The short answer
Magnesium matters when used as an antacid. Keep it at least six hours before or after gefitinib according to the oral product instructions, and confirm the actual formulation with the pharmacist.
What this answer covers
Oral gefitinib and magnesium in an acid-neutralizing antacid. Nutritional salts without equivalent antacid activity are not automatically the same exposure.
- Supplement or preparation
- Magnesium
- 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.
Identify the product’s purpose
The concern is reduced drug availability when an antacid changes the stomach environment. Magnesium on a nutrition label alone does not establish an antacid dose or acid-neutralizing effect. Check the salt, strength and whether it is sold for indigestion, mineral replacement or another purpose.
What the original study measured
A volunteer study used sustained elevated stomach pH with high-dose acid suppression and found roughly half the total gefitinib exposure. That experiment supports pH sensitivity, but is not a salt-by-salt trial of aluminum, calcium carbonate or magnesium supplements.
Keep the timing and formulation together
For these oral gefitinib tablets, use the six-hour interval on either side of an antacid. Other acid-reducing medicines have their own directions, so ask the pharmacist to check the full schedule. Do not raise the dose to compensate for an assumed absorption problem.
Evidence and practical considerations
Timing & monitoring
The current exact oral instructions support a preparation-specific antacid interval rather than a blanket interaction with every mineral supplement.
- Exact scope
- Oral gefitinib and magnesium in an acid-neutralizing antacid. Nutritional salts without equivalent antacid activity are not automatically the same exposure. 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
- Exact oral antacid instruction; no universal mineral binding effect or salt-specific cancer-outcome evidence.
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: 26 healthy men in randomized crossover.
AUC decreased 47% and peak concentration 71%; no serious adverse events.
How this applies: Exact reported preparation, population and endpoints; transfer to gefitinib explicitly limited.
Abstract-only sustained acid suppression, not each mineral salt or clinical cancer-control outcome.
Source 3: 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: 8ebcc02dc7fa1dea
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.