Antacids Medication Definition

Antacids are products that neutralize gastric (stomach) acid to relieve dyspepsia (heartburn and indigestion). Antacids work by increasing the pH (acid level) of the gastric juices, which reduces the irritation to the stomach tissues. Most antacids contain mineral salts, which are alkaline.

Because of their high salt and mineral content, many antacids can cause constipation or diarrhea by drawing excessive fluid from the gastrointestinal tract. Sodium bicarbonate, which most people mix at home by dissolving baking soda in water, has such a high sodium level that it can affect blood pressure and the rhythm of the heart. Anyone who has cardiovascular disease (cvd), especially hypertension or arrhythmia, should not use sodium bicarbonate as an antacid.

Common Antacid Products

Common Antacid Products
Active IngredientRepresentative Products
aluminum hydroxideALternaGEL
aluminum/magnesium combinationMaalox, Mylanta
bismuth subsalicylatePepto-Bismol
calcium carbonateTums, Titralac
magnesium hydroxidemilk of magnesia
simethiconeGas-X, Phazyme
sodium bicarbonatebaking soda

Aluminum hydroxide, though very effective at neutralizing stomach acid, is so likely to cause constipation that it nearly always is combined with magnesium, which has the opposite effect. Doctors may recommend magnesium-based antacids, such as milk of magnesia, as laxatives to treat mild, occasional constipation. many antacid products also contain simethicone, a surfactant that breaks up intestinal gas bubbles to relieve bloating and flatulence.

Bismuth subsalicylate products such as Pepto-Bismol contain an aspirin-like ingredient that can cause the rare but serious side effect, reye’s syndrome, in children who have viral infections. Children should not take these products.

Antacids are available over the counter, without a doctor’s prescription. Occasional use of antacids can provide rapid relief of dyspepsia and other digestive discomforts. Antacids are most effective taken with food, which increases the time the antacid remains in the stomach, and liquid forms seem to be more effective than chewable forms.

Chronic or regular use of antacids can result in numerous health problems, ranging from “rebound” dyspepsia or gastric reflux (most common with calcium carbonate products) to osteoporosis (with magnesium products, as magnesium binds with calcium) and aluminum toxicity. Indications of antacid overuse include

  • Dyspepsia symptoms that seem to surge when the antacid dose nears the end of its effectiveness
  • The need to take higher or more frequent doses of the antacid to obtain relief
  • Mental confusion (indicating possible aluminum toxicity)
  • Chronic diarrhea (typically with aluminum/magnesium combination products)

Antacids also interfere with the actions of numerous medications. Other products, such as h2 antagonist (blocker) medications and proton pump inhibitor medications, are more effective for managing long-term gastric discomfort such as gastroesophageal reflux disorder (gerd). Antacids also interfere with H2 antagonist blockers. Children age 12 and under should not take antacids unless a doctor recommends them. A pharmacist can suggest an appropriate antacid for the circumstances and to avoid interfering with any medications a person is taking.


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