse reactions are rash, upper respiratory tract infections, fatigue, injection site reactions, constipation, diarrhea, CRS, pneumonia, COVID-19, and fever. The most common Grade 3 to 4 laboratory abnormalities (≥ 10%) are decreased neutrophil count, lymphocyte count, and platelets. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Genmab US, Inc. at 1-855-4GENMAB (1-855-443-6622) or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. …
Source: FDA drug label, Genmab US, Inc., effective June 22, 2026 (SPL set d7836711-b677-412d-bf2d-0f7c8444103a), via openFDA; the full label on DailyMed
What do FAERS reports show?
1,272 reports list epcoritamab among the medicines taken, each a report of something that happened, not proof the medicine caused it; 422 are coded as a death and 295 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, 12 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?
- Epcoritamab: 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