What the label lists and what reports show
Teclistamab side effects
Teclistamab's FDA label: “The most common adverse reactions (≥20%) in patients who received TECVAYLI monotherapy are pyrexia, cytokine release syndrome, musculoskeletal pain, injection site reaction, fatigue, upper respiratory tract infection, nausea, headache, pneumonia, and diarrhea.” FAERS holds 2,119 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 (508 reports).
- No generic listed
- Boxed warning
Check it at the source: the teclistamab FDA label on DailyMed (effective March 10, 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 TECVAYLI?TECVAYLI can cause serious side effects, including: See " What is the most important information I should know about TECVAYLI? " Liver problems. TECVAYLI can cause liver problems that may cause death. Increases in liver enzymes can happen with or without CRS. Tell your healthcare provider right away if you develop any symptoms of a liver problem including: tiredness loss of appetite pain in your right upper stomach-area (abdomen) dark urine yellowing of your skin or white part of your eyes Infections. TECVAYLI can cause bacterial and viral infections that are severe, life-threatening, or that may cause death. Your healthcare provider may prescribe medicines to help prevent infections and treat you as needed if you develop an infection during treatment with TECVAYLI. Tell your healthcare provider right away if you get a fever, chills or any signs or symptoms of an infection. […]
Source: FDA drug label, Janssen Biotech, Inc., effective March 10, 2026 (SPL set 54e0f974-ccee-44ea-9254-40e9883cee1e), via openFDA; the full label on DailyMed
What does the label list?
From the label: adverse reactionsThe most common adverse reactions (≥20%) in patients who received TECVAYLI monotherapy are pyrexia, cytokine release syndrome, musculoskeletal pain, injection site reaction, fatigue, upper respiratory tract infection, nausea, headache, pneumonia, and diarrhea.
Table 12: Adverse Reactions (≥10%) in Patients with Multiple Myeloma Who Received TECVAYLI in Combination with Daratumumab and Hyaluronidase-fihj in MajesTEC-3
| Reaction | Any Grade (%) | Grade 3 or 4 (%) | Any Grade (%) | Grade 3 or 4 (%) |
|---|---|---|---|---|
| Hypogammaglobulinemia Hypogammaglobulinemia includes hypogammaglobulinemia,… | 84 | 6 | 60 | 1.4 |
| Cytokine release syndrome | 60 | 0 | 0 | 0 |
| Upper respiratory tract infection Upper respiratory tract infection includes bronchitis,… | 79 | 17 | 62 | 13 |
| COVID-19 Includes other related terms. | 45 | 6 | 33 | 2.1 |
| Pneumonia Pneumonia includes atypical pneumonia, bacterial pneumonia, fungal pneumonia,… | 42 | 33 | 35 | 28 |
| Gastroenteritis | 20 | 4.9 | 8 | 0.7 |
| Urinary tract infection | 17 | 2.8 | 13 | 1 |
| Herpes virus infection | 11 | 2.1 | 6 | 0.3 |
| Cough | 53 | 0.7 | 24 | 0 |
| Dyspnea | 13 | 1.8 | 20 | 2.1 |
| Diarrhea | 52 | 3.9 | 31 | 2.4 |
| Nausea | 23 | 0 | 12 | 0.3 |
| Vomiting | 17 | 0 | 7 | 0 |
| Abdominal pain | 16 | 0.7 | 13 | 0 |
| Constipation | 14 | 0 | 20 | 0.3 |
| Musculoskeletal pain | 50 | 1.4 | 47 | 4.5 |
| Injection site reaction Includes injection site reactions related to teclistamab,… | 41 | 0 | 4.5 | 0 |
| Fatigue | 39 | 3.9 | 40 | 4.1 |
| Pyrexia | 37 | 1.4 | 19 | 0.3 |
| Edema | 13 | 0.4 | 22 | 0.3 |
| Headache | 26 | 1.4 | 12 | 0.3 |
| Sensory neuropathy Sensory neuropathy includes dysaesthesia, hyperaesthesia,… | 17 | 0.7 | 25 | 0.3 |
| Motor dysfunction Motor dysfunction includes balance disorder, dysarthria, dysphonia,… | 14 | 0 | 30 | 1 |
| Weight decreased | 20 | 2.8 | 7 | 1.4 |
| Decreased appetite | 19 | 1.1 | 7 | 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 adverse reactions are also described elsewhere in the labeling: Cytokine Release Syndrome [see Warnings and Precautions (5.1) ] Neurologic Toxicity including ICANS [see Warnings and Precautions (5.2) ] Hepatotoxicity [see Warnings and Precautions (5.4) ] Infections [see Warnings and Precautions (5.5) ] Neutropenia [see Warnings and Precautions (5.6) ] Hypersensitivity and Other Administration Reactions [see Warnings and Precautions (5.7) ] The most common adverse reactions (≥20%) in patients who received TECVAYLI monotherapy are pyrexia, cytokine release syndrome, musculoskeletal pain, injection site reaction, fatigue, upper respiratory tract infection, nausea, headache, pneumonia, and diarrhea. ( 6.1 ) The most common adverse reactions (≥20%) in patients who received TECVAYLI in combination with daratumumab and hyaluronidase-fihj are hypogammaglobulinemia, upper respiratory tract infection, cytokine release syndrome, cough, diarrhea, musculoskeletal pain, COVID-19, pneumonia, injection site reaction, fatigue, pyrexia, headache, nausea, gastroenteritis and weight decreased. ( 6.1 ) The most common Grade 3 to 4 laboratory abnormalities (≥20%) with TECVAYLI (as monotherapy or in combination with daratumumab and hyaluronidase-fihj) are decreased lymphocytes, decreased neutrophils, decreased white blood cells, decreased hemoglobin, and decreased platelets.
Source: FDA drug label, Janssen Biotech, Inc., effective March 10, 2026 (SPL set 54e0f974-ccee-44ea-9254-40e9883cee1e), via openFDA; the full label on DailyMed
What do FAERS reports show?
2,119 reports list teclistamab among the medicines taken, each a report of something that happened, not proof the medicine caused it; 421 are coded as a death and 519 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, 17 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?
- Teclistamab: 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