Reviewed on 6/29/2022

What Is Gefitinib and How Does It Work?

Gefitinib is a prescription medication used to treat the symptoms of malignant non-small cell lung cancer (NSCLC).

  • Gefitinib is available under the following different brand names: Iressa

What Are Dosages of Gefitinib?

Adult dosage


  • 250 mg

Non-small Cell Lung Cancer

  • 250 mg orally once a day until disease progression or unacceptable toxicity

Dosage Considerations – Should be Given as Follows: 

  • See “Dosages”

What Are Side Effects Associated with Using Gefitinib?

Common side effects of Gefitinib include:

  • skin reactions,
  • nail disorders,
  • diarrhea,
  • vomiting,
  • inflammation of the mouth lining,
  • decreased appetite,
  • eyelid swelling, and
  • dry eye.

Serious side effects of Gefitinib include:

  • unusual bleeding (coughing up blood, blood in urine),
  • eye irritation or pain, or
  • swelling of the ankles or feet.

Rare side effects of Gefitinib include:

  • none

Seek medical care or call 911 at once if you have the following serious side effects:

  • Severe headache, confusion, slurred speech, arm or leg weakness, trouble walking, loss of coordination, feeling unsteady, very stiff muscles, high fever, profuse sweating, or tremors;
  • Serious eye symptoms such as sudden vision loss, blurred vision, tunnel vision, eye pain or swelling, or seeing halos around lights;
  • Serious heart symptoms such as fast, irregular, or pounding heartbeats; fluttering in your chest; shortness of breath; sudden dizziness, lightheartedness, or passing out.

This is not a complete list of side effects and other serious side effects or health problems that may occur because of the use of this drug. Call your doctor for medical advice about serious side effects or adverse reactions. You may report side effects or health problems to FDA at 1-800-FDA-1088.


Lung cancer is a disease in which lung cells grow abnormally in an uncontrolled way. See Answer

What Other Drugs Interact with Gefitinib?

If your medical doctor is using this medicine to treat your pain, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider, or pharmacist first.

  • Gefitinib has no noted severe interactions with any other drugs.
  • Gefitinib has severe interactions with the following drugs
    • abametapir
    • alpelisib
    • apalutamide
    • fexinidazole
    • ivosidenib
    • ozanimod
    • palifermin
    • rimegepant
    • talazoparib
    • tucatinib
    • voxelotor
  • Gefitinib has moderate interactions with at least 85 other drugs.
  • Gefitinib has minor interactions with no other drugs.

This information does not contain all possible interactions or adverse effects. Visit the RxList Drug Interaction Checker for any drug interactions. Therefore, before using this product, tell your doctor or pharmacist about all your products. Keep a list of all your medications with you and share this information with your doctor and pharmacist. Check with your health care professional or doctor for additional medical advice, or if you have health questions or concerns.

What Are Warnings and Precautions for Gefitinib?


  • None

Effects of drug abuse

  • None

Short-Term Effects

  • See “What Are Side Effects Associated with Using Gefitinib?”

Long-Term Effects

  • See “What Are Side Effects Associated with Using Gefitinib?”


  • Interstitial lung disease (ILD) or ILD-like adverse drug reactions reported (.g, lung infiltration, pneumonitis, acute respiratory distress syndrome, or pulmonary fibrosis); permanently discontinue if confirmed
  • Increased ALT, AST, and bilirubin reported; obtain periodic liver function testing and withhold drug for worsening liver function or discontinue severe hepatic impairment
  • Gastrointestinal perforation reported; permanently discontinue
  • Severe or persistent diarrhea may occur; withhold drug for up to 14 days
  • Ocular disorders reported (e.g., keratitis, corneal erosion, aberrant eyelash growth, conjunctivitis, blepharitis, dry eye); interrupt or discontinue for severe, or worsening ocular disorders
  • Bullous conditions including toxic epidermal necrolysis, Stevens-Johnson syndrome, and erythema multiforme are reported rarely; discontinue the drug
  • Based on its mechanism of action and data from animal reproduction studies, gefitinib can cause fetal harm when administered to a pregnant woman (see Pregnancy)

Pregnancy & Lactation

  • Based on its mechanism of action and animal data, gefitinib can cause fetal harm when administered to a pregnant woman
  • Advise females of reproductive potential to use effective contraception during treatment with gefitinib and for at least 2 weeks following completion of therapy
  • Advise pregnant women of the potential hazard to a fetus or potential risk for loss of the pregnancy
  • Lactation
    • Unknown if distributed in human breast milk; not recommended
    • Consider the developmental and health benefits of breastfeeding along with the mother’s clinical need for the drug, and any potential adverse effects on the breastfed infant from the drug or the underlying maternal condition


Lung Cancer: Early Signs, Symptoms, Stages See Slideshow

Health Solutions From Our Sponsors