Medical Oncologist
Gefitinib (Iressa)
Taking Gefitinib: — Food, Timing and Missed Doses
Gefitinib is taken once a day, at the same time, with or without food. Knowing the routine — and what to do when it breaks — is the first thing to settle after your prescription is in hand.
Medically reviewed by Dr. T. Raghavender Reddy, Medical Oncologist, MBBS · DM (Medical Oncology) · MD (Radiation Oncology) · Last reviewed August 2026
- Once daily, same time — A consistent time each day keeps the drug at a steady level in your bloodstream.
- Food does not matter — You can take gefitinib with a meal or on an empty stomach — your choice.
- Missing a dose has a rule — Whether to take a late dose or skip it depends on how close your next dose is.
- Some medicines interfere — Several common medicines change how gefitinib works. Tell every doctor you see what you are on.
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Gefitinib is one tablet once a day, at the same time, with or without food. If you miss a dose and your next dose is not due soon, take it as soon as you remember. If the next dose is due shortly, skip it. Never take two tablets in one day.
How do you take gefitinib each day?
Pick a fixed time and keep it
Choose a time that fits your daily routine — morning with breakfast or evening before sleep. Taking it at the same time each day keeps the drug level steady. A phone alarm makes this easier.
Take it with or without food
Food does not significantly affect how gefitinib is absorbed. Take it whichever way feels most comfortable for you, and be consistent.
Swallow the tablet whole with water
If swallowing a tablet is difficult, disperse it in half a glass of plain water. Stir until dissolved, drink immediately, then rinse the glass with more water and drink that too so no dose is left behind.
Avoid grapefruit
Grapefruit and grapefruit juice raise gefitinib levels in the blood in a way that is not predictable. Avoid both while you are on this medicine.
Store tablets correctly
Keep tablets at room temperature, away from heat, moisture and direct sunlight. A bathroom cabinet is not ideal — the humidity there can affect the tablet.
Which medicines and foods can interfere with gefitinib?
Some medicines cause the body to break down gefitinib faster than intended, which can make it less effective. Medicines used to treat seizures, tuberculosis or HIV, and the herbal supplement St John's Wort, fall into this group. Tell your oncologist and pharmacist about everything you take.
Other medicines do the opposite — they slow how quickly the body clears gefitinib, which can raise its levels and increase the chance of side effects. Certain antifungal medicines, some antibiotics and some heart medicines can do this.
Antacids and medicines that reduce stomach acid — including omeprazole and similar tablets often prescribed for stomach protection — can reduce how much gefitinib is absorbed, because the drug needs an acidic environment to dissolve. If you take stomach medicines regularly, tell your team rather than managing the timing yourself.
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Your daily gefitinib routine
- Same time every day — set a phone reminder if it helps
- With food or without, whichever you prefer — be consistent
- No grapefruit or grapefruit juice
- Tell every prescribing doctor you are on gefitinib
- Bring your tablet pack to every oncology appointment
- Tell your team if you vomit after a dose — treat it as a missed tablet, not a reason to take another
What do you do if you miss a dose?
| Situation | What to do |
|---|---|
| You remember within a few hours of your usual time | Take the missed tablet now. Continue your normal schedule the next day. |
| Your next dose is due soon | Skip the missed tablet entirely. Take the next one at the usual time. Never take two in one day. |
| You vomited shortly after taking the tablet | Do not take another tablet. Treat it as a missed dose and take the next one at the usual time. Let your team know. |
| You are not sure which situation applies | Call your oncology team or pharmacist before taking anything extra. |
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Common questions
Frequently asked questions
Can I take gefitinib at night instead of in the morning?
Yes. The time of day matters less than consistency. Choose morning or evening based on what fits your routine best and you are least likely to forget. If you want to switch from one to the other after already starting, ask your team how to manage the transition so that two doses do not end up too close together.
What happens if I always take gefitinib with food?
That is fine. Food does not significantly affect how the drug is absorbed, so taking it with meals every day is a perfectly good routine. The important thing is being consistent. If you have been taking it with food, keep doing that rather than switching back and forth.
Is it safe to take gefitinib with antacids or stomach medicines?
It depends on the medicine and timing. Common antacids can reduce how much gefitinib is absorbed if taken at the same time, because gefitinib needs an acidic stomach environment to dissolve. Medicines that reduce stomach acid more durably — such as omeprazole — can have a similar effect when taken regularly. If you need stomach protection, tell your oncologist so they can advise on the right approach for you.
I vomited after taking my tablet. Should I take another one?
No. There is no reliable way to tell how much of the tablet was absorbed before you vomited, and taking another risks a double dose. Treat it as a missed tablet: take your next dose at the usual time and let your oncology team know it happened. If vomiting is frequent, your team may want to look at it as a side effect rather than a one-off.
Do I take gefitinib every day without breaks, or in cycles like chemotherapy?
Every day, continuously — there are no rest days built into the schedule the way chemotherapy cycles work. Taking it daily maintains a steady level in the bloodstream, which is how it acts against the cancer. Your team may recommend a temporary pause if a significant side effect develops, but that is a clinical decision for them to make. Do not stop or pause on your own without telling them first.