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Magnesium Citrate

Mineraloral · inferred

Highly bioavailable organic magnesium salt. Absorbs significantly better than magnesium oxide due to superior solubility in gastric acid. Often used for its mild osmotic laxative effect in addition to supplementation. Good general-purpose form for correcting deficiency.

Projected serum levels — 300 mg, once daily

Magnesium Citrate
Magnesium Citrate modeled serum levels, 300 mg once daily over 121 days Population-based pharmacokinetic estimate. Steady state reached after approximately 91 days. 0 1.3k 2.5k 3.8k 5k Day 0 Day 30 Day 61 Day 91 Day 121 Time on a regular schedule ≈ steady state · day 91
Magnesium Citrate modeled serum levels with a loading dose of 900 mg, then 300 mg once daily The first dose is larger so levels approach steady state faster. 0 1.3k 2.5k 3.8k 5k Day 0 Day 30 Day 61 Day 91 Day 121 Time on a regular schedule

Maintenance schedule: 300 mg once daily (oral).

Loading schedule: 900 mg on day 1, then 300 mg once daily — reaching therapeutic levels sooner.

Modeled steady state after ~91 days: peak ≈ 4.7k mg, trough ≈ 4.7k mg body load. Population-based estimate over 121 days for a 300 mg dose at a 70 kg reference body mass — the interactive app scales curves to your doses, timing, and body mass.

Key facts

Category
Mineral
Route modeled
Oral
Model confidence
inferred
Half-life
42 days
Common dose
300 mg
Suggested maximum
600 mg/day
Reference dose range
150–600 mg (single dose)
Suggested cadence
once daily

Documented interactions

  • caution
    Alendronate (Fosamax) + Magnesium Citrate Chelation

    Alendronate (Fosamax) (bisphosphonate) forms insoluble complexes with Magnesium Citrate in the GI tract, reducing absorption of both.

  • caution
    Armour Thyroid (Desiccated Thyroid Extract) + Magnesium Citrate Chelation

    Armour Thyroid (Desiccated Thyroid Extract) (thyroid hormone) forms insoluble complexes with Magnesium Citrate in the GI tract, reducing absorption of both.

  • caution
    Caffeine + Magnesium Citrate Depletion

    Caffeine increases urinary magnesium excretion.

  • caution
    Calcium (Citrate) + Magnesium Citrate Absorption

    Calcium and magnesium compete for the same absorption pathways. High-dose calcium reduces magnesium uptake.

  • caution
    Ciprofloxacin (Cipro) + Magnesium Citrate Chelation

    Ciprofloxacin (Cipro) (fluoroquinolone antibiotic) forms insoluble complexes with Magnesium Citrate in the GI tract, reducing absorption of both.

  • caution
    Doxycycline + Magnesium Citrate Chelation

    Doxycycline (tetracycline antibiotic) forms insoluble complexes with Magnesium Citrate in the GI tract, reducing absorption of both.

Serum checks 12 modeled interaction pairings for magnesium citrate across your whole stack — absorption conflicts, enzyme inhibition, and nutrient depletion included.

Research behind this entry

  1. Higher Bioavailability of Magnesium Citrate as Compared to Magnesium Oxide Shown by Evaluation of Urinary Excretion and Serum Levels After Single-Dose Administration Kappeler D et al. · BMC Nutrition, 2017 DOI

    Randomized crossover study in 20 healthy men showing magnesium citrate produced significantly higher serum magnesium and urinary excretion than magnesium oxide after single dose.

  2. Magnesium Bioavailability from Magnesium Citrate and Magnesium Oxide Lindberg JS et al. · Journal of the American College of Nutrition, 1990 DOI

    Found urinary magnesium excretion significantly higher after magnesium citrate vs oxide loading, establishing citrate as the more bioavailable form.

  3. Mg Citrate Found More Bioavailable Than Other Mg Preparations in a Randomised, Double-Blind Study Walker AF et al. · Magnesium Research, 2003 DOI

    60-day RCT comparing citrate, chelate, and oxide forms at 300 mg/day showed organic forms (citrate, chelate) had greater absorption than oxide.

3 published studies referenced in the app, each with a plain-language summary.