What the label lists and what reports show
Zolbetuximab side effects
Zolbetuximab's FDA label: “The most common adverse reactions (≥15%) for VYLOY in combination with mFOLFOX6 or CAPOX were nausea, vomiting, fatigue, decreased appetite, diarrhea, peripheral sensory neuropathy, abdominal pain, constipation, decreased weight, hypersensitivity reactions …” FAERS holds 1,293 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 nausea (499 reports).
- No generic listed
Check it at the source: the zolbetuximab FDA label on DailyMed (effective August 11, 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 VYLOY?VYLOY may cause serious side effects, including: • Allergic reactions, including anaphylaxis and infusion related reactions. Allergic reactions are common during treatment with VYLOY and can sometimes be serious. Serious allergic reactions can happen during or after your VYLOY infusion, including life-threatening allergic reactions and serious infusion-related reactions that may lead to death. Your healthcare provider will monitor you during your infusion and for 2 hours after or longer if needed. […]
Source: FDA drug label, Astellas Pharma US, Inc., effective August 11, 2026 (SPL set e7695a21-abb6-47ac-93f8-0ece5a9c4409), via openFDA; the full label on DailyMed
What does the label list?
From the label: adverse reactionsThe most common adverse reactions (≥15%) for VYLOY in combination with mFOLFOX6 or CAPOX were nausea, vomiting, fatigue, decreased appetite, diarrhea, peripheral sensory neuropathy, abdominal pain, constipation, decreased weight, hypersensitivity reactions, and pyrexia.
Table 5. Adverse Reactions (≥15%) in Patients Treated with VYLOY in GLOW with a Difference Between Arms of ≥5% Compared to Placebo
| Reaction | All Grades % | Grade 3 or 4 % | All Grades % | Grade 3 or 4 % |
|---|---|---|---|---|
| Nausea | 69 | 9 | 50 | 2.4 |
| Vomiting | 66 | 12 | 31 | 3.6 |
| Decreased appetite | 41 | 7 | 34 | 1.6 |
| Neutropenia | 20 | 7 | 14 | 2.8 |
| Weight decreased | 20 | 0.4 | 10 | 0.4 |
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 serious adverse reactions are described elsewhere in the labeling: • Hypersensitivity Reactions, including anaphylaxis, and infusion related reactions [see Warnings and Precautions ( 5.1 )]. • Severe Nausea and Vomiting [see Warnings and Precautions ( 5.2 )]. The most common adverse reactions (≥15%) for VYLOY in combination with mFOLFOX6 or CAPOX were nausea, vomiting, fatigue, decreased appetite, diarrhea, peripheral sensory neuropathy, abdominal pain, constipation, decreased weight, hypersensitivity reactions, and pyrexia. The most common laboratory abnormalities (≥15%) for VYLOY in combination with mFOLFOX6 or CAPOX were decreased neutrophil count, decreased leucocyte count, decreased albumin, increased creatinine, decreased hemoglobin, increased glucose, decreased lymphocyte count, increased aspartate aminotransferase, decreased platelets, increased alkaline phosphatase, increased alanine aminotransferase, decreased glucose, decreased sodium, decreased phosphate, decreased potassium, and decreased magnesium ( 6.1 ). To report SUSPECTED ADVERSE REACTIONS, contact Astellas Pharma US, Inc. at 1-800-727-7003 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. …
Source: FDA drug label, Astellas Pharma US, Inc., effective August 11, 2026 (SPL set e7695a21-abb6-47ac-93f8-0ece5a9c4409), via openFDA; the full label on DailyMed
What do FAERS reports show?
1,293 reports list zolbetuximab among the medicines taken, each a report of something that happened, not proof the medicine caused it; 160 are coded as a death and 438 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, 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?
- Zolbetuximab: 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