Antacids have long been used to treat ulcers and serious stomach upset due caused by stomach acid, as well as to relieve heartburn, but they can interfere with the body’s absorption of other drugs.

They should be used no earlier than two hours prior to or four hours after taking interacting medications.

As opposed to other drugs that control problems from an acidic stomach such as cimetidine (TAGAMET) or omeprazole (PRILOSEC) that reduce production of acid by the stomach, antacids directly neutralize acid.

Antacids generally interact with other drugs in one of two ways: by binding to the molecules that make up those drugs or by interfering with drug absorption by reducing the acidity of the stomach.