The short answer
Aluminum-containing antacids are not recommended with raltegravir, even when doses are staggered. This applies to both twice-daily Isentress and once-daily Isentress HD. Ask your HIV pharmacist to help choose an appropriate alternative rather than relying on a short dosing gap.
What this answer covers
Adult oral raltegravir tablets and aluminum-containing antacids. Direct studies used aluminum hydroxide combined with magnesium hydroxide; isolated nutritional aluminum exposure and pediatric formulations were not separately studied.
- Supplement or preparation
- Aluminum
- Medication ingredient
- raltegravir
What is the interaction?
Aluminum-containing antacids can interfere with raltegravir absorption through metal binding in the digestive tract. In an early study of a single 400 mg dose, the antacid lowered the 12-hour drug concentration even though total exposure was not significantly changed. Other label studies found reductions in both measures. These differences show why a single concentration result should not be treated as the whole clinical answer.
Can a longer gap prevent it?
The raltegravir label advises against aluminum/magnesium antacids even when doses are staggered. In studies of 400 mg twice-daily treatment, a six-hour gap still left lower trough concentrations. With the 1,200 mg once-daily regimen, an antacid twelve hours later also substantially lowered the 24-hour concentration. These findings do not support substituting a simple two-hour or six-hour rule for the recommendation to avoid the combination.
Does the type of Isentress matter?
For aluminum/magnesium antacids, the recommendation is to avoid coadministration with either adult tablet regimen. However, other antacids have different instructions: calcium carbonate is treated differently with 400 mg twice daily and 1,200 mg once daily. The tablet formulations are not interchangeable. A heartburn product’s full ingredient list and the exact Isentress dose are therefore both needed before selecting an alternative.
How should I handle heartburn treatment?
Show your pharmacist every antacid, stomach remedy and mineral product you take. They can distinguish the aluminum/magnesium products covered by this warning from other options and confirm the advice for your HIV regimen. Keep raltegravir on its prescribed schedule. If you have been taking the combination repeatedly, tell your HIV team so they can review exposure patterns, adherence and any needed viral-load monitoring.
Evidence and practical considerations
Absorption & effectiveness
Aluminum-containing antacids are not recommended with raltegravir, even when doses are staggered. This applies to both twice-daily Isentress and once-daily Isentress HD. Ask your HIV pharmacist to help choose an appropriate alternative rather than relying on a short dosing gap.
- Exact scope
- Adult oral raltegravir tablets and aluminum-containing antacids. Direct studies used aluminum hydroxide combined with magnesium hydroxide; isolated nutritional aluminum exposure and pediatric formulations were not separately studied. with Adult oral raltegravir tablets: Isentress 400 mg twice daily versus Isentress HD 1,200 mg once daily
- Medication form and route
- Adult oral raltegravir tablets: Isentress 400 mg twice daily versus Isentress HD 1,200 mg once daily; oral mineral, supplement or antacid within stated preparation scope
- Timing or duration
- Single-dose and short pharmacokinetic studies, including 400 mg and 1,200 mg regimens; spacing was tested from two to twelve hours under differing conditions.
What remains uncertain
- The combined antacid does not isolate aluminum. Concentration studies do not quantify the risk of virologic failure. Label advice to avoid antacid coadministration should not be generalized to normal dietary aluminum.
Factors that may matter: Exact mineral ingredients, preparation and elemental amount; Isentress 400 mg twice daily versus Isentress HD 1,200 mg once daily; Food and direction of administration when applicable; Concurrent mineral products, adherence and viral-load monitoring.
Read the supporting source summaries
Source 1: current manufacturer U.S. regulatory prescribing information
dailymed.nlm.nih.gov · Source check Sep 10, 2026
Population: People using oral raltegravir; adult 400 mg twice-daily Isentress and 1,200 mg once-daily Isentress HD regimens are distinguished.
Aluminum/magnesium antacids are not recommended even with staggered dosing. Calcium carbonate antacid requires no adjustment with 400 mg twice daily but is not recommended with 1,200 mg once daily. With the once-daily regimen, a 12-hour gap still left markedly reduced trough levels.
How this applies: Explicit salt-to-active-moiety bridge for exact RxNorm raltegravir. Each article preserves the 400 mg twice-daily versus 1,200 mg once-daily distinction and does not extend these tablet data to pediatric chewable tablets or suspension. Exact article scope: Adult oral raltegravir tablets and aluminum-containing antacids. Direct studies used aluminum hydroxide combined with magnesium hydroxide; isolated nutritional aluminum exposure and pediatric formulations were not separately studied.
The adult tablet regimens are not interchangeable. These exact antacid studies do not establish effects of all dietary mineral salts, zinc, iron or vitamin-only products. Healthy and HIV-positive study conditions differ; reductions in drug concentrations do not directly quantify treatment failures.
Source 2: U.S. expert clinical treatment guideline
clinicalinfo.hiv.gov · Source check Sep 10, 2026
Population: Adults and adolescents receiving integrase inhibitor regimens for HIV.
Bictegravir mineral directions depend on cation and food. If raltegravir must be used with polyvalent mineral supplements, give it at least 2 hours before or 6 hours after and monitor virologic response. Multivitamin chelation magnitude is uncertain. Raltegravir antacid rules are separate: avoid Al/Mg, and distinguish calcium carbonate 400 mg twice daily from 1,200 mg once daily. Do not coadminister bictegravir with St. John’s wort.
How this applies: Exact-drug management guidance. Bictegravir sodium and raltegravir potassium are interpreted through their labels’ active-moiety equivalents. Calcium/iron food exceptions for bictegravir do not transfer to raltegravir. Exact article scope: Adult oral raltegravir tablets and aluminum-containing antacids. Direct studies used aluminum hydroxide combined with magnesium hydroxide; isolated nutritional aluminum exposure and pediatric formulations were not separately studied.
Expert recommendations include predicted interactions where exact-pair clinical studies are absent. A suggested supplement schedule does not supersede the distinct antacid avoidance instructions. No universal safe dose or virologic risk percentage is established.
Source 3: peer-reviewed prospective human pharmacokinetic study
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: 20 adults with HIV already receiving raltegravir in a fixed-sequence pharmacokinetic study; 19 evaluable for several comparisons.
Simultaneous calcium carbonate reduced exposure to 28% and 24-hour concentration to 52% of reference. Twelve-hour-separated calcium carbonate preserved overall exposure but reduced 24-hour concentration to 43%; separated Al/Mg reduced that concentration to 42%.
How this applies: Exact raltegravir with specified antacids under adult once-daily conditions. Combined Al/Mg cannot distinguish the individual ion’s contribution. Exact article scope: Adult oral raltegravir tablets and aluminum-containing antacids. Direct studies used aluminum hydroxide combined with magnesium hydroxide; isolated nutritional aluminum exposure and pediatric formulations were not separately studied.
Original abstract was read; full journal text was not retrieved. Drug concentration endpoints, not virologic failure rates. This 1,200 mg once-daily result cannot be directly assigned to the 400 mg twice-daily formulation or to every nutritional mineral product.
Source 4: peer-reviewed prospective human pharmacokinetic study
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: 12 healthy HIV-seronegative volunteers in a randomized crossover study.
The 12-hour raltegravir concentration was 67% lower with antacid, although overall exposure and peak concentration were not significantly changed.
How this applies: Exact raltegravir-antacid evidence. The preserved total exposure does not negate the lower trough or the label’s antacid recommendation; it does not test isolated nutritional aluminum or magnesium. Exact article scope: Adult oral raltegravir tablets and aluminum-containing antacids. Direct studies used aluminum hydroxide combined with magnesium hydroxide; isolated nutritional aluminum exposure and pediatric formulations were not separately studied.
Full-text retrieval attempt failed; only the original abstract was assessed. Single-dose healthy study, not chronic treatment or a clinical efficacy trial. Different exposure patterns from current label studies are preserved rather than described as uniform across all conditions.
Research assessment: · Open full citations ↗
Review and change history
- Publication status
- Published research summary
- Clinical review
- Not yet recorded
| Date | Update |
|---|---|
| Article prepared | |
| Current exact-drug labeling and guidance checked; original human studies and neutral findings assessed. Current statements adjudicated with formulation, food and directional timing corrections. Article written; clinical sign-off not recorded. | |
| Research summary published |
Article revision: 3fda6093f94771dd
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.
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