Objective: To investigate the laxative effect of reducing the number of daily doses of magnesium oxide (MgO), while maintaining the total daily dose of MgO in patients with good bowel movements.Patients and Methods: The retrospective analysis involved 11 patients with regular bowel movements who were prescribed MgO for constipation upon admission to a nursing care facility accompanied by home visits by a pharmacist. This investigation was conducted before and after reducing the number of daily doses from three to two, or from two to one, over a two-week period.Results: The number of bowel movements was 7.6 ± 3.4 and 6.6 ± 4.0 times for two weeks before and after the change in dosage frequency, respectively. The difference was not statistically significant (P=0.09). The Bristol Stool Form Scale was 3.9 ± 0.9 and 4.0 ± 0.9 two weeks before and after the change, respectively, which was not significant (P=0.93). Two weeks after the change, the MgO regimen remained unchanged and no on-demand laxatives were administered.Conclusions: The results suggest that reducing the number of daily doses of MgO does not affect its laxative action.