Antacids are the oldest effective medications for heartburn. Chalk (calcium carbonate) has been chewed for centuries to provide some relief and is still popular.
Most commercially available antacids are combinations of aluminum and magnesium hydroxide. Some effervescent antacids contain sodium bicarbonate, that old household remedy for tummy aches known as “baking soda.”
Some antacids are combined with an alginate [an insoluble substance that increases surface tension in liquid] to form a compound that floats on gastric fluids to protect the esophagus from acid exposure.
Antacid tablets are slow acting and have less neutralizing power than a liquid form of antacid. Tablets must be chewed, and may not interact well with gastric acid. For most, the convenience of tablets far outweighs these slight disadvantages.
Such a variety of commercial antacids occupy pharmacists’ shelves that this discussion will concentrate on their basic ingredients (See accompanying Table). Note that only a few commercial preparations are cited as examples.