Antacids Side Effects – The Truth About Antacids and Heartburn

In our ongoing series into the effectiveness and possible dangerous side effects of heartburn remedies, today we will turn our attention to one of the oldest acid reflux remedies of all: antacids.

Antacids – What Are They and How Do They Work?

At least in the United States, by far the most popular antacid is a compound known as calcium carbonate. This is the main ingredient in the majority of over-the-counter (such as TUMS).

Calcium carbonate works by directly reacting with stomach acid. Every molecule of calcium carbonate reacts with 2 molecules of hydrochloric acid (stomach acid) and forms a calcium salt (similar to table salt), water, and carbon dioxide:

CaCO3 + 2 HCL → CaCl2 + CO2 + H2O

As a result, from a chemical perspective, antacids like calcium carbonate relieve heartburn by neutralizing stomach acid and they do this very well. “Extra strength” varieties simply offer extra calcium carbonate to neutralize more stomach acid.

Another common antacid is baking soda, also known as sodium bicarbonate, operates via similar reactions. Baking soda for heartburn relief has become less popular over the years after some serious side effects began to emerge.

The Truth About Antacids and Heartburn

On paper, the idea that antacids can reduce heartburn and make us feel better looks great. However, this does not always work out so well in practice. There is a simple question that many people do not stop to ask:

What other effects does consuming calcium carbonate have on my body? What antacids side effects exist?

There are two areas we need to look at: the side effects of neutralizing stomach acid and the side effects of consuming the excess calcium molecules left behind by the reaction of calcium carbonate and stomach acid.

Problems with Neutralizing Stomach Acid

One thing we cannot forget when working with digestive issues like heartburn is that the stomach is acidic for a reason: it helps us digest our food. An acidic pH serves two primary functions:

An acidic pH denatures proteins, forcing them to unfold so that digestive enzymes can break them up into smaller pieces.

An acidic pH activates pepsin, a crucial digestive enzyme which then starts breaking up denatured proteins. Pepsin stops working when pH rises, as it does temporarily with the use of an antacid.

When we digest foods, our body just does not mush up food into a liquid but rather breaks it down into very microscopic pieces. Our body prefers to absorb single amino acids rather than whole proteins; amino acids are so small that we cannot possibly hope to see them with our eyes or even under a standard light microscope!

Without stomach acid and pepsin, we cannot digest proteins properly. For this reason, people who use antacids often report constipation, indigestion, and related digestive problems.

However, these are relatively mild and may not happen in everyone.

Side Effects of Antacids – Problems with Excess Calcium Consumption

While digestive side effects are more likely, the chronic use of calcium carbonate can lead to two much more serious health problems.

The first problem is that of kidney stones; frequent usage of calcium carbonate can indeed to kidney stone formation (1). This is particularly true if you have a family history of kidney stones. Kidney stones are extremely painful but generally are not life-threatening.

The real danger with calcium carbonate is that it can lead to hypercalcemia (i.e. high blood levels of calcium), which may cascade into kidney damage and ultimately metabolic alkalosis (blood pH higher than normal values), which is a life-threatening condition (2).

Are Antacids Dangerous?

The more serious side effects of antacids are extremely rare and are more typical of antacid abuse. We do not recommend using antacids on a daily basis (or several times per day) as this may lead to undesirable side effects. Like many over the counter medications, they are fine occasionally but excessive usage may be dangerous.

It is recommended that you speak to your doctor about your acid reflux if you experience heartburn two times a week or more rather than trying to rely on antacid usage.


1. Allie S., & Rodgers A. Effects of calcium carbonate, magnesium oxide and sodium citrate bicarbonate health supplements on the urinary risk factors for kidney stone formation. Clin Chem Lab Med. 2003 Jan;41(1):39-45.

2. Jeong JH, & Bae EH. Hypercalcemia associated with acute kidney injury and metabolic alkalosis. Electrolyte Blood Press. 2010 Dec;8(2):92-4.

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  1. Baking Soda For Heartburn – Sodium Bicarbonate as a Reflux Remedy?
  2. Mustard for Heartburn Relief? The Truth Revealed
  3. Milk and Heartburn – Is Milk A Good Acid Reflux Remedy?
  4. The Long-Term Effects of Heartburn or Acid Reflux
  5. Dietary Fat and Acid Reflux – The Truth Revealed