What the label lists and what reports show
Elranatamab side effects
Elranatamab's FDA label: “Most common adverse reactions (incidence ≥20%) are CRS, fatigue, injection site reaction, diarrhea, upper respiratory tract infection, musculoskeletal pain, pneumonia, decreased appetite, rash, cough, nausea, and pyrexia.” FAERS holds 1,037 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 (184 reports).
- No generic listed
- Boxed warning
Check it at the source: the elranatamab FDA label on DailyMed (effective May 14, 2026, U.S. Pharmaceuticals); 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 ELREXFIO?ELREXFIO may cause serious side effects, including: • See “ What is the most important information I should know about ELREXFIO? ” • Infections. Upper respiratory tract infections and pneumonia are common during treatment with ELREXFIO. ELREXFIO can cause bacterial and viral infections that are severe, life-threatening, or that may lead to death. o Your healthcare provider may prescribe medicines for you to help prevent infections and treat you as needed if you develop an infection during treatment with ELREXFIO. o Tell your healthcare provider right away if you develop any signs or symptoms of an infection during treatment with ELREXFIO, including: ▪ fever of 100.4 °F (38 °C) or higher ▪ chills ▪ cough ▪ shortness of breath ▪ chest pain ▪ sore throat ▪ pain during urination ▪ feeling weak or generally unwell • Decreased white blood cell counts. […]
Source: FDA drug label, BLA761345 (Pfizer Inc), as published by U.S. Pharmaceuticals, effective May 14, 2026 (SPL set aa044060-5b4b-4692-bf0f-9a50e140b10e), via openFDA; the full label on DailyMed
What does the label list?
From the label: adverse reactionsMost common adverse reactions (incidence ≥20%) are CRS, fatigue, injection site reaction, diarrhea, upper respiratory tract infection, musculoskeletal pain, pneumonia, decreased appetite, rash, cough, nausea, and pyrexia.
Table 8. Adverse Reactions (≥10%) in Patients with Relapsed or Refractory Multiple Myeloma Who Received ELREXFIO in MagnetisMM-3
| Reaction | System Organ Class Preferred Term All Grades (%) | ELREXFIO N = 183 Grade 3 or 4 (%) |
|---|---|---|
| Cytokine release syndrome | 58 | 0.5 Only grade 3 adverse reactions occurred. |
| Hypogammaglobulinemia Includes other related terms. | 13 | 2.2 |
| Fatigue | 43 | 6 |
| Injection site reaction | 37 | 0 |
| Pyrexia | 21 | 2.7 |
| Edema | 18 | 1.1 |
| Diarrhea | 36 | 1.1 |
| Nausea | 21 | 0 |
| Constipation | 14 | 0 |
| Vomiting | 14 | 0 |
| Upper respiratory tract infection | 36 | 4.9 |
| Pneumonia Pneumonia includes COVID-19 pneumonia, lower respiratory tract infection, lower… | 32 | 19 |
| Sepsis Sepsis includes bacteremia, device related bacteremia, device related sepsis,… | 15 | 11 |
| Urinary tract infection | 12 | 4.4 |
| Musculoskeletal pain | 34 | 2.7 |
| Decreased appetite | 26 | 1.1 |
| Rash Rash incudes erythema, palmar-plantar erythrodysesthesia syndrome, rash, rash… | 26 | 0 |
| Dry skin | 14 | 0 |
| Skin exfoliation | 10 | 0 |
| Cough | 24 | 0 |
| Dyspnea | 15 | 3.3 |
| Headache | 18 | 0 |
| Encephalopathy Encephalopathy includes agitation, altered state of consciousness,… | 14 | 2.2 |
| Sensory neuropathy Sensory neuropathy includes burning sensation, dysesthesia,… | 13 | 0.5 |
| Motor dysfunction Motor dysfunction includes ataxia, balance disorder, gait disturbance,… | 14 | 1.1 |
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 adverse reactions are discussed elsewhere in labeling: • Cytokine Release Syndrome [see Warnings and Precautions (5.1) ]. • Neurologic Toxicity, Including ICANS [see Warnings and Precautions (5.2) ]. • Infections [see Warnings and Precautions (5.4) ]. • Neutropenia [see Warnings and Precautions (5.5) ]. • Hepatotoxicity [see Warnings and Precautions (5.6) ]. Most common adverse reactions (incidence ≥20%) are CRS, fatigue, injection site reaction, diarrhea, upper respiratory tract infection, musculoskeletal pain, pneumonia, decreased appetite, rash, cough, nausea, and pyrexia. The most common Grade 3 to 4 laboratory abnormalities (≥30%) are decreased lymphocytes, decreased neutrophils, decreased hemoglobin, decreased white blood cells, and decreased platelets. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Pfizer Inc. at 1-800-438-1985 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. Relapsed/Refractory Multiple Myeloma MagnetisMM-3 The safety of ELREXFIO was evaluated in MagnetisMM-3 [see Clinical Studies (14) ]. …
Source: FDA drug label, BLA761345 (Pfizer Inc), as published by U.S. Pharmaceuticals, effective May 14, 2026 (SPL set aa044060-5b4b-4692-bf0f-9a50e140b10e), via openFDA; the full label on DailyMed
What do FAERS reports show?
1,037 reports list elranatamab among the medicines taken, each a report of something that happened, not proof the medicine caused it; 244 are coded as a death and 299 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 23 reactions below, 16 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?
- Elranatamab: 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