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What happens in the stomach?

Digestion actually begins even before you put food in your mouth. Once you smell or even think about food, you start to produce saliva. Once food enters your mouth the saliva begins to digest the food while teeth break food into smaller pieces, making it easier for us to swallow.2 Then food passes down the food pipe - the oesophagus. When a ring of muscle (sphincter) at the bottom of the oesophagus opens, the food goes down into our stomachs.2

Your stomach is basically like a bag that accepts and stores food entering from the oesophagus. In response to food entering the stomach, cells in the lining of the stomach produce stomach acid and enzymes to help break the food down further.2 In addition to the stomach acid, the muscles in the wall of your stomach help mix the food and the gastric acid juices together, helping to break down the food into a thick liquid.2 This liquid is then passed on to the small intestine, where the nutrients from the food you ate are absorbed into your bloodstream.2

What is stomach acid?

Stomach acid, also known as gastric juice, is made up of hydrochloric acid, digestive enzymes and other substances.3,4 Your body produces about 3 to 4 litres of stomach acid per day.4 Its function is to kill microorganisms, such as bacteria, that may have been swallowed to prevent it from reaching the intestine and causing infection.3 The stomach acid also plays an important role in absorbing nutrients such as calcium and iron.3,4 The hydrochloric acid breaks down food whilst the digestive enzymes split up protein in food.3

The acid in the stomach is highly acidic with a pH of below 4 and can destroy bacteria within 15 minutes.3 However, the stomach wall is protected against this acidity with a thick mucus coating to ensure it is not damaged by the hydrochloric acid.4

Can stomach acid cause any problems?

Although the role of stomach acid is very important, it may potentially cause problems. A common problem is gastroesophageal reflux, sometimes known as heartburn. Symptoms of heartburn are generally described as a burning sensation in the back of the throat and chest area, usually behind the breastbone.5,6 Another sign of heartburn is a bitter or sour taste in the back of the throat.6 This happens when the lower oesophageal sphincter (s-fink-ter) is weakened, which allows the acidic stomach contents to move back up into the oesophagus7 where they can cause pain or inflammation.8

What can you do if stomach acid reflux symptoms affect you?

There are a number of ways, such as lifestyle and dietary changes, to help improve symptoms associated with stomach acid reflux.9–12 However, if you are affected by stomach acid already, there are various medications that can help treat the symptoms of acid-related conditions, such as heartburn and indigestion symptoms. Gaviscon Dual Action Liquids and Tablets are an effective way to help relieve heartburn and indigestion.13

How does Gaviscon Dual Action relieve the pain and discomfort of heartburn and indigestion?

Gaviscon Dual Action works in two different ways to effectively relieve the symptoms of heartburn and indigestion:

  1. The antacid – the antacid in Gaviscon Dual Action neutralises excess stomach acid to relieve the pain and discomfort of indigestion.14
  2. The raft – the sodium alginate in Gaviscon Dual Action forms a thick layer (think of it like a ‘raft’) on top of your stomach contents. The ‘raft’ then acts as a physical barrier that helps keep your stomach contents where it belongs14 – in your stomach – and not in your oesophagus where it can cause discomfort and burning pain.5

Want fast-acting relief from heartburn and indigestion symptoms? Gaviscon Dual Action Liquid starts to soothe from 4 minutes!*15

So, as you can see, stomach acid is a vital part of the digestive process. Mostly it's our friend – but even if it becomes our foe, there are effective measures that can be taken to help.

*Strugala V, et al. J Int Med Res 2010. [RB sponsored]


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. RB-M-99690.


  1. Health Direct. Digestive system. Available at: (accessed July 2020).
  2. Gastroenterological Society of Australia. The Gastrointestinal (GI) System.
  3. Martinsen TC, et al. Int J Mol Sci2019;20(23):6031.
  4. Institute for Quality and Efficiency in Health Care (IQWiG). How does the stomach work? Available at: (accessed April 2022).
  5. Better Health Channel. Indigestion. Available at: (accessed July 2020).
  6. Department of Health (2019) Clinical Practice Guidelines: Pregnancy Care. Canberra: Australian Government Department of Health. Part I:56 Reflux (heartburn).
  7. Health Direct. What causes GORD. Available at: (accessed July 2020).
  8. Gastroenterological Society of Australia. Heartburn (factsheet).
  9. World Gastroenterology Organisation. WGO Handbook on HEARTBURN: A Global Perspective. 2015.
  10. Sandhu D and Fass R. Proc Shevchenko Sci Soc Med Sci 2018;52:10–15.
  11. Cho YK. J Neurogastroenterol Motil 2017;23:526–532.
  12. Therapeutic Guidelines March 2020 edition. Disorders of the oesophagus: Gastro-oesophageal reflux. Available at: (accessed July 2020).
  13. Gaviscon Dual Action Liquid Product Label.
  14. Mandel KG, et al. Aliment Pharmacol Ther 2000;14:669–690
  15. Strugala V, et al. J Int Med Res 2010;38:449–457.