The short answer
Aluminum hydroxide antacids can lower diflunisal exposure, especially under some fasting conditions. Ask your pharmacist about the exact antacid and schedule; an all-aluminum avoidance or fixed-spacing rule is not established.
What this answer covers
Oral aluminum-containing products with prescription oral diflunisal. Direct evidence is for aluminum hydroxide antacids, not every aluminum salt or exposure.
- Supplement or preparation
- Aluminum
- Medication ingredient
- diflunisal
The interaction was measured with an antacid
One original study found approximately 40% lower diflunisal bioavailability with aluminum hydroxide. A second small study found a 26% decrease in total exposure under fasting conditions. These are drug-level findings for aluminum hydroxide antacid, not proof that every aluminum-containing product reduces pain relief.
Meal and formulation conditions changed the result
In the second study, aluminum hydroxide and an aluminum/magnesium mixture had no detectable effect under the tested fed conditions. Magnesium hydroxide taken fasting behaved differently. These small single-dose results explain why the antacid name and instructions matter, but do not establish a universal meal-based solution.
Ask about repeated antacid use
Diflunisal labeling warns that continuous antacid use may reduce drug levels more importantly than occasional use. Tell your pharmacist which antacid you take, how often and whether it is taken with food. Do not increase diflunisal yourself if pain control seems worse.
Get an individualized timing plan
The inspected studies do not establish a fixed number of hours that reliably prevents the interaction. Your pharmacist can assess the exact formulation and regimen. Persistent indigestion or stomach pain during diflunisal treatment also deserves medical review rather than simply increasing antacid use.
Evidence and practical considerations
Absorption & effectiveness
Aluminum hydroxide antacids can reduce diflunisal exposure under some dosing conditions.
- Exact scope
- Oral aluminum-containing products with prescription oral diflunisal. Direct evidence is for aluminum hydroxide antacids, not every aluminum salt or exposure. with Exact diflunisal RxCUI 3393 IN, confirmed by current RxNorm. Prescription oral tablets; not aspirin, and not a class-average NSAID effect.
- Medication form and route
- Oral
What remains uncertain
- Small healthy-volunteer studies; effects depended on fasting/fed conditions. No tested hours-apart remedy, no all-aluminum equivalence.
Factors that may matter: Exact preparation and dose; Fasting versus fed dosing; Bleeding and ulcer history; Other medicines.
Read the supporting source summaries
Source 1: Current prescribing information
dailymed.nlm.nih.gov · Source check Sep 10, 2026
Population: Prescription oral diflunisal users and healthy-volunteer pharmacology studies.
Diflunisal has dose-dependent reversible platelet effects. At 500 mg twice daily effects were slight; 250 mg twice daily had no measurable effect in a short study. Serious GI bleeding and ulcers remain labeled risks. Antacids may lower levels, especially with continuous use.
How this applies: Exact current drug label. Exact diflunisal RxCUI 3393 IN, confirmed by current RxNorm. Prescription oral tablets; not aspirin, and not a class-average NSAID effect.
Not proof of each supplement combination. Short healthy-volunteer fecal blood-loss findings do not establish long-term GI safety. Aspirin has different platelet pharmacology. No universal antacid separation interval.
Source 2: Original clinical research
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: Healthy volunteers.
Relative exposure was 0.60 by plasma AUC and 0.63 by urinary recovery, indicating approximately 40% lower bioavailability.
How this applies: Exact drug where specified; other-drug and supplement-only findings remain indirect.
Abstract-only; fullTextXML failed. Exact aluminum hydroxide, not all aluminum salts or calcium carbonate. No tested separation interval.
Source 3: Original clinical research
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: 12 healthy men.
Fasting aluminum hydroxide lowered AUC 26% and peak 46%. Fed aluminum hydroxide or the tested fed aluminum/magnesium mixture had no detectable effect. Fasting magnesium hydroxide increased early concentrations and AUC by 10%.
How this applies: Exact drug where specified; other-drug and supplement-only findings remain indirect.
Abstract-only, single doses and small sample. Not calcium carbonate. No long-term pain endpoint or trial of hours-apart dosing.
Source 4: Medication terminology
rxnav.nlm.nih.gov · Source check Sep 10, 2026
Population: Terminology record.
Diflunisal, IN.
How this applies: Exact identity.
No clinical evidence.
Research assessment: · Open full citations ↗
Timing & monitoring
A universal rule to separate or avoid every aluminum product with diflunisal has not been established.
- Exact scope
- Oral aluminum-containing products with prescription oral diflunisal. Direct evidence is for aluminum hydroxide antacids, not every aluminum salt or exposure. with Exact diflunisal RxCUI 3393 IN, confirmed by current RxNorm. Prescription oral tablets; not aspirin, and not a class-average NSAID effect.
- Medication form and route
- Oral
What remains uncertain
- The tested formulations and meal conditions differ; fixed separation intervals were not evaluated.
Factors that may matter: Exact preparation and dose; Fasting versus fed dosing; Bleeding and ulcer history; Other medicines.
Read the supporting source summaries
Source 1: Current prescribing information
dailymed.nlm.nih.gov · Source check Sep 10, 2026
Population: Prescription oral diflunisal users and healthy-volunteer pharmacology studies.
Diflunisal has dose-dependent reversible platelet effects. At 500 mg twice daily effects were slight; 250 mg twice daily had no measurable effect in a short study. Serious GI bleeding and ulcers remain labeled risks. Antacids may lower levels, especially with continuous use.
How this applies: Exact current drug label. Exact diflunisal RxCUI 3393 IN, confirmed by current RxNorm. Prescription oral tablets; not aspirin, and not a class-average NSAID effect.
Not proof of each supplement combination. Short healthy-volunteer fecal blood-loss findings do not establish long-term GI safety. Aspirin has different platelet pharmacology. No universal antacid separation interval.
Source 2: Original clinical research
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: 12 healthy men.
Fasting aluminum hydroxide lowered AUC 26% and peak 46%. Fed aluminum hydroxide or the tested fed aluminum/magnesium mixture had no detectable effect. Fasting magnesium hydroxide increased early concentrations and AUC by 10%.
How this applies: Exact drug where specified; other-drug and supplement-only findings remain indirect.
Abstract-only, single doses and small sample. Not calcium carbonate. No long-term pain endpoint or trial of hours-apart dosing.
Research assessment: · Open full citations ↗
Review and change history
- Publication status
- Published research summary
- Clinical review
- Not yet recorded
| Date | Update |
|---|---|
| Article prepared | |
| Sources checked and article drafted. | |
| Research summary published |
Article revision: 5a3d079c659bb7d9
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.