The short answer
Have green tea extract reviewed before taking it with gefitinib. Concentrated extracts have caused liver-enzyme elevations in a human trial, but a change in gefitinib absorption or effectiveness has not been established.
What this answer covers
Concentrated Camellia sinensis leaf extracts with oral gefitinib; EGCG dose, duration and formulation distinguished from brewed tea.
- Supplement or preparation
- Camellia Sinensis Leaf Extract
- Medication ingredient
- gefitinib
Check the exact treatment
This review concerns oral gefitinib tablets used for selected EGFR-mutated lung cancers. The prescribed tablet and dosing plan matter. Follow the cancer team’s instructions; food, acid reducers and supplements should be reviewed together.
The liver signal concerns concentrated extract
In a year-long placebo-controlled study, an extract supplying 843 mg EGCG daily caused more ALT elevations than placebo. Overall adverse-event and serious-event frequencies were not significantly different. The participants were postmenopausal women, not patients receiving gefitinib, so this cannot quantify a combined risk.
An enzyme theory is not a measured drug interaction
A small two-week study of a decaffeinated green tea extract found no significant changes in CYP3A4 or CYP2D6 probe-drug measures. It did not test gefitinib or prove long-term liver safety. Laboratory cancer-cell findings also cannot establish improved or reduced gefitinib effectiveness in people.
Bring the extract label to the team
Report the EGCG amount, dose and other ingredients, and follow gefitinib’s liver-testing plan. Do not use the extract to boost cancer treatment or assume a time gap prevents liver injury. Promptly report yellowing skin or eyes, dark urine or persistent loss of appetite.
Evidence and practical considerations
Side effects & toxicity
A conditional liver-risk precaution is supported; the vague claim of changed gefitinib effectiveness is not supported by the checked human evidence.
- Exact scope
- Concentrated Camellia sinensis leaf extracts with oral gefitinib; EGCG dose, duration and formulation distinguished from brewed tea. with RxNorm 328134 IN gefitinib. Current exact oral product: Gefitinib oral tablets. Salt/formulation named explicitly; no transfer to unrelated drugs or routes.
- Medication form and route
- Oral
What remains uncertain
- No exact gefitinib-extract clinical trial or PK measurement. Separate liver signal and CYP-probe null findings retained; product mass is not EGCG dose.
Factors that may matter: Exact oral formulation and supplement preparation; Drug exposure versus clinical outcomes; Dose, duration and other medicines; Individual monitoring plan.
Read the supporting source summaries
Source 1: Current original prescribing information
dailymed.nlm.nih.gov · Source check Sep 10, 2026
Population: Patients prescribed the exact oral formulation.
Six-hour antacid separation; CYP3A induction can lower exposure; periodic liver monitoring.
How this applies: RxNorm 328134 IN gefitinib. Current exact oral product: Gefitinib oral tablets. Salt/formulation named explicitly; no transfer to unrelated drugs or routes.
Exact current oral product source, not a clinical trial of every supplement. Formulation, dose, population and mechanism remain explicit.
Source 2: Original clinical research
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: 1075 postmenopausal women randomized.
ALT elevations 6.7% versus 0.7%; overall adverse and serious adverse event frequencies not significantly different.
How this applies: Exact reported preparation, population and endpoints; transfer to gefitinib explicitly limited.
Abstract-only; original body challenge retained. Not gefitinib co-use, every extract or brewed tea. Biomarker injury signal does not measure combined liver failure risk.
Source 3: Original clinical research
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: 11 healthy volunteers.
No significant CYP3A4/2D6 probe changes.
How this applies: Exact reported preparation, population and endpoints; transfer to gefitinib explicitly limited.
Abstract-only small short probe study, not gefitinib exposure or long-term liver safety.
Source 4: Medication terminology
rxnav.nlm.nih.gov · Source check Sep 10, 2026
Population: Terminology.
gefitinib is IN.
How this applies: Exact ingredient.
Not clinical evidence.
Research assessment: · Open full citations ↗
Review and change history
- Publication status
- Published research summary
- Clinical review
- Not yet recorded
| Date | Update |
|---|---|
| Research summary published | |
| Article prepared | |
| Sources checked and article drafted. |
Article revision: 572055c8b2664e99
This guide brings together the evidence records used by our interaction checker. Each finding retains its own preparation limits, research date, and source summaries.
Full citations require verification. Reading this answer and the source summaries does not.
Taking other supplements or medications?
Use the checker to explore your other combinations. Ask a pharmacist to review the exact products, amounts and medical conditions in your complete list.
Open the interaction checkerInformation, not medical advice. Do not change prescribed treatment based on this guide.