The short answer
Iron can reduce bictegravir absorption if taken together fasting. Biktarvy may be taken together with an iron supplement with food. The exact schedule matters when food is not available, particularly during pregnancy, so have your HIV pharmacist check the product and dose timing.
What this answer covers
Adult oral Biktarvy with iron supplements or iron-containing antacids. Direct evidence used ferrous fumarate 324 mg, approximately 107 mg elemental iron; the same measured effect is not assigned to every iron salt or dose.
- Supplement or preparation
- Iron
- Medication ingredient
- bictegravir
How much did iron affect absorption?
In a healthy-volunteer study, taking ferrous fumarate and Biktarvy together fasting reduced bictegravir exposure by about 63%. With a meal, the exposure ratio was about 84% of the reference value, which was Biktarvy taken alone fasting. The current label permits the fed combination. These concentration results do not tell us the probability of HIV treatment failure for an individual patient.
What is the recommended way to take them?
For Biktarvy, taking the iron product together with food is an allowed option. Routine simultaneous fasting use and taking Biktarvy two hours after iron are not recommended. During pregnancy, the label explicitly allows taking them together with food or, if fasting, taking Biktarvy at least two hours before or six hours after iron. Ask for a schedule that fits the reason you take iron.
Does the iron formulation matter?
The direct study used ferrous fumarate, not every iron formulation sold for anemia or included in prenatal vitamins. The amount printed as an iron salt is also different from its elemental iron content. The label gives practical instructions for iron products more broadly, but that does not make the measured 63% reduction a universal value. Multivitamins should be checked for additional minerals with their own instructions.
How can I keep both treatments on track?
Tell your HIV team why iron was prescribed, the full product name, daily amount and how you take it. A pharmacist can reconcile the iron plan with meals and Biktarvy without sacrificing either treatment. Continue your HIV medicine as prescribed and do not compensate by doubling a dose. Repeated fasting coadministration is a reason to review the schedule and consider whether routine viral-load monitoring needs attention.
Evidence and practical considerations
Absorption & effectiveness
Iron can reduce bictegravir absorption if taken together fasting. Biktarvy may be taken together with an iron supplement with food. The exact schedule matters when food is not available, particularly during pregnancy, so have your HIV pharmacist check the product and dose timing.
- Exact scope
- Adult oral Biktarvy with iron supplements or iron-containing antacids. Direct evidence used ferrous fumarate 324 mg, approximately 107 mg elemental iron; the same measured effect is not assigned to every iron salt or dose. 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 Biktarvy with ferrous fumarate under fasting and fed conditions; clinical HIV outcomes were not measured.
What remains uncertain
- One salt and dose in healthy volunteers. Food comparisons used a fasted-alone reference. Repeated dosing, all iron products and patients with altered absorption were not separately studied.
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 iron supplements or iron-containing antacids. Direct evidence used ferrous fumarate 324 mg, approximately 107 mg elemental iron; the same measured effect is not assigned to every iron salt or dose.
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 iron supplements or iron-containing antacids. Direct evidence used ferrous fumarate 324 mg, approximately 107 mg elemental iron; the same measured effect is not assigned to every iron salt or dose.
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 iron supplements or iron-containing antacids. Direct evidence used ferrous fumarate 324 mg, approximately 107 mg elemental iron; the same measured effect is not assigned to every iron salt or dose.
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: 75d47355782d3b3a
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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