What effect does aluminum-containing antacids have on bowel movements?

Aluminum-containing antacids primarily cause constipation due to the nature of aluminum's interaction with the digestive system. Aluminum ions can bind to phosphate in the intestine, leading to reduced gastrointestinal motility. This can result in a decrease in the frequency of bowel movements and a potential buildup of stool in the intestines.

In contrast, other antacids containing magnesium can lead to diarrhea because magnesium stimulates bowel activity. However, aluminum's specific pharmacological properties contribute to its constipating effect. Thus, when considering aluminum-containing antacids, it's important to recognize that their mechanism tends to slow down bowel transit time, ultimately leading to constipation in individuals taking these medications.