Depending upon the brand name, some of the active ingredients found in antacids include magnesium carbonate, aluminum hydroxide, calcium carbonate and sodium bicarbonate. These substances are bases, and can help to neutralize the stomach acidity that causes discomfort by increasing the pH level. Over-the-counter brand-name medications, such as Maalox, Tums, Rolaids, Brioschi, Pepto-Bismol, Alka-Seltzer and Mylanta, are all antacids.
The stomach discomfort that the antacid products are intended to relieve is caused by hydrochloric acid (HCl). A normal part of the digestive process, hydrochloric acid is a gastric juice secreted by the lining of the stomach and is required by the enzyme pepsin for the catalytic breakdown of proteins in food. When hydrochloric acid comes in contact with exposed nerves in the gastrointestinal mucosa, they send a pain signal to the central nervous system. In addition to neutralizing hydrochloric acid, antacids may also facilitate mucosal healing.
The action of antacids can possibly cause problems because of the reduced stomach acidity they produce. Stomach acidity helps to kill ingested bacteria, and reduced acidity levels may increase susceptibility to infection. There may also be an impaired ability to break down proteins and absorb nutrients, such as the B vitamins and iron. Overall, side effects produced by antacids will vary depending upon interactions with other medicines and the individual taking them.