The short answer
Magnesium-containing antacids are not recommended with raltegravir, even with staggered dosing. Nutritional magnesium supplements need a separate product and timing review. Do not assume that advice for a magnesium supplement makes an aluminum/magnesium antacid acceptable.
What this answer covers
Adult oral raltegravir tablets with magnesium-containing antacids or nutritional supplements. Direct trials tested magnesium hydroxide combined with aluminum hydroxide, not every magnesium glycinate, citrate or other stand-alone supplement.
- Supplement or preparation
- Magnesium
- Medication ingredient
- raltegravir
What is known about magnesium antacids?
A magnesium hydroxide and aluminum hydroxide antacid lowered raltegravir concentrations in human studies. The early single-dose 400 mg study found a lower 12-hour concentration despite unchanged overall exposure. Other studies and the current label reinforce concern about trough concentrations. These experiments assessed a combined antacid, so they do not tell us the isolated effect of magnesium or the effect of every supplement marketed for sleep or muscle symptoms.
Can I separate a magnesium antacid from raltegravir?
The label does not recommend aluminum/magnesium antacids with either adult raltegravir tablet regimen, including when dosing is staggered. Lower trough concentrations persisted in studied separation schedules. With 1,200 mg once-daily raltegravir, an antacid twelve hours later still substantially lowered the 24-hour concentration. A generic two-hour or six-hour gap should not replace this specific antacid recommendation.
Is a nutritional magnesium supplement different?
It may be a different formulation and dose, but magnesium can still raise a mineral-binding concern. NIH guidance for necessary polyvalent mineral supplements places raltegravir at least two hours before or six hours after and recommends virologic monitoring. UK specialist advice for 400 mg raltegravir uses a different supplement interval. These are guidance-based schedules, not proof that each magnesium salt has been tested or that the antacid warning no longer applies.
How do I get a workable plan?
Bring the magnesium label, its elemental amount and all other antacids, laxatives and supplements to your HIV pharmacist. The exact raltegravir formulation is important, particularly if you take two 600 mg tablets once daily. Keep the HIV treatment on its prescribed schedule and avoid self-directed dose changes. If a magnesium product has been used regularly alongside it, discuss whether the pattern warrants additional viral-load follow-up.
Evidence and practical considerations
Absorption & effectiveness
Magnesium-containing antacids are not recommended with raltegravir, even with staggered dosing. Nutritional magnesium supplements need a separate product and timing review. Do not assume that advice for a magnesium supplement makes an aluminum/magnesium antacid acceptable.
- Exact scope
- Adult oral raltegravir tablets with magnesium-containing antacids or nutritional supplements. Direct trials tested magnesium hydroxide combined with aluminum hydroxide, not every magnesium glycinate, citrate or other stand-alone supplement. 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
- Direct short antacid pharmacokinetic studies include single 400 mg and 1,200 mg regimen comparisons. Nutritional supplement guidance is based on potential mineral binding, not a retrieved trial of every magnesium salt.
What remains uncertain
- Aluminum/magnesium mixture data cannot isolate magnesium. Antacid avoidance and nutritional-supplement spacing are different recommendations; regional supplement intervals also differ. No measured effect is assigned to every magnesium preparation.
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 with magnesium-containing antacids or nutritional supplements. Direct trials tested magnesium hydroxide combined with aluminum hydroxide, not every magnesium glycinate, citrate or other stand-alone supplement.
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 with magnesium-containing antacids or nutritional supplements. Direct trials tested magnesium hydroxide combined with aluminum hydroxide, not every magnesium glycinate, citrate or other stand-alone supplement.
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 with magnesium-containing antacids or nutritional supplements. Direct trials tested magnesium hydroxide combined with aluminum hydroxide, not every magnesium glycinate, citrate or other stand-alone supplement.
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 with magnesium-containing antacids or nutritional supplements. Direct trials tested magnesium hydroxide combined with aluminum hydroxide, not every magnesium glycinate, citrate or other stand-alone supplement.
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.
Source 5: specialist pharmacy patient guidance
hivpa.org · Source check Sep 10, 2026
Population: People prescribed Isentress 400 mg twice daily; UK pharmacy guidance.
Advises avoiding aluminum/magnesium antacids, four-hour separation either side for calcium/magnesium supplements and multivitamins, and two-hour separation either side for iron/zinc.
How this applies: Documents a genuine guideline difference so an existing two-hour suggestion is not described as wholly invented. The consumer article states its U.S. NIH basis and directs regimen-specific reconciliation with the HIV pharmacist. Exact article scope: Adult oral raltegravir tablets with magnesium-containing antacids or nutritional supplements. Direct trials tested magnesium hydroxide combined with aluminum hydroxide, not every magnesium glycinate, citrate or other stand-alone supplement.
Patient guidance, not a comparative timing trial. The schedules differ from the U.S. NIH 2-hours-before/6-hours-after supplement recommendation. Its 400 mg scope does not establish instructions for Isentress HD 1,200 mg once daily. The 2026 URL folder is not the clinical review date.
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: 47c662ed83f6e375
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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Open the interaction checkerInformation, not medical advice. Do not change prescribed treatment based on this guide.