Magnesium oxide effect on gastric pH (intragastric acidity)
Published human data specifically quantifying how long magnesium oxide (MgO) takes to raise intragastric pH are limited. (medlineplus.gov)
Expected time course for acid neutralization
For solid oral calcium/magnesium antacid formulations, acid-neutralizing effects begin within the first minutes after contact with gastric fluid in an artificial stomach model. [1]
What determines the real-world timing
The time to change gastric pH depends on formulation and dissolution because the neutralization requires sufficient surface contact with gastric acid. [1]
Practical clinical interpretation
If magnesium oxide is taken as an antacid-type dose for dyspepsia/heartburn, gastric pH changes are expected to occur on a minutes timescale rather than hours based on available antacid pharmacodynamics in stomach-mimicking models. [1]