Generic Name Brand Name
gefitinib Iressa

How It Works

Gefitinib is an epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TK) that blocks growth factors that allow some tumors to grow. Gefitinib is a medication that is taken by mouth (oral).

Why It Is Used

Gefitinib is used to shrink tumors that have progressed after initial chemotherapy treatment. This is called a third-line treatment and is used for people who have advanced disease without many treatment options. Gefitinib is used to treat non–small cell lung cancer but is currently recommended only for people who are already doing well on this drug.

How Well It Works

Gefitinib appears to shrink the tumor and reduce symptoms. It appears to work better in women than in men and better in nonsmokers who have lung cancer.

Recent studies have shown that gefitinib may not have a long-term survival benefit for many people. The U.S. Food and Drug Administration (FDA) advises people who are using this medication to continue their treatment and talk with their oncologist.1

Side Effects

Possible serious side effects of gefitinib include:

  • Allergic reactions. Signs of allergic reaction can include trouble breathing; swelling or closing of the throat; swollen face, tongue, or lips; or hives.
  • Eye pain or irritation.
  • Severe or ongoing nausea, vomiting, or diarrhea.
  • Changes in liver function.

A rare side effect of gefitinib is interstitial lung disease, which causes shortness of breath, cough, and fever.

Less serious side effects may include:

  • Mild rash or acne.
  • Diarrhea.
  • Nausea and vomiting (rare).
  • Feeling of weakness.
  • Dry skin and itching.

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

What To Think About

Gefitinib should be administered only under the supervision of a medical oncologist.

The U.S. Food and Drug Administration (FDA) is now recommending that gefitinib only be taken by people who are already on the drug and whose doctors believe it is helping. Other drugs seem to have a better chance of helping people who have lung cancer live longer. For more information, visit

Gefitinib can cause birth defects. Do not use this medication if you are pregnant or wish to become pregnant or father a child while you are taking it.

Do not use this medication if you have liver disease.

Be sure to tell your doctor if you are taking any of the following medications that may change the effectiveness of gefitinib:

  • Itraconazole (Sporanox)
  • Ketoconazole (Nizoral)
  • Phenytoin (Dilantin)
  • Ranitidine (Zantac) or cimetidine (Tagamet)
  • Rifampin (Rifadin)
  • Warfarin (Coumadin)

Complete the new medication information form (PDF)(What is a PDF document?) to help you understand this medication.



  1. U.S. Food and Drug Administration (2004). FDA statement on Iressa. FDA Public Health Web Notification. Available online:

Other Works Consulted

  • Abramowicz M (2003). Treatment guidelines: Drugs of choice for cancer. Medical Letter on Drugs and Therapeutics, 1(7): 41–52.

Last Updated: June 4, 2008

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