Which of the following antacids is known to cause diarrhea?

Magnesium hydroxide is known to cause diarrhea due to its osmotic properties. When magnesium hydroxide is ingested, it can draw water into the intestines, leading to a laxative effect. This is particularly relevant when large doses are consumed or when the component is used as a standalone treatment rather than in combination with other compounds that might mitigate this side effect.

In contrast, calcium carbonate is primarily associated with constipation, while aluminum hydroxide can also contribute to constipation when used as an antacid because it can bind to phosphate, potentially leading to reduced gut motility. Iron supplements, while they can cause gastrointestinal distress, more commonly lead to constipation rather than diarrhea. Therefore, identifying magnesium hydroxide as the source of potential diarrhea in this context is essential for understanding the side effects associated with different antacids.