The short answer
Have your transplant team check an aluminum-containing antacid before you use it. The clearest evidence concerns a product combining aluminum and magnesium hydroxide, which changed tacrolimus exposure. A routine spacing rule has not been established.
What this answer covers
This advice concerns oral tacrolimus and aluminum hydroxide antacids. The measured interaction involved combined magnesium and aluminum hydroxide, so it does not give an effect size for aluminum hydroxide alone.
- Supplement or preparation
- Aluminum hydroxide
- Medication ingredient
- tacrolimus
What changed in the antacid study?
The PROGRAF label describes a single-dose study in healthy volunteers. Combined magnesium and aluminum hydroxide raised total tacrolimus exposure by 21%, while lowering its peak concentration by 10%. A lower peak therefore does not mean the overall interaction is harmless.
Does this prove a heart-rhythm problem?
The label warns that this combination may raise tacrolimus levels and increase serious adverse effects, including QT prolongation. The study summary does not report how often arrhythmias occurred. Existing heart-rhythm problems and other medicines can affect the importance of the warning.
Will taking the antacid later solve it?
The inspected label recommends checking tacrolimus levels and adjusting the prescription if needed. It does not establish a safe number of hours between these products. Ask the transplant pharmacist to review the actual antacid and your dosing schedule before changing either.
What should I show my care team?
Bring the ingredient list, strength, amount used and how often you take the antacid. A mixed magnesium-aluminum product differs from aluminum hydroxide alone or a nutritional magnesium supplement. Starting or stopping regular use may change the monitoring plan; keep taking tacrolimus as prescribed.
Evidence and practical considerations
Timing & monitoring
A combined magnesium-aluminum-hydroxide antacid altered oral tacrolimus exposure; isolated aluminum and a safe spacing interval remain unquantified.
- Exact scope
- Combined magnesium and aluminum hydroxide antacid; no isolated-aluminum effect size. with Tacrolimus, exact RxCUI 42316, inventory name tacrolimus, TTY IN. Oral systemic tacrolimus only. The US PROGRAF label describes tacrolimus capsules and anhydrous-equivalent strength; the UK capsule SmPC section 2 explicitly states tacrolimus as monohydrate. This bridges labeled monohydrate capsules to the IN, without merging different release formulations or transferring exposure results to topical or intravenous tacrolimus. No cyclosporine or other immunosuppressant evidence is substituted for tacrolimus evidence.
- Medication form and route
- oral
What remains uncertain
- Healthy single-dose study summarized in label; formulation and dose details limited.
Read the supporting source summaries
Source 1: regulatory prescribing information with original human pharmacokinetic study summary
dailymed.nlm.nih.gov · Source check Sep 10, 2026
Population: Healthy volunteers in the single-dose combined-antacid pharmacokinetic study summarized by the label; systemic oral tacrolimus users for the surrounding monitoring and toxicity guidance.
Mean total tacrolimus exposure increased 21%, while mean peak concentration decreased 10%. The interaction table advises trough monitoring and dose reduction if needed, with potential neurotoxicity and QT risk. The same label calls for individualized dosing and drug-level monitoring; its oral formulations are not freely interchangeable.
How this applies: Direct for the combined antacid named in the current claims. Only conditional applicability to this Aluminum hydroxide record; not evidence for every aluminum salt or magnesium supplement. The surrounding monitoring guidance concerns the same exact oral medicine; topical tacrolimus is excluded. All cited sections belong to one label, counted as one source.
No isolated-aluminum estimate or measured arrhythmia incidence. Total exposure and peak concentration move in different directions. No controlled dose-separation schedule is supplied. General toxicity warnings are not a second independent study and do not establish a clinical-event rate from this antacid.
Research assessment: · Open full citations ↗
Side effects & toxicity
The label links exposure-raising antacids to potential tacrolimus adverse effects including QT prolongation, without a measured pair-specific arrhythmia rate.
- Exact scope
- Combined magnesium-aluminum-hydroxide antacid. with Tacrolimus, exact RxCUI 42316, inventory name tacrolimus, TTY IN. Oral systemic tacrolimus only. The US PROGRAF label describes tacrolimus capsules and anhydrous-equivalent strength; the UK capsule SmPC section 2 explicitly states tacrolimus as monohydrate. This bridges labeled monohydrate capsules to the IN, without merging different release formulations or transferring exposure results to topical or intravenous tacrolimus. No cyclosporine or other immunosuppressant evidence is substituted for tacrolimus evidence.
- Medication form and route
- oral
What remains uncertain
- Potential clinical risk is a label precaution, not an observed arrhythmia trial result.
Read the supporting source summaries
Source 1: regulatory prescribing information with original human pharmacokinetic study summary
dailymed.nlm.nih.gov · Source check Sep 10, 2026
Population: Healthy volunteers in the single-dose combined-antacid pharmacokinetic study summarized by the label; systemic oral tacrolimus users for the surrounding monitoring and toxicity guidance.
Mean total tacrolimus exposure increased 21%, while mean peak concentration decreased 10%. The interaction table advises trough monitoring and dose reduction if needed, with potential neurotoxicity and QT risk. The same label calls for individualized dosing and drug-level monitoring; its oral formulations are not freely interchangeable.
How this applies: Direct for the combined antacid named in the current claims. Only conditional applicability to this Aluminum hydroxide record; not evidence for every aluminum salt or magnesium supplement. The surrounding monitoring guidance concerns the same exact oral medicine; topical tacrolimus is excluded. All cited sections belong to one label, counted as one source.
No isolated-aluminum estimate or measured arrhythmia incidence. Total exposure and peak concentration move in different directions. No controlled dose-separation schedule is supplied. General toxicity warnings are not a second independent study and do not establish a clinical-event rate from this antacid.
Research assessment: · Open full citations ↗
Review and change history
- Publication status
- Published research summary
- Clinical review
- Not yet recorded
| Date | Update |
|---|---|
| Article prepared | |
| Original evidence and current product information inspected; article distinguishes observed results, product limits and remaining uncertainty. | |
| Research summary published |
Article revision: 73f3838bb5a2aa6c
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.