Gefitinib
Gefitinib is a targeted cancer medicine (a tyrosine kinase inhibitor) used as first-line treatment for metastatic non-small cell lung cancer whose tumors have certain EGFR mutations.
🧬 Where this information comes from Click to expand
The clinical label records used on this page are FDA-filed Structured Product Labeling (SPL) retrieved through openFDA. We identified 5 clinical label sets within the page’s selected clinical scope after exact ingredient or ingredient-combination matching and applicable route/form matching. Forms, routes, brands, labelers, strengths, and NDC product-record counts are built separately from matching FDA National Drug Code Directory records. The linked DailyMed document is a representative official source for verification, not the page’s only clinical source. View the linked label on DailyMed →
Gefitinib (Iressa) is a once-daily targeted tablet for metastatic non-small cell lung cancer with specific EGFR mutations, blocking EGFR, the growth signal those tumors rely on. One of the first drugs of its kind, it has been on the U.S. market since about 2014 and is available as a generic. Most people find it easier going than chemotherapy, though an acne-like rash, dry skin and diarrhea are common. The rare danger is interstitial lung disease (lung inflammation, occasionally fatal), so report new or worsening shortness of breath, cough or fever right away.
Clinical pearls
- Expect periodic liver blood tests, and report severe diarrhea, eye pain or blistering skin promptly.
- Acid reducers lower gefitinib levels, so avoid proton pump inhibitors (or separate by 12 hours) and keep antacids or H2-blockers 6 hours apart.
- If you take warfarin, expect regular INR checks, since INR rises and bleeding have been reported with gefitinib.
- Use effective contraception throughout treatment and for at least two weeks after the last dose, and do not breastfeed.
Patient information guide A plain-language walkthrough of Gefitinib, written from its FDA label.
What Gefitinib is used for
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Gefitinib is used for one cancer indication.
- Iressa (oral tablet): first-line treatment of metastatic non-small cell lung cancer with EGFR exon 19 deletions or exon 21 (L858R) mutations, found by an FDA-approved test.
- Gefitinib tablets (oral): the same first-line use.
- Not established for tumors with other EGFR mutations.
How Gefitinib works
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Gefitinib is a tyrosine kinase inhibitor. It reversibly blocks the EGFR protein on cell surfaces, which in some lung cancers is mutated and drives tumor growth and spread.
It binds more tightly to the common mutated forms (exon 19 deletion and L858R) than to normal EGFR. It also blocks IGF and PDGF signaling.
Gefitinib dosage
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Gefitinib is taken by mouth once daily, with or without food, until the cancer progresses or side effects become unacceptable.
- Do not take a missed dose within 12 hours of the next dose.
- If you can't swallow tablets, the label describes stirring one in water for about 15 minutes and drinking it right away.
- Your doctor may pause the medicine for side effects, or change the dose if you take certain interacting drugs.
Dosing details from the FDA-approved label
From the Gefitinib prescribing information (“Dosage and Administration”). Doses are set by your prescriber for your product, condition, kidney function and age — never change a dose on your own.
- First-line treatment of metastatic NSCLC with EGFR exon 19 deletions or exon 21 L858R mutations
- 250 mg orally once daily with or without food until disease progression or unacceptable toxicity
- Do not take a missed dose within 12 hours of the next dose
- For patients who have difficulty swallowing solids, immerse tablet in 4 to 8 ounces of water, stir for approximately 15 minutes, and drink immediately or give through a naso-gastric tube
- Adverse drug reactions (pulmonary symptoms, ALT/AST elevations Grade 2 or higher, diarrhea Grade 3 or higher, severe or worsening ocular disorders, skin reactions Grade 3 or higher)
- Withhold for up to 14 days
- Resume treatment when the adverse reaction fully resolves or improves to NCI CTCAE Grade 1
- Permanently discontinue for confirmed interstitial lung disease, severe hepatic impairment, gastrointestinal perforation, or persistent ulcerative keratitis
- Patients receiving strong CYP3A4 inducers
- Increase to 500 mg daily in the absence of severe adverse drug reaction
- Resume 250 mg seven days after discontinuation of the strong CYP3A4 inducer
Read the label’s full dosing text
2 DOSAGE AND ADMINISTRATION Recommended dose is 250 mg orally, once daily with or without food. (2.2) 2.1 Patient Selection Select patients for the first-line treatment of metastatic NSCLC with gefitinib tablets based on the presence of EGFR exon 19 deletions or exon 21 L858R mutations in their tumor or plasma specimens[ see Indications and Usage (1) , Clinical Studies (14) ]. If these mutations are not detected in a plasma specimen, test tumor tissue if feasible. Information on FDA-approved tests for the detection of EGFR mutations in NSCLC is available at: http://www.fda.gov/CompanionDiagnostics . 2.2 Recommended Dose The recommended dose of gefitinib tablets is 250 mg orally once daily with or without food until disease progression or unacceptable toxicity. Do not take a missed dose within 12 hours of the next dose. 2.3 Administration to Patients Who Have Difficulty Swallowing Solids Immerse gefitinib tablets in 4 to 8 ounces of water by dropping the tablet in water, and stir for approximately 15 minutes. Immediately drink the liquid or administer through a naso-gastric tube. Rinse the container with 4 to 8 ounces of water and immediately drink or administer through the naso-gastric tube. 2.4 Dose Modification Dose Modifications for Adverse Drug Reactions Withhold gefitinib tablets (for up to 14 days) for any of the following: •Acute onset or worsening of pulmonary symptoms (dyspnea, cough, fever) [ see Warnings and Precautions (5.1) ] •NCI CTCAE Grade 2 or higher in ALT and/or AST elevations [ see Warnings and Precautions (5.2) ] •NCI CTCAE Grade 3 or higher diarrhea [ see Warnings and Precautions (5.4) ] •Signs and symptoms of severe or worsening ocular disorders including keratitis [ see Warnings and Precautions (5.5) ] •NCI CTCAE Grade 3 or higher skin reactions [ see Warnings and Precautions (5.6) ] Resume treatment with gefitinib tablets when the adverse reaction fully resolves or improves to NCI CTCAE Grade 1.
Excerpted — the section continues on the label. Read the full Dosage and Administration section on DailyMed →
Gefitinib side effects
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The most common side effects are skin reactions and diarrhea.
Common side effects
- Skin reactions such as rash, acne-like skin problems and dry skin
- Diarrhea
- Decreased appetite
- Nausea and vomiting
- Weakness (asthenia)
- Mouth sores (stomatitis)
- Eye irritation, conjunctivitis or dry eye
- Raised liver enzymes on blood tests
When to get medical help
- Call your doctor right away if you have new or worsening shortness of breath, cough or fever (possible interstitial lung disease).
- Report severe or persistent diarrhea.
- Report yellowing of skin or eyes, or other signs of liver problems; you will need periodic liver tests.
- Get help for severe stomach pain, which could signal a gastrointestinal perforation (a hole in the gut wall).
- Report eye pain, redness or worsening eye symptoms.
- Report severe blistering, peeling or widespread skin reactions.
- Tell your doctor about unusual bleeding, especially if you take warfarin.
Gefitinib warnings and precautions
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- Interstitial lung disease: occurred in about 1.3% of patients in trials, and a few cases were fatal. Watch for worsening cough, fever or shortness of breath.
- Liver toxicity: raised liver enzymes are common; periodic liver tests are needed.
- Gastrointestinal perforation: rare; treatment is permanently stopped.
- Severe diarrhea, eye disorders and blistering skin conditions: treatment may be paused or stopped.
- Fetal harm: use effective contraception.
Gefitinib interactions
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Several drugs change gefitinib levels or its effects.
- Strong CYP3A4 inducers (rifampicin, phenytoin, tricyclic antidepressants): lower gefitinib levels, so the dose may be raised.
- Strong CYP3A4 inhibitors (ketoconazole, itraconazole): raise levels, so monitoring is needed.
- Proton pump inhibitors: may reduce levels; avoid if possible.
- H2-blockers and antacids: may reduce levels; separate by 6 hours.
- Warfarin: higher INR and bleeding reported; monitor regularly.
- CYP2D6 inhibitors: possible higher gefitinib exposure.
Interactions listed in the FDA-approved label
From the Gefitinib prescribing information (“Drug Interactions”): what the manufacturer studied or reported to the FDA.
- Strong CYP3A4 inducers (e.g., rifampicin, phenytoin, or tricyclic antidepressant): Increase the metabolism of gefitinib and decrease gefitinib plasma concentrations. Increase gefitinib to 500 mg daily and resume 250 mg 7 days after discontinuation of the strong inducer.
- Strong CYP3A4 inhibitors (e.g., ketoconazole and itraconazole): Decrease gefitinib metabolism and increase gefitinib plasma concentrations. Monitor adverse reactions.
- Proton pump inhibitors: Drugs that elevate gastric pH may reduce plasma concentrations of gefitinib. Avoid concomitant use if possible. If required, take gefitinib 12 hours after the last dose or 12 hours before the next dose of the proton-pump inhibitor.
- Histamine H2-receptor antagonists and antacids: Drugs that elevate gastric pH may reduce plasma concentrations of gefitinib. Take gefitinib 6 hours after or 6 hours before an H2-receptor antagonist or an antacid.
- Warfarin: INR elevations and/or hemorrhage have been reported in some patients taking warfarin while on gefitinib therapy. Monitor regularly for changes in prothrombin time or INR.
Read the label’s full interactions text
7 DRUG INTERACTIONS •CYP3A4 Inducer: Increase gefitinib tablets to 500 mg daily in patients receiving a strong CYP3A4 inducer. ( 2.4 , 7.1 ) •CYP3A4 Inhibitor: Monitor adverse reactions if concomitant use with gefitinib tablets. ( 7.1 ) •Drugs Affecting Gastric pH: Avoid concomitant use of gefitinib tablets with proton pump inhibitors, if possible. ( 7.1 ) •Hemorrhage in patients taking warfarin: Monitor changes in prothrombin time or INR. ( 7.2 ) 7.1 Drugs Affecting Gefitinib Exposure CYP3A4 Inducer Drugs that are strong inducers of CYP3A4 increase the metabolism of gefitinib and decrease gefitinib plasma concentrations. Increase gefitinib tablets to 500 mg daily in patients receiving a strong CYP3A4 inducer (e.g., rifampicin, phenytoin, or tricyclic antidepressant) and resume gefitinib tablets at 250 mg 7 days after discontinuation of the strong inducer [ see Dosage and Administration (2.4) , Clinical Pharmacology (12.3) ]. CYP3A4 Inhibitor Drugs that are strong inhibitors of CYP3A4 (e.g., ketoconazole and itraconazole) decrease gefitinib metabolism and increase gefitinib plasma concentrations. Monitor adverse reactions when administering strong CYP3A4 inhibitors with gefitinib tablets. Drugs Affecting Gastric pH Drugs that elevate gastric pH (e.g., proton pump inhibitors, histamine H 2 -receptor antagonists, and antacids) may reduce plasma concentrations of gefitinib. Avoid concomitant use of gefitinib tablets with proton pump inhibitors, if possible. If treatment with a proton-pump inhibitor is required, take gefitinib tablets 12 hours after the last dose or 12 hours before the next dose of the proton-pump inhibitor. Take gefitinib tablets 6 hours after or 6 hours before an H 2 -receptor antagonist or an antacid [ see Clinical Pharmacology (12.3) ]. 7.2 Hemorrhage in Patients taking Warfarin International Normalized Ratio (INR) elevations and/or hemorrhage have been reported in some patients taking warfarin while on gefitinib tablets therapy.
Excerpted — the section continues on the label. Read the full Drug Interactions section on DailyMed →
Not a complete list. The label covers the interactions the manufacturer studied or reported, and our own interaction database does not cover every medicine either. Bring your full medication list, including vitamins and herbal products, to your pharmacist.
Before taking Gefitinib
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- No contraindications are listed.
- Tell your doctor about liver disease; exposure is higher with liver impairment.
- Pregnancy: can cause fetal harm; use contraception during treatment and for at least two weeks after.
- Breastfeeding: stop during treatment.
- May reduce fertility in females who can become pregnant.
- Children: safety and effectiveness not established.
- Older adults: no overall safety differences seen.
- CYP2D6 poor metabolizers: closer monitoring advised.
Gefitinib overdose
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In studies, people given much higher weekly doses mostly had mild to moderate side effects like those already known. If an overdose is suspected, the medicine is interrupted, supportive care is given and the person is observed until stable. There is no specific antidote.
How your body processes Gefitinib
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About 60% of an oral dose is absorbed, with peak levels 3 to 7 hours after dosing. Food does not meaningfully change this. Gefitinib is broken down mainly in the liver, mostly by CYP3A4, and leaves mostly in the stool. Its half-life is about 48 hours and steady levels build up within about 10 days of daily use.
How to store Gefitinib
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Store at controlled room temperature 20°C-25°C (68°F-77°F) .
Written from the FDA-approved label with AI and reviewed by our pharmacy team. How we use AI →
Supplements & herbs that interact with Gefitinib
168 supplements and herbal products have documented interactions with Gefitinib in the licensed clinical database we use. Most are manageable — but your pharmacist should know about everything you take, including vitamins and herbals.
- Major · 6
- Moderate · 124
- Minor · 38
Educational information from a licensed clinical database (Natural Medicines) — see our data sources & update cadence. Not medical advice: an interaction being documented does not mean it will happen to you; do not start or stop medications or supplements without professional guidance.
Gefitinib: pharmacist answers to common questions
Quick, plain-English answers to the questions patients ask most about Gefitinib — the kind of thing our pharmacy team would talk through with you at the counter.
What is gefitinib for?
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How do I take it?
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What side effects should I expect?
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When should I call my doctor right away?
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Can I take it with my heartburn medicine?
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Is it safe in pregnancy?
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Is Gefitinib available over the counter?
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When was Gefitinib first available?
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Who makes Gefitinib?
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Answers drafted from the FDA-approved label with AI and reviewed by our pharmacy team. How we use AI →
More about Gefitinib on HelloPharmacist
Gefitinib forms and strengths (how it comes)
Gefitinib is available in 1 form. Different forms and brands can have different approved uses, doses, schedules, and directions. Follow the instructions for your exact product, and do not switch forms without guidance from your prescriber or pharmacist.
Need a version that does not list lactose, a gluten source, a dye or gelatin? Inactive ingredients differ by manufacturer: see Gefitinib inactive ingredients by manufacturer.
Tablet
How this form is used
- Iressa is used for first-line treatment of metastatic NSCLC with EGFR exon 19 deletions or exon 21 (L858R) mutations.
- Gefitinib tablets are used for first-line treatment of metastatic NSCLC with EGFR exon 19 deletions or exon 21 (L858R) mutations.
- Iressa is taken by mouth once daily, with or without food.
- Gefitinib tablets are taken by mouth once daily, with or without food.
- Iressa tablets can be dropped in water and stirred for about 15 minutes if swallowing is difficult; drink right away.
- Gefitinib tablets can be dispersed in water the same way, then rinse the container and drink that too.
Gefitinib on the U.S. market: products, makers and brands
How Gefitinib appears in the FDA’s National Drug Code Directory — including its dosage forms, strengths, brand names, manufacturers, and FDA-listed product records. These are directory records, not sales or prescription volume.
5 companies list 5 Gefitinib product records with the FDA, mostly as tablet; the earliest marketing or approval year on record is 2003. Brand names on the directory include Iressa; the rest are generics.
Also listed with the FDA, not a patient dose form: Powder (7) — bulk drug substance sold to compounders/manufacturers and multi-item kits. These aren’t counted in the dose-form total above.
Share of FDA-listed product records by manufacturer — FDA National Drug Code Directory. Record counts are not sales or prescription volume.
Compare Gefitinib products
A representative set of FDA-listed product records for Gefitinib — across manufacturers, strengths, and dosage forms, grouped by form with each product’s manufacturer and how the FDA approved it. The same medicine may be made and packaged by different companies, so a single drug can have many directory entries. (It’s also why a refill can look different — a new shape, color, or box — even though it contains the same medication.)
| Strength | Route | Manufacturer / Labeler | Category ⓘ | Details |
|---|---|---|---|---|
| 💊Tablet | ||||
| 250 mg | Oral | AstraZeneca Pharmaceuticals LP | NDA | View NDC → |
| 250 mg | Oral | Ingenus Pharmaceuticals, LLC | ANDA | View NDC → |
| 250 mg | Oral | Natco Pharma USA LLC | ANDA | View NDC → |
| 250 mg | Oral | Qilu Pharmaceutical Co., Ltd. | ANDA | View NDC → |
| 250 mg | Oral | Teva Pharmaceuticals, Inc. | ANDA | View NDC → |
Showing 5 of 5 products — FDA National Drug Code Directory. See every product, package size and price: browse all 5 Gefitinib NDCs →
Gefitinib side effects reported to the FDA (FAERS)
After a medicine reaches the market, patients, doctors and drugmakers can send the FDA reports of problems they think may be linked to it. Here’s what’s been reported for Gefitinib — a signal of what to watch for, not proof the drug caused it.
Source: openFDA, from the FDA Adverse Event Reporting System (FAERS). These are voluntary reports — they don’t prove the drug caused the effect, and counts reflect how often something was reported, not how often it actually happens. Reports also often name the very problem the medicine is taken for — a common reason to file one is that the drug didn’t help — so for a pain reliever you may see “pain” high on the list; that points to why the report was filed, not to the drug causing the symptom. This counts every report that lists Gefitinib in any role, so the total runs higher than the FDA’s official dashboard, which counts only cases where the drug is the suspect. For the authoritative figures, see the FDA FAERS Public Dashboard. Always talk to your pharmacist or doctor.
Gefitinib FDA approval history
How Gefitinib went from FDA review to the pharmacy shelf — the key milestones in its regulatory journey.
Source: Drugs@FDA.
Gefitinib recall history
A recall is when a specific batch of a medicine is pulled from the market — usually a manufacturing issue, not a problem with the drug itself. Class I is most serious, Class III least.
The FDA’s enforcement reports list no Gefitinib recalls since July 2021.
✅No Gefitinib recalls on record since July 2021Source: FDA enforcement (recall) reports, via openFDA; our copy was last updated Sep 24, 2026.
RxNorm Concept Web — From Ingredient to Every Form and Strength
This page starts with one ingredient concept (IN). The branches below show its dose-form concepts (SCDF), then the available clinical drug and strength concepts (SCD). Combination products remain separate concepts with their own pages.
RxCUI 328134 1 dose form · 1 strength
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Dose form (SCDF) Oral Tablet RxCUI 378629In current FDA listingsClinical drug / strength (SCD) 250 MGRxCUI 349472
Look up RxCUI 328134 in the RxCUI Atlas →
RxNorm is the U.S. National Library of Medicine’s normalized drug vocabulary. Its concept hierarchy can include forms that are not currently marketed; the status on each branch compares that concept with current FDA listings. RxCUIs identify vocabulary concepts, not individual packages or manufacturers.
Gefitinib supply and shortage status
Whether Gefitinib is in short supply in the U.S. right now, plus any shortage history the FDA has on record. A shortage usually reflects a manufacturing or demand issue — not a safety problem with the drug.
Source: openFDA, from the FDA Drug Shortages database.
Gefitinib brand names
Gefitinib is sold under one brand name in the FDA directory — Iressa. A brand and its generic contain the same active ingredient; the brand name belongs to one company's product.
Who makes Gefitinib: manufacturers and labelers
5 companies list Gefitinib products with the FDA. By number of product records, the largest are AstraZeneca Pharmaceuticals LP, Ingenus Pharmaceuticals, LLC, Natco Pharma USA LLC. Labelers include manufacturers and repackagers; the product in your bottle depends on which one your pharmacy stocks.
Gefitinib drug class (RxNorm)
Gefitinib belongs to the Kinase Inhibitor class.
Classified by RxNorm RxClass — the U.S. National Library of Medicine's standardized drug-classification service (Established Pharmacologic Class from the FDA, the ATC drug family from the WHO, and mechanism of action). Reference only, not medical advice.
Sources for this Gefitinib page
Core label, product, RxNorm, safety, and utilization data on this page come from the sources identified below. AI-written, editorial, and licensed sections are labeled separately.
How this page is built
HelloPharmacist combines public FDA and NLM records and does not author the underlying clinical facts. The plain-language sections are written with AI from the FDA-approved label text and reviewed by our pharmacy team before publication. AstraZeneca Pharmaceuticals LP is the representative DailyMed label linked for verification and dates. This is general education, not medical advice: always talk to your doctor or pharmacist about your own medicines. How we build and review drug pages →