Tom Cramer is a staff writer for FDA Consumer. Drug manufacturers must make and label their antacids according to specific guidelines in FDA's monograph on antacids. Specifically, each active ingredient included in the antacid product must contribute at least 25 percent to the product's total neutralizing capacity. In a laboratory test, the antacid must neutralize a specific amount of acid and keep it neutralized for at least 10 minutes. The label can't make any other medical claims.
Antacids can increase or decrease the speed at which some medications are eliminated from the body.
For example, antacids can block the body's absorption of tetracycline, an antibiotic. The opposite of an acid is a base, and that's exactly what antacids are. But a base all by itself can't neutralize the acid inside you. As its name suggests, it's heavy in sodium. Antacids in the form of calcium carbonate or calcium phosphate are potent and fast-acting.