Antacids are medications that people can buy over the counter to help relieve heartburn and indigestion. They work by neutralizing stomach acid.

Heartburn is a burning pain that appears in the center of the chest and, sometimes, the throat. It is a common symptom of indigestion, which can also cause stomach pain and bloating.

In this article, we look at different types of antacids, how they work, and their side effects. We also discuss foods to avoid to minimize symptoms.

A close-up shot of antacids on a counter.Share on Pinterest
If symptoms of heartburn and indigestion occur occasionally rather than regularly, antacids may help manage symptoms.

People can buy antacids as tablets, liquids, or chewable gummies. Examples of over-the-counter (OTC) antacid brands include:

  • Alka-Seltzer
  • Gaviscon
  • Mylanta
  • Rolaids
  • TUMS

The active ingredients can vary according to the brand and specific product. However, common active ingredients include:

The Food and Drug Administration (FDA) recently withdrew all ranitidine (Zantac) products from the market due to a contaminant known as N-Nitrosodimethylamine (NDMA) that may cause cancer.

Antacids differ from other types of medications that doctors may prescribe for excess acid symptoms. These include proton pump inhibitors (PPIs) and histamine 2 (H2) blockers.

Heartburn is common during pregnancy, especially when the uterus is pushing on the stomach. This pressure can force stomach acid up the esophagus (food pipe), causing heartburn symptoms.

Pregnant women should use antacids cautiously during pregnancy. They should avoid antacids containing sodium bicarbonate, which could affect the fetus. However, TUMS and other products containing calcium carbonate are safe to take during pregnancy.

Women who are pregnant should not take antacids containing aspirin. Anyone who is unsure what antacids to take should speak to their doctor.

Acid reflux in children can have various causes, including, developmental delay and obesity. It is important that children with acid reflux symptoms see a doctor for a diagnosis.

OTC antacids that may be suitable for children include Alka-Seltzer, Maalox, and Rolaids. A pharmacist can offer more advice on appropriate options.

Antacids use a combination of calcium, magnesium, and aluminum salts as their active ingredients.

These medications work by neutralizing the acid in the stomach. They also inhibit pepsin, which is an enzyme that plays a role in protein digestion. Pepsin works with hydrochloric acid in the stomach to provide the acidic environment necessary to digest food.

Some antacids include a foaming agent called alginate that floats on top of the stomach contents and prevents acid from coming into contact with the esophagus.

Some people may experience side effects when taking antacids. These effects are usually associated with specific ingredients. Therefore, people may be able to reduce or eliminate side effects by switching to another brand.

Side effects associated with some antacids include:

  • diarrhea, with antacids that contain magnesium
  • constipation, with antacids that contain calcium or aluminum
  • inhibited bone mineralization, when taking a lot of antacids that contain aluminum
  • fluid retention or alkalosis, with antacids that contain sodium bicarbonate

The FDA issued a warning in 2016 about the risks associated with antacids that contain aspirin. There is a risk of serious bleeding with these products, particularly for people who are 60 years of age or older and those who have a history of stomach ulcers or bleeding problems.

People can use antacids to help relieve occasional heartburn or indigestion. If someone needs them every day, they should see their doctor, as they may have an underlying health condition, such as gastroesophageal reflux disease (GERD).

A person should always read the instructions before taking antacids, as different types of antacids contain different active ingredients.

As a 2020 review stated, people can take some antacids containing calcium carbonate when necessary to relieve symptoms. However, they should only take some antacids that contain aluminum hydroxide after meals and at bedtime.

Having overweight and eating late at night can make the symptoms of acid reflux worse. People may also find it helpful to avoid certain foods, including:

Learn more about foods to eat and avoid with GERD.

Antacids can affect the absorption of other medications. Sometimes, a person can resolve this by taking antacids at a different time to other medications. However, it is always best that they discuss this with a pharmacist or doctor.

Someone should talk to their doctor before taking antacids on a regular basis, particularly if they:

Additionally, antacids that contain aspirin can be a risk to people who take the following medications:

  • blood thinners, such as warfarin
  • steroids

Persistent symptoms of excess stomach acid could indicate a more serious condition that could worsen without treatment. The American College of Gastroenterology advise that a person see a doctor if they are using OTC antacids two or more times a week.

A doctor may diagnose someone with GERD. In this condition, a weak esophageal sphincter allows stomach acid to rise into the esophagus. Symptoms of GERD include:

Doctors often prescribe PPIs to treat GERD, which can sometimes lead to more serious conditions, including cancer. People should tell their doctor if anyone in their family has had esophageal cancer, gastric cancer, or Barrett’s esophagus, or if they have been living with acid reflux for a long time.

A person should see a doctor immediately if they are:

  • vomiting large amounts
  • experiencing regular projectile or forceful vomiting
  • vomiting fluid that is green or yellow, contains blood, or resembles coffee grounds
  • having problems breathing or swallowing
  • noticing pain in the mouth or throat when they eat

Heartburn occurs when acid in the stomach flows up into the esophagus and causes pain that moves from the stomach to the chest.

People can use OTC antacids for occasional symptoms of heartburn and indigestion. It is worth bearing in mind that active ingredients differ among brands, and side effects can vary, so it is important that people read the instructions before taking any antacids.

If someone needs antacids more regularly, this could indicate an undiagnosed health issue, and they should see their doctor.

Avoiding certain foods and maintaining a moderate weight can also help alleviate acid reflux symptoms. People who are taking other medications or have another health condition should be cautious about using OTC antacid medicines and check with their doctor or pharmacist first.

Pregnant women should use antacids with caution. Parents and caregivers should also take care to select suitable antacids for children. A doctor or pharmacist can help anyone who is unsure.


The antacids in this article are available to purchase in stores or online: