Antacids are commonly used during pregnancy, and they are approved for the relief of symptoms of gastroesophageal reflux disease (GERD) during pregnancy. However, there are no reports of the quantification of the absorption of aluminum and magnesium in the antacid magaldrate in women. The aim of this study was to quantify the rate and magnitude of absorption of aluminum and magnesium in magaldrate. An open-label, controlled, randomized, one-treatment study with a two-group design was conducted in healthy women in a fed state. The volunteers had a standard breakfast, and 30min later, they were given a single-medication sachet containing 500mg of sodium alginate, 267mg of sodium bicarbonate, 800mg of magaldrate, and 120mg of simethicone (groupA, n = 8) or no medication (groupB, n = 2). Blood samples were obtained 36h before and up to 12h after antacid administration. The method used for quantification was inductively coupled plasma-mass spectrometry. There was no absorption of aluminum in any of the blood samples from the healthy volunteers who received the drug or in those from the control group. Magnesium was detected at normal concentrations. These findings suggest that the use of this antacid is safe and without risk in healthy women, including pregnant women. Clinicaltrials.gov registration: NCT06367452.