The short answer
Magnesium-containing antacids can substantially reduce bictegravir absorption. Take Biktarvy at least 2 hours before or 6 hours after an aluminum/magnesium antacid. Magnesium supplements also need a timing review, but the direct antacid results do not establish the same effect for every magnesium preparation.
What this answer covers
Adult oral Biktarvy with magnesium-containing antacids or nutritional supplements. Direct evidence used magnesium hydroxide combined with aluminum hydroxide; magnesium glycinate, citrate and other stand-alone supplements were not separately tested.
- Supplement or preparation
- Magnesium
- Medication ingredient
- bictegravir
Why are magnesium products a concern?
Magnesium ions can bind integrase inhibitors in the digestive tract. In a Biktarvy study, an antacid containing magnesium hydroxide plus aluminum hydroxide markedly reduced bictegravir exposure when taken together fasting. Because both antacid ingredients were present, the study cannot separate their contributions. It also does not establish a numerical effect for magnesium glycinate, magnesium citrate or every nutritional supplement.
Is a two-hour gap enough?
The order matters. For an aluminum/magnesium antacid, the current U.S. label requires Biktarvy at least two hours before or six hours after. In the study, Biktarvy two hours after the antacid still had substantially reduced exposure. Taking the antacid with food did not eliminate the interaction either. Avoid turning “two hours apart” into a rule that works equally well in both directions.
What about magnesium for sleep, cramps or nutrition?
A nutritional magnesium product may differ from the antacid tested, but its purpose does not remove the need to check mineral binding. NIH guidance includes magnesium among polyvalent mineral supplements that require attention with integrase inhibitors. Have your pharmacist check the salt, elemental amount and other ingredients. Do not assume the calcium-and-iron food exception for Biktarvy automatically covers a magnesium supplement.
What should I do if I already take both?
Write down when you take Biktarvy, meals and each magnesium-containing product, including laxatives or heartburn remedies. Your HIV pharmacist can identify which instructions apply and arrange a practical schedule. Keep taking Biktarvy as prescribed. If you have repeatedly combined it with a mineral product, tell your HIV team; they can review the pattern and decide whether additional viral-load follow-up is appropriate.
Evidence and practical considerations
Absorption & effectiveness
Magnesium-containing antacids can substantially reduce bictegravir absorption. Take Biktarvy at least 2 hours before or 6 hours after an aluminum/magnesium antacid. Magnesium supplements also need a timing review, but the direct antacid results do not establish the same effect for every magnesium preparation.
- Exact scope
- Adult oral Biktarvy with magnesium-containing antacids or nutritional supplements. Direct evidence used magnesium hydroxide combined with aluminum hydroxide; magnesium glycinate, citrate and other stand-alone supplements were not separately tested. with Adult oral bictegravir as Biktarvy 50/200/25 mg fixed combination
- Medication form and route
- Adult oral bictegravir as Biktarvy 50/200/25 mg fixed combination; oral mineral, supplement or antacid within stated preparation scope
- Timing or duration
- Single-dose study of simultaneous, spaced and fed combined antacid exposure. No exact chronic magnesium glycinate or citrate trial was identified.
What remains uncertain
- Direct combined-antacid evidence does not isolate magnesium or quantify each nutritional salt. A generic two-hour gap in either direction is not supported. Food does not remove the combined Al/Mg antacid effect.
Factors that may matter: Exact mineral ingredients, preparation and elemental amount; Biktarvy fixed-combination formulation; Food and direction of administration when applicable; Concurrent mineral products, adherence and viral-load monitoring.
Read the supporting source summaries
Source 1: current U.S. regulatory prescribing information
dailymed.nlm.nih.gov · Source check Sep 10, 2026
Population: People using the fixed combination Biktarvy for HIV treatment; adult-strength tablets contain bictegravir 50 mg, emtricitabine 200 mg and tenofovir alafenamide 25 mg.
Give Biktarvy at least 2 hours before or 6 hours after aluminum/magnesium antacids. Calcium or iron can be taken together with food; routine simultaneous fasting administration or Biktarvy 2 hours after calcium/iron is not recommended. St. John’s wort coadministration is not recommended because bictegravir and tenofovir alafenamide may decrease.
How this applies: Exact bictegravir active ingredient is bridged from bictegravir sodium by the label’s declared equivalent dose. Cation findings concern bictegravir; St. John’s wort can also affect the tenofovir alafenamide component. No emtricitabine interaction is inferred. Exact article scope: Adult oral Biktarvy with magnesium-containing antacids or nutritional supplements. Direct evidence used magnesium hydroxide combined with aluminum hydroxide; magnesium glycinate, citrate and other stand-alone supplements were not separately tested.
Combination-product labeling, not evidence for bictegravir monotherapy. Named antacid directions are not direct experiments on every nutritional magnesium/aluminum formulation. The label supplies no echinacea trial or measured interaction for every multivitamin. Pregnancy has explicit additional fasting instructions.
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 Biktarvy with magnesium-containing antacids or nutritional supplements. Direct evidence used magnesium hydroxide combined with aluminum hydroxide; magnesium glycinate, citrate and other stand-alone supplements were not separately tested.
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
europepmc.org · Source check Sep 10, 2026
Population: 42 healthy HIV-negative adults aged 18-45 years, in three cohorts of 14; open-label single-dose study conducted in 2016.
Fasted simultaneous bictegravir exposure was lower by 79% with combined Al/Mg antacid, 33% with calcium carbonate and 63% with ferrous fumarate. Bictegravir 2 hours before Al/Mg largely preserved exposure; 2 hours after still reduced it by 52%. With food, calcium exposure ratio was 1.033 and iron ratio 0.838 relative to bictegravir alone fasting; Al/Mg still reduced exposure by 47%.
How this applies: Direct preparation-specific evidence for adult oral bictegravir in Biktarvy. Calcium carbonate and ferrous fumarate findings are explicitly bounded within broader calcium and iron articles. These data do not directly measure every multivitamin, magnesium chelate or aluminum product. Exact article scope: Adult oral Biktarvy with magnesium-containing antacids or nutritional supplements. Direct evidence used magnesium hydroxide combined with aluminum hydroxide; magnesium glycinate, citrate and other stand-alone supplements were not separately tested.
Single doses in healthy people, not a clinical failure trial. Combined Al/Mg does not isolate either ion. Fed combination arms were compared with a fasted-alone reference, not fed-alone control. Sponsor Gilead participated in design, analysis and writing. Discussion language about regional timing differs from the current U.S. label; the U.S. 2-before/6-after antacid instructions govern the article.
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: c97e7585f78562ce
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.