The short answer
Yes, magnesium products reduce eltrombopag absorption, and the label says to take eltrombopag at least 2 hours before or 4 hours after them. An antacid containing magnesium carbonate and aluminum hydroxide cut eltrombopag exposure by about 70% in healthy volunteers. Magnesium supplements such as magnesium oxide or citrate were not tested, but the label applies the same rule to every magnesium-containing supplement, antacid or laxative.
What this answer covers
Magnesium supplements (oxide, citrate, chloride, glycinate and other salts), magnesium-containing antacids and laxatives, and magnesium in multivitamins, with eltrombopag tablets or oral suspension.
- Supplement or preparation
- magnesium
- Medication ingredient
- eltrombopag
What the label establishes
Eltrombopag chelates polyvalent cations, and magnesium is named among them. The label directs patients to take eltrombopag at least 2 hours before or 4 hours after antacids, mineral supplements and other magnesium-containing products, and the ALVAIZ label repeats the same wording.
The study behind the warning
In 26 healthy adults, a single 75 mg eltrombopag dose taken with an antacid providing 1,425 mg magnesium carbonate and 1,524 mg aluminum hydroxide reduced total exposure and peak level by about 70%. The antacid also contained sodium alginate, whose contribution the label calls unknown, so the result cannot be attributed to magnesium alone.
Which magnesium products this covers
Magnesium supplements are sold as oxide, citrate, chloride and other salts, and magnesium is also the active ingredient of many antacids and laxatives. Only the carbonate antacid was tested, but chelation depends on the magnesium ion and the label applies one rule to all magnesium-containing products. A multivitamin with magnesium counts.
Timing that the label supports
Take eltrombopag at least 2 hours before or 4 hours after the magnesium product. The order matters: when the mineral product comes first, wait at least 4 hours before taking eltrombopag. The same label instruction applies to mineral supplements, antacids and calcium-rich foods. The inspected studies did not test shorter gaps with a magnesium product.
Evidence and practical considerations
Absorption & effectiveness
Magnesium-containing antacids chelate eltrombopag in the gut; a magnesium carbonate and aluminum hydroxide antacid reduced eltrombopag exposure by about 70% in healthy volunteers, and the label names magnesium among the cations to separate.
- Exact scope
- Magnesium supplements, antacids and laxatives in any salt; the tested product was a combination antacid. with Oral eltrombopag olamine tablets and oral suspension (PROMACTA and generics) and eltrombopag choline tablets (ALVAIZ). Both product labels give the same mineral-separation instruction; the products have different strengths and are not interchangeable dose for dose.
- Medication form and route
- oral medication; oral supplement
What remains uncertain
- Single-dose healthy-volunteer pharmacokinetics; magnesium was not tested alone or as a supplement salt; no platelet-count outcome data.
Factors that may matter: Magnesium dose and salt; Timing relative to the eltrombopag dose; Other cations in the same product; Calcium in the accompanying meal.
Read the supporting source summaries
Source 1: current product label
dailymed.nlm.nih.gov · Source check Sep 22, 2026
Population: People prescribed eltrombopag
The label states that eltrombopag chelates polyvalent cations such as magnesium in foods, mineral supplements and antacids, directs taking eltrombopag at least 2 hours before or 4 hours after any product containing them, and reports that a single 75 mg dose taken with an antacid containing 1,425 mg magnesium carbonate, 1,524 mg aluminum hydroxide and sodium alginate reduced AUC and peak concentration by approximately 70%.
How this applies: Exact eltrombopag (RxCUI 711942) in every marketed oral form; the label names iron, calcium, aluminum, magnesium, selenium and zinc by element and gives one spacing rule for all of them.
Magnesium was tested only as magnesium carbonate inside a combination antacid; magnesium oxide, citrate, glycinate and other supplement salts were not studied.
Source 2: current product label
dailymed.nlm.nih.gov · Source check Sep 22, 2026
Population: People prescribed eltrombopag
The ALVAIZ label repeats the PROMACTA rule word for word: eltrombopag chelates polyvalent cations such as iron, calcium, aluminum, magnesium, selenium and zinc, and ALVAIZ is taken at least 2 hours before or 4 hours after antacids, dairy products and mineral supplements to avoid significant reduction in absorption.
How this applies: Confirms that the cation rule is unchanged for the newer eltrombopag choline product; it adds no element-specific data.
No new interaction study is reported for the choline salt; the wording is carried over from the innovator label.
Source 3: pharmacokinetic crossover study
pubmed.ncbi.nlm.nih.gov · Source check Sep 22, 2026
Population: Healthy adult volunteers (18 men in study A; 26 adults in study B).
The high-calcium breakfast reduced eltrombopag AUC by 59% (geometric mean ratio 0.41; 90% CI 0.36 to 0.46) and peak concentration by 65%. Low-calcium meals did not change exposure whatever their fat content (AUC ratios 0.87 to 1.03). The aluminum and magnesium antacid reduced AUC and peak concentration by about 70% (AUC ratio 0.30; 90% CI 0.24 to 0.36).
How this applies: The tested antacid contained magnesium carbonate, so the 70% reduction is direct evidence for magnesium-containing antacids; it does not isolate magnesium from aluminum or alginate, and supplement salts were not tested.
Single doses in healthy volunteers read as an abstract; the antacid combined two cations plus sodium alginate, so the share of each is unknown; no mineral supplement product was tested.
Source 4: narrative review
pubmed.ncbi.nlm.nih.gov · Source check Sep 22, 2026
Population: Patients using antacids with susceptible medicines (review).
Polyvalent cations in antacids form insoluble chelate complexes that substantially reduce bioavailability of susceptible drugs such as tetracyclines and fluoroquinolones; magnesium ions may also speed gastric emptying; the review names eltrombopag among newer drugs susceptible to antacid interactions and describes dose spacing as the countermeasure.
How this applies: Supports the mechanism and the spacing approach; the quantitative eltrombopag result comes from the label and the original study.
Review read as an abstract; it summarises rather than reports the eltrombopag data.
Source 5: federal supplement fact sheet
ods.od.nih.gov · Source check Sep 22, 2026
Population: General consumer population; no eltrombopag co-use data
Magnesium supplements come as oxide, citrate, chloride, aspartate, lactate and other salts with differing absorption, and magnesium is also present in antacids and laxatives; listed medication interactions cover bisphosphonates, tetracyclines, quinolones, diuretics and proton pump inhibitors, with spacing of 2 hours before or 4 to 6 hours after magnesium for the antibiotics, but eltrombopag is not mentioned.
How this applies: Establishes the supplement forms and that magnesium-containing antacids and laxatives count as magnesium products; the interaction list omits eltrombopag.
Consumer and professional summary; it does not mention eltrombopag.
Research assessment: · Open full citations ↗
Timing & monitoring
The label directs taking eltrombopag at least 2 hours before or 4 hours after magnesium-containing antacids, laxatives and supplements.
- Exact scope
- Any oral product containing magnesium. with Oral eltrombopag olamine tablets and oral suspension (PROMACTA and generics) and eltrombopag choline tablets (ALVAIZ). Both product labels give the same mineral-separation instruction; the products have different strengths and are not interchangeable dose for dose.
- Medication form and route
- oral medication; oral supplement
- Timing or duration
- Every eltrombopag dose while the magnesium product is used
What remains uncertain
- The interval is a labelled instruction derived from the antacid and food studies; no study compared spacing intervals with a magnesium product.
Factors that may matter: Order of dosing (before versus after); Once-daily eltrombopag schedule.
Read the supporting source summaries
Source 1: current product label
dailymed.nlm.nih.gov · Source check Sep 22, 2026
Population: People prescribed eltrombopag
The label states that eltrombopag chelates polyvalent cations such as magnesium in foods, mineral supplements and antacids, directs taking eltrombopag at least 2 hours before or 4 hours after any product containing them, and reports that a single 75 mg dose taken with an antacid containing 1,425 mg magnesium carbonate, 1,524 mg aluminum hydroxide and sodium alginate reduced AUC and peak concentration by approximately 70%.
How this applies: Exact eltrombopag (RxCUI 711942) in every marketed oral form; the label names iron, calcium, aluminum, magnesium, selenium and zinc by element and gives one spacing rule for all of them.
Magnesium was tested only as magnesium carbonate inside a combination antacid; magnesium oxide, citrate, glycinate and other supplement salts were not studied.
Source 2: current product label
dailymed.nlm.nih.gov · Source check Sep 22, 2026
Population: People prescribed eltrombopag
The ALVAIZ label repeats the PROMACTA rule word for word: eltrombopag chelates polyvalent cations such as iron, calcium, aluminum, magnesium, selenium and zinc, and ALVAIZ is taken at least 2 hours before or 4 hours after antacids, dairy products and mineral supplements to avoid significant reduction in absorption.
How this applies: Confirms that the cation rule is unchanged for the newer eltrombopag choline product; it adds no element-specific data.
No new interaction study is reported for the choline salt; the wording is carried over from the innovator label.
Research assessment: · Open full citations ↗
Review and change history
- Publication status
- Published research summary
- Clinical review
- Not yet recorded
| Date | Update |
|---|---|
| Editorial update | |
| Editorial source audit clarified label scope, evidence limits and practical wording. No clinical approval was recorded. | |
| Research summary published | |
| Article prepared | |
| Prepared exact eltrombopag and Magnesium article from inspected current labeling and original sources, with uncertainty stated. |
Article revision: ed2434bfbcdf976a
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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