Over-the-Counter Drugs - Antacids

Over The Counter Drugs Antacids 2737
Photo by: Diego Cervo

The stomach is a very busy organ. It stores food, mixes food with gastric secretions, and empties food into the small intestine for digestion and absorption. Gastric acid helps with digestion and absorption of food, and it also kills bacteria found in the stomach. Acidity is measured using a pH value. The pH of gastric acid is extremely high, approximately 3 million times more acidic than the pH of blood. The stomach has a lining to protect it from this acid. The lining secretes mucus and bicarbonate, which form a barrier against the acid.

There are substances that interfere with this lining and cause the stomach to become irritated by the acid. These substances include medications, alcohol, and caffeine. Smoking and certain diseases affect the lining as well. When acid irritates the stomach, the result is heartburn, gas, indigestion, and sometimes ulcers. There are two main types of antacids to treat these problems: H2-antagonists and non-H2-antagonists. (H2 is a type of acid. The antacid types are called such because some people have an overproduction of acid.)


Many former prescription medicines can now be bought over the counter, such as Advil (pain reliever), Aleve (pain reliever), Monistat (treats yeast infections), and Tagamet HB (antacid). The FDA switches a prescription to OTC status if it determines that people can safely and effectively use the medicine after reading the medicine's package label and without physician instruction. The FDA also looks at how the medicine interacts with other drugs, how safe it is in high doses, and the risk of abusing this medicine before it approves a medication's OTC status. OTC drugs that used to be prescription medicines are usually sold in lower doses than could be prescribed by a physician.

NON-H2-ANTAGONISTS. Non-H2-antagonists were the first antacids to be available without a prescription. They work by neutralizing the gastric acid in the stomach. This makes it easier for the lining to protect the stomach. These antacids contain calcium carbonate, sodium bicarbonate, aluminum salts, or magnesium salts as their main ingredients.

Calcium carbonate takes longer to dissolve than the other ingredients but is more effective in neutralizing the acid. Calcium carbonate antacids are intended for short-term use only. Some people believe that the calcium in antacids can be used as a dietary supplement, but the amount of calcium that is absorbed by the body is actually very small.

Antacids that use sodium bicarbonate offer almost instant relief, but should not be taken by people who are on a low-sodium diet, have congestive heart failure, high blood pressure, cirrhosis, swelling, or kidney failure because of the sodium (salt) that the body absorbs from these antacids.

Aluminum salts dissolve very slowly and take longer to work. These antacids can cause constipation. They are often combined with magnesium salts, which cause diarrhea. Magnesium salts neutralize acid better than aluminum salts, but not as well as calcium carbonate or sodium bicarbonate, and they don't provide long-term relief. People with kidney failure should not use aluminum salt or magnesium salt antacids.

Some antacids have other ingredients such as aspirin or a chemical called simethicone, which relieves gas. Sometimes sodium bicarbonate antacids also contain alginic acid. This acid reacts to the sodium bicarbonate and makes a foam that treats heartburn.

H2-ANTAGONISTS. H2-antagonist antacids are now available without prescription. Originally designed to treat ulcers, they also work well for heart-burn, acid relief, and sour stomachs. These antacids work by blocking the formation of excess acid in the stomach. They do not neutralize the acid that is already there. These antacids should not be taken for more than two weeks.

Antacids in liquid form absorb faster than the other varieties, so they provide faster relief. Chewable tablets should be chewed thoroughly and work best if taken with water. Some interactions with other drugs may occur because the other drugs can bind to the antacids and will not get fully absorbed. Pregnant women should not use antacids unless recommended by their doctor.

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