Skip to page content

What are antacids?

Antacids are medicines that are used to help relieve the symptoms caused by excess stomach acid, including mild acid reflux, heartburn, and indigestion.1,2 They are available in several formats, including solid or chewable tablets, powders and liquid antacids.2 Examples of antacids include sodium bicarbonate, calcium carbonate, and magnesium hydroxide.

How do antacids work?

While antacids contain a combination of various compounds, the active ingredient tends to be a salt of calcium, magnesium or aluminium.1 They relieve the symptoms arising from excess stomach acid by neutralising the acid.1,2 While your stomach naturally produces acid to help digest the food you consume, sometimes too much may be produced or the contents of the stomach, including acid, may flow back into the oesophagus (food pipe).3 These can lead to symptoms of acid reflux, which may be alleviated with antacids.3

Dietary choices & acid indigestion

Food choices and dietary habits often dictate risk of acid indigestion symptoms occurring.3-6 While most foods won’t necessarily increase the amount of acid your stomach produces, certain foods can cause the sphincter that keeps the contents of stomach from moving back up the oesophagus to relax or irritate the lining of your oesophagus, which can in turn lead to symptoms of acid indigestion.4,7 Some examples of such foods include spicy or fatty foods, citrus fruits, and even coffee.3,4 Dietary habits such as eating late night meals and drinking alcohol can also increase the risk of acid reflux.4,7

Choosing a suitable antacid: Understanding your options

When choosing an antacid, there are several factors to take into consideration. Antacids are a suitable option for managing symptoms of mild reflux (1 or 2 episodes per week).1,3 For symptoms that are more frequent or severe, you should consult a healthcare professional. Antacids are generally considered suitable to use while pregnant,3 however, you should always consult your healthcare provider before introducing any new medication, even over-the-counter ones, while pregnant. If you have certain medical conditions, antacids may not be a suitable option for you.1,2 Most antacids are high in sodium and may not be suitable if you are on a low-sodium diet.1,2 Please consult a healthcare professional if you are unsure or have any concerns.

Side effects of antacids

While antacids are generally well-tolerated, some side effects can occur. Even when used as directed, antacids may cause constipation or diarrhoea in some people.1,2 However, in most cases, side effects result from antacid misuse. Many antacids contain calcium and when they are taken in higher doses than recommended or for longer than directed, they can cause nausea, vomiting and other more serious complications.1,2 If you experience any unusual symptoms while using antacids, it's important to consult a healthcare professional.

How Gaviscon can help

Antacids are a useful tool to have in your kit when diet and lifestyle modifications are insufficient to relieve the symptoms of acid reflux and indigestion. Gaviscon offers a range of products designed to provide rapid relief from heartburn and indigestion, including Gaviscon Dual Action. Available in tablet, liquid and liquid sachet formats, Gaviscon Dual Action not only contains an antacid to neutralise stomach acid but an alginate as well, which forms a protective barrier on top of your stomach contents, to relieve the symptoms of heartburn and indigestion in two ways.

Understanding heartburn relief in pregnancy

During pregnancy, your body goes through a whirlwind of changes, including the potential for increased heartburn.3,4 While no medication is deemed universally 'safe' during pregnancy, antacids and alginates can be suitable options for managing occasional discomfort; however, diet and lifestyle changes should be trialled first.3,8 For pregnant women with persistent reflux symptoms despite diet and lifestyle changes, there is Gaviscon Extra Strength liquid. Designed to alleviate heartburn and indigestion, Gaviscon Extra Strength liquid is an alginate that is suitable for use during pregnancy.8 Always consult your healthcare provider before introducing any new medication, even over-the-counter ones, while pregnant.


This article is for general information only and not intended as a substitute for medical advice. All information presented on these web pages is not meant to diagnose or prescribe. In all health-related matters, always consult your healthcare professional.

Always read the label and follow the directions for use. RKT-M-33885.


  1. Salisbury BH and Terrell JM. Antacids. StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing;2023 Jan.
  2. Healthline. Antacids. Updated 25 April 2023. Available from: (accessed August 2023).
  3. Gastro-oesophageal reflux in adults [published August 2022]. In: Therapeutic Guidelines. Melbourne: Therapeutic Guidelines Limited; accessed August 2023.
  4. World Gastroenterology Organisation. WGO Handbook on Heartburn: A global perspective, 2015.
  5. MacFarlane B. Integr Pharm Res Pract. 2018;7:41–752.
  6. Talley NJ et al. Aust Prescr. 2017;40(6):209–213.
  7. Newberry C, Lynch K. J Thorac Dis 2019;11(Suppl 12):S1594–S1601.
  8. Strugala V, et al. ISRN Obstet Gynecol. 2012;2012:481870.