What is a common adverse effect of antacids containing calcium?

Antacids that contain calcium can lead to constipation due to the nature of calcium's effects in the gastrointestinal system. Calcium has a tendency to increase muscular contractions in the intestines, which can slow down the passage of stool, leading to harder stools and reduced bowel movement frequency. This is particularly noteworthy for individuals who may already have slower bowel transit times or who are predisposed to constipation.

In contrast, other digestive issues like flatulence, diarrhea, and headaches can occur with various medications or dietary factors, but they are not directly associated with calcium antacids. For instance, while certain antacids may cause flatulence due to gas produced from their ingredients, calcium-based formulations are less commonly linked to this effect compared to those containing magnesium or sodium. Similarly, antacids are generally not known for causing diarrhea; in fact, medications high in magnesium are more often linked to this issue. Headaches can be multifactorial and are usually not a direct side effect associated specifically with calcium-containing antacids.