Your stomach is the only organ of your digestive system that possesses the adaptations necessary to withstand prolonged exposure to gastric acid. A muscular ring at the junction of your stomach and esophagus normally prevents gastric acid from entering your esophagus. If this mechanism fails, stomach acid may escape into your esophagus and irritate the lining tissues. You experience this esophageal irritation as heartburn. Antacids relieve heartburn by chemically neutralizing gastric acid, a short-term solution to halt the irritation of your esophagus.
Gastric Acid
In chemical parlance, gastric acid is concentrated hydrochloric acid, or HCl. Hydrochloric acid is a powerful chemical as evidenced by its numerous industrial uses, including refining ores and cleaning metals. Within your stomach, hydrochloric acid liquefies meat and other solid foods by breaking down the chemical bonds that hold food together. Your stomach normally remains unharmed by the hydrochloric acid, thanks to a thick layer of mucus that coats the lining. Your esophagus does not have the same protective mucus found in your stomach. Thus, your esophageal lining is easily irritated by exposure to gastric acid. The irritated tissues stimulate sensory nerves and you experience heartburn pain.
Neutralization
The many antacids available at your local pharmacy contain different active ingredients that share a common property: they are all capable of neutralizing stomach acid. You may recall from your high school chemistry class that alkaline chemicals, also known as bases, neutralize acids. The chemical reaction between the hydrochloric acid in your stomach and the base in an antacid reduces the acidity of your stomach contents. The neutralization of your stomach contents typically alleviates the irritation of the esophageal lining, thereby relieving your heartburn.
Antacid Ingredients
The neutralizing chemicals in antacids are sodium, potassium, magnesium, calcium or aluminum salts. A partial list of the active ingredients found in over-the-counter antacids includes sodium bicarbonate, potassium bicarbonate, aluminum carbonate, aluminum hydroxide, magnesium hydroxide, magnesium carbonate, magnesium oxide, magnesium trisilicate and calcium carbonate. Many antacids brands contain a combination of these acid-neutralizing chemicals.
Drug Interactions
By altering the chemistry in your stomach, antacids may affect the absorption of certain medications. For example, antacids that contain magnesium or aluminum may decrease absorption of the heart medication digoxin. Similarly, the absorption of the antibiotic tetracycline is usually reduced if taken with an antacid. Absorption of the decongestant pseudoephedrine and the antianxiety medication diazepam may increase when taken with an antacid. Because antacids interact with many medications, talk with your doctor about possible interactions between antacids and any medicines you take regularly.
Side Effects
Although antacids are over-the-counter medicines, there are potential side effects, which may be serious if you have certain preexisting medical conditions. Sodium-containing antacids, for example, may contribute to dangerous fluid overload if you have heart failure, kidney failure or cirrhosis of the liver. Less serious side effects include diarrhea from frequent use of magnesium-containing antacids and constipation associated with calcium- and aluminum-based antacids. Read and follow the precautions on the product label and contact your doctor if you have questions or concerns, especially if you have a chronic illness.
Warning
Antacids are usually effective at relieving heartburn. However, they do not correct the underlying cause of your symptoms or reverse tissue damage. If you have persistent, recurrent or worsening heartburn, see your doctor to determine the cause and appropriate treatment. Contact your doctor right away if you pass black, tarry stools or vomit stomach contents that resemble coffee grounds. Call 911 if you vomit bright red blood.
References
- "Human Biology"; Daniel D. Chiras, Ph.D.; 2010
- United States Environmental Protection Agency; Hydrochloric Acid (Hydrogen Chloride); January 2000
- "Mucosal Immunology"; Jiri Mestecky, M.D., Ph.D. et al; 2005
- "The Basics of Chemistry"; Richard L. Myers, Ph.D.; 2003
- Drugs.com; Antacids; American Society of Health-System Pharmacists; February 2011
- FamilyDoctor.org; Digoxin: A Medicine for Heart Problems; November 2010
- Drugs.com: Tetracycline
