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April 15, 2014

Types of antacids and how they work

It’s not always easy figuring out which antacid will best help you find relief from heartburn. The following list describing each type of product should make the choice a little bit easier for you.


Antacids that contain alginate are very effective at easing acid reflux. Products that combine alginate with aluminum, calcium or magnesium (e.g. Gaviscon), create a foam barrier on top of the stomach contents and protect the esophagus from contact with gastric acid.

Stomach acid neutralizers

These antacids relieve both acid reflux and sour stomach by temporarily neutralizing the gastric acid already produced in the stomach. They are generally formulated with one or more of the following salts: calcium, aluminum or magnesium.
According to pharmacist Diane Lamarre, President of the Ordre des pharmaciens du Québec, antacids that contain only calcium carbonate (e.g. Tums) provide effective short-term relief. If, however, you take them several times a day or on a regular basis, they can cause what is known as “acid rebound,” a return of symptoms even more intense than prior to taking the medicine.

Antacids that contain both aluminum and magnesium (e.g. Diovol Plus) have the advantage of providing rapid relief of sour stomach and acid reflux by neutralizing gastric acid. Acid neutralizers generally work from 2 to 4 hours, depending on the person and the amount of gastric acid produced.  

Stomach acid blockers (H2 antagonists)

H2 antagonists, such as ranitidine (Zantac) and famotidine (Pepcid), provide longer-lasting relief, but not immediately. They act directly on the cells of the stomach to reduce the quantity of acid produced and are effective for both sour stomach and acid reflux.
H2 antagonists start to work after about one hour and provide relief that lasts 4 to 13 hours, in the case of ranitidine, and 10 to 12 hours in the case of famotidine. The recommended dose of ranitidine is 75 to 150 mg (once or twice day) and for famotidine, 10 mg (once or twice a day).

Ingredients to avoid

Products containing a salicylate, such as bismuth subsalicylate, (e.g. Pepto-Bismol or Stomak-Care) or acetylsalicylic acid (e.g. Alka-Seltzer) provide limited effectiveness.

They can also interact with other medications, including certain anticoagulants, antibiotics or diabetes medicine. In addition, they should never be administered to children under the age of 18, given their increased risk of developing Reye’s Syndrome, a serious disease of the brain and liver.

Follow the dosing instructions

Some antacids may look and even taste like candy, but, as Diane Lamarre points out, they must be treated as medicine. It is important to always follow the dosing instructions and pay special attention to the concentration of the product you are using. Remember that there are regular formulas (15 to 30 ml in liquid form or 1 to 4 tablets) and concentrated formulas (10 ml in liquid form or 1 to 2 tablets).

When taking an antacid, timing is everything. For digestion to occur, the body needs to produce gastric acid. This is why you should wait at least one hour after eating before taking it. “Bedtime is another perfect time to take an antacid, since it will have the chance to provide substantive relief,” explains Diane Lamarre.

To learn more:

Brûlures d’estomac, antiacides, Protégez-Vous, December 2012 (In French only)
10 conseils pour bien digérer vos Fêtes, Protégez-Vous, December 2011 (In French only)


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