Supplement
Magnesium Oxide
Half-life
~42 days
What is Magnesium Oxide?
High elemental magnesium content (60%) but poor bioavailability (~4%). Primarily used as a laxative.
How Magnesium Oxide works
Poorly absorbed — most remains in the GI tract where it draws water osmotically, producing a laxative effect. The small fraction absorbed functions as other magnesium salts.
Benefits & uses
Common uses: Constipation relief, heartburn, cheap magnesium supplementation (though poorly absorbed).
Magnesium Oxide dosage
- Typical dose
- Not recommended for magnesium repletion — use glycinate or malate instead. If used: 250–400 mg with food.
Magnesium Oxide half-life
~42 days (tissue magnesium, but low absorption limits tissue repletion)
Magnesium Oxide side effects
Significant osmotic laxative effect. Poor absorption means less systemic benefit.
- Diarrhea and loose stools (osmotic laxative)
- Poor choice for correcting magnesium deficiency due to ~4% bioavailability
- GI cramps at high doses
Track Magnesium Oxide in Protokol.
Log doses, model half-lives, check interactions, and line it all up against your bloodwork. Free on iPhone and Android.
