What the label lists and what reports show
Cetuximab side effects
Cetuximab's FDA label: “The most common adverse reactions (incidence ≥25%) with Erbitux as a single-agent or in combination with radiotherapy or chemotherapy (FOLFIRI, Irinotecan and 5-Fluorouracil/Platinum) are: cutaneous adverse reactions (including rash, pruritus, and nail …” FAERS holds 31,149 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 rash (2,273 reports).
- No generic listed
- Boxed warning
Check it at the source: the cetuximab FDA label on DailyMed (effective April 16, 2026, ImClone LLC); the FDA FAERS public dashboard.
What does the label list?
From the label: adverse reactionsThe most common adverse reactions (incidence ≥25%) with Erbitux as a single-agent or in combination with radiotherapy or chemotherapy (FOLFIRI, Irinotecan and 5-Fluorouracil/Platinum) are: cutaneous adverse reactions (including rash, pruritus, and nail changes), headache, diarrhea, and infection.
Table 5: Selected Adverse Reactions in ≥10% of Patients with K-Ras Wild-type, EGFR-expressing, Metastatic Colorectal Cancer Treated with Single-Agent ERBITUX (Study CA225-025) a
| Reaction | Grades 1–4 b | Grades 3 and 4 | Grades 1–4 | Grades 3 and 4 |
|---|---|---|---|---|
| Rash/Desquamation | 95 | 16 | 21 | 1 |
| Dry Skin | 57 | 0 | 15 | 0 |
| Pruritus | 47 | 2 | 11 | 0 |
| Other-Dermatology | 35 | 0 | 7 | 2 |
| Nail Changes | 31 | 0 | 4 | 0 |
| Fatigue | 91 | 31 | 79 | 29 |
| Fever | 25 | 3 | 16 | 0 |
| Infusion Reactions c | 18 | 3 | 0 | 0 |
| Rigors, Chills | 16 | 1 | 3 | 0 |
| Pain-Other | 59 | 18 | 37 | 10 |
| Headache | 38 | 2 | 11 | 0 |
| Bone Pain | 15 | 4 | 8 | 2 |
| Dyspnea | 49 | 16 | 44 | 13 |
| Cough | 30 | 2 | 19 | 2 |
| Nausea | 64 | 6 | 50 | 6 |
| Constipation | 53 | 3 | 38 | 3 |
| Diarrhea | 42 | 2 | 23 | 2 |
| Vomiting | 40 | 5 | 26 | 5 |
| Stomatitis | 32 | 1 | 10 | 0 |
| Other | 22 | 12 | 16 | 5 |
| Dehydration | 13 | 5 | 3 | 0 |
| Mouth Dryness | 12 | 0 | 6 | 0 |
| Taste Disturbance | 10 | 0 | 5 | 0 |
| Infection without neutropenia | 38 | 11 | 19 | 5 |
| Arthralgia | 14 | 3 | 6 | 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 discussed in greater detail in other sections of the label: Infusion reactions [see Warnings and Precautions ( 5.1 )]. Cardiopulmonary arrest [see Warnings and Precautions ( 5.2 )]. Pulmonary toxicity [see Warnings and Precautions ( 5.3 )]. Dermatologic toxicity [see Warnings and Precautions ( 5.4 )]. Hypomagnesemia and Electrolyte Abnormalities [see Warnings and Precautions ( 5.6 )]. The most common adverse reactions (incidence ≥25%) with Erbitux as a single-agent or in combination with radiotherapy or chemotherapy (FOLFIRI, Irinotecan and 5-Fluorouracil/Platinum) are: cutaneous adverse reactions (including rash, pruritus, and nail changes), headache, diarrhea, and infection. ( 6 ) The most common adverse reactions (>25%) for ERBITUX, in combination with encorafenib, are fatigue, nausea, diarrhea, dermatitis acneiform, abdominal pain, decreased appetite, arthralgia, and rash. ( 6 ). To report SUSPECTED ADVERSE REACTIONS, contact Eli Lilly and Company at 1-800-LillyRx (1-800-545-5979) 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.
Source: FDA drug label, ImClone LLC, effective April 16, 2026 (SPL set 8bc6397e-4bd8-4d37-a007-a327e4da34d9), via openFDA; the full label on DailyMed
What do FAERS reports show?
31,149 reports list cetuximab among the medicines taken, each a report of something that happened, not proof the medicine caused it; 4,217 are coded as a death and 12,520 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, 19 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?
- Cetuximab: 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