Iressa (gefitinib)

Reviewed by: HU Medical Review Board | Last reviewed: September 2023

Iressa® (gefitinib) is a targeted therapy that is used to treat people with non-small cell lung cancer (NSCLC) that has:1

  • Epidermal growth factor receptor (EGFR) genes with the exon 19 deletion or exon 21 (L858R) substitution mutation,
  • Spread to other parts of the body (metastatic), and
  • Not been previously treated for metastatic lung cancer

Your doctor will perform a genetic test to find out whether your cancer is positive for EGFR genes. About 10 to 15 percent of people with lung cancer are EGFR-positive. People with this type of lung cancer tend to have no smoking history.1,2

What are the ingredients in Iressa?

The active ingredient in Iressa is gefitinib.1

How does Iressa work?

Iressa is designed to block the activating sites (tyrosine kinases) of several proteins in cancer cells. These proteins can stimulate cancer growth when the tumor has an EGFR mutation. By blocking the action of the proteins, Iressa may shrink the cancer or slow down its growth.1

What are the possible side effects?

The most common side effects of Iressa include:1

  • Skin reactions, such as redness, rash, itching, and acne
  • Diarrhea

These are not all the possible side effects of Iressa. Talk to your doctor about what to expect when taking Iressa. You also should call your doctor if you have any changes that concern you when taking Iressa.

Other things to know

Before starting treatment with Iressa, tell your doctor if you have:1

  • Lung or breathing problems
  • A history of liver problems
  • Vision or eye problems

Iressa can harm an unborn baby. If you can become pregnant, you should use birth control during treatment and for some time after the last dose of Iressa. You should also not breastfeed during treatment with Iressa and for some time after the last dose. Talk to your doctor about your options for birth control and breastfeeding while taking Iressa.1

Your doctor will do blood tests to check your liver function during treatment with Iressa.1

If you take a blood thinner called warfarin, your doctor should do blood tests regularly to check how fast your blood clots during treatment with Iressa.1

If you take a proton pump inhibitor (PPI), H2 blocker, or an antacid medicine, talk to your doctor about the best time to take it during treatment with Iressa.1

Before beginning treatment for lung cancer, tell your doctor about all your health conditions and any other drugs, vitamins, or supplements you are taking. This includes over-the-counter drugs.

For more information, read the full prescribing information of Iressa.

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