What the label lists and what reports show
Gefitinib side effects
Gefitinib's FDA label: “The most commonly reported adverse drug reactions (ADRs), reported in more than 20% of the patients and greater than placebo were skin reactions and diarrhea.” FAERS holds 8,974 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 malignant neoplasm progression (1,820 reports).
- Generic listed
Check it at the source: the gefitinib FDA label on DailyMed (effective February 28, 2023, AstraZeneca Pharmaceuticals LP); 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 IRESSA?IRESSA may cause serious side effects, including: • lung or breathing problems. IRESSA may cause inflammation of the lung that may lead to death. Symptoms may be similar to those symptoms from lung cancer. Tell your healthcare provider right away if you have any new or worsening lung problems, or any combination of the following symptoms: trouble breathing or shortness of breath, cough, or fever. • liver problems. IRESSA may cause inflammation of the liver that may lead to death. […]
Source: FDA drug label, AstraZeneca Pharmaceuticals LP, effective February 28, 2023 (SPL set 827d60e8-7e07-41b7-c28b-49ef1c4a5a41), via openFDA; the full label on DailyMed
What does the label list?
From the label: adverse reactionsThe most commonly reported adverse drug reactions (ADRs), reported in more than 20% of the patients and greater than placebo were skin reactions and diarrhea.
Table 1 - Selected Adverse Drug Reactions Occurring with an Incidence Rate ≥5% and an Increase of >2% of IRESSA-treated Patients in Study 3
| Reaction | All Grades | Grade 3 and 4 | All Grades | Grade 3 and 4 |
|---|---|---|---|---|
| Skin reactions Includes Acne, Acne pustular, Dermatitis, Dermatitis acneiform, Dermatitis… | 47% | 2% | 17% | 0.4% |
| Nail disorders Includes Ingrowing nail, Nail bed infection, Nail disorder, Nail… | 5% | 0.1% | 0.7% | 0% |
| Diarrhea Includes Diarrhea, Feces soft, Frequent bowel movements | 29% | 3% | 10% | 1% |
| Vomiting | 14% | 1.2% | 10% | 0.4% |
| Stomatitis Includes Aphthous stomatitis, Cheilitis, Glossodynia, Mouth ulceration,… | 7% | 0.3% | 4% | 0.2% |
| Decreased appetite | 17% | 2.3% | 14% | 2.0% |
| Conjunctivitis/blepharitis/dry eye Includes Blepharitis, Conjunctival hyperemia,… | 6% | 0% | 3.2% | 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 drug reactions are discussed in more detail in other sections of the labeling: • Interstitial Lung Disease [see Warnings and Precautions (5.1) ] • Hepatotoxicity [see Warnings and Precautions (5.2) ] • Gastrointestinal Perforation [see Warnings and Precautions (5.3) ] • Severe or Persistent Diarrhea [see Warnings and Precautions (5.4) ] • Ocular Disorders including Keratitis [see Warnings and Precautions (5.5) ] • Bullous and Exfoliative Skin Disorders [see Warning and Precautions (5.6) ] The most commonly reported adverse drug reactions (ADRs), reported in more than 20% of the patients and greater than placebo were skin reactions and diarrhea. (6.1) To report SUSPECTED ADVERSE REACTIONS, contact AstraZeneca at 1-800-236-9933 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. The safety of IRESSA is based on the data from 2462 patients with NSCLC who received IRESSA 250 mg daily monotherapy in three randomized clinical studies (Study 2, Study 3 and Study 4). …
Source: FDA drug label, AstraZeneca Pharmaceuticals LP, effective February 28, 2023 (SPL set 827d60e8-7e07-41b7-c28b-49ef1c4a5a41), via openFDA; the full label on DailyMed
What do FAERS reports show?
8,974 reports list gefitinib among the medicines taken, each a report of something that happened, not proof the medicine caused it; 1,952 are coded as a death and 2,577 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?
- Gefitinib: 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