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Indigestion medicine

Many people use indigestion medicines, usually just occasionally but sometimes more regularly. The same medicines can be used to treat more serious medical conditions such as stomach ulcers or acid reflux. If you need to use indigestion medicines regularly it's very important to see a doctor to get it checked out in case it is caused by an underlying condition that needs further investigations and treatment.

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What is indigestion?

Dyspepsia (indigestion) is used to describe pain and sometimes other symptoms which come from your upper gut (the stomach, oesophagus or duodenum). The symptoms of indigestion often occur soon after eating.

Most people have indigestion from time to time but it doesn't last long and doesn't cause any problems. Some people can have frequent or severe bouts of indigestion and if that is the case, it's very important to see a doctor to get it checked out and receive the right treatment. See also the separate leaflet called Indigestion (Dyspepsia).

When acid from the stomach leaks up into the gullet (oesophagus), the condition is known as acid reflux. This may cause heartburn and other symptoms. See also the separate leaflet called Acid Reflux and Oesophagitis.

What are indigestion medicines?

Indigestion medicines can be used to relieve the symptoms of indigestion such as discomfort in your upper tummy (abdomen) or chest. There are three main types of medicine for indigestion: (see the links for more information about each type of indigestion medicine). These are:


Antacids usually contain either aluminium or magnesium compounds. They work by reducing the acidity in your stomach. They are often combined with other substances such as alginates, which form a protective layer that floats on the surface of your stomach contents. This helps prevent acid going back up into your gullet (oesophagus) - the tube that connects your mouth to your stomach - and so protects against acid reflux and oesophagitis.

H2 blockers

These medicines work by reducing the amount of acid made in your stomach. By reducing the acidity in your stomach they can be used to treat indigestion, acid reflux, stomach (gastric) ulcers and duodenal ulcers.

The most commonly used H2 blocker in the UK was ranitidine but it has been discontinued as a precaution because of some impurities found in the medicine. If your doctor feels that you need an H2 blocker, they may prescribe a different one.

Proton pump inhibitors (PPIs)

These medicines also reduce the amount of acid made in your stomach. They are also used to treat indigestion and acid reflux, and stomach and duodenal ulcers. Proton pump inhibitors are very effective at reducing stomach acid and are particularly effective at treating acid reflux and gastro-oesophageal reflux disease (GORD).

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How do indigestion medicines work?

The exact mechanism of action varies between the different types of medication. Proton pump inhibitors stop an enzyme from working so that stomach cells can't pump acid into the stomach. H2 blockers bind to receptors in the stomach cells which interferes with the production of stomach acid. Antacids neutralise the acid in your stomach by stopping the action of an enzyme which creates acid.

What side-effects can indigestion medicines cause?

Indigestion medicines are usually effective and don't cause any side-effects. The following describes some of the more common side-effects but always read the information provided with the medicine. If you have any doubts or concerns then get advice from your pharmacist, nurse or doctor.


Antacids that contain magnesium tend to act as a laxative and may cause diarrhoea. Antacids that contain aluminium have the opposite effect and may cause constipation.

Many antacids contain both aluminium and magnesium compounds so that there is a neutral effect on your bowels. Antacids that contain magnesium carbonate may release carbon dioxide gas in your gut (bowel) and this can cause belching.

H2 blockers

The most common side-effects of H2 blockers can include:

Proton pump inhibitors

The most common side-effects of proton pump inhibitors include:

  • Stomach upset - for example, feeling sick (nausea), stomach ache, or wind (flatulence); tummy pain, and being sick (vomiting).

  • Diarrhoea.

  • Constipation.

  • Headache.

If you take a proton pump inhibitor for a long time, you are likely to get rebound symptoms of acid reflux when you stop, because your stomach has got used to making more acid as a response to the medicines. This usually only lasts for a few days, up to a few weeks as a maximum and it can be treated with antacids or H2 blockers.

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How to help indigestion without medicine

Apart from taking an indigestion medicine, there are many things you can do to help, such as:

If you have heartburn reflux, it may help if you:

  • Try to eat smaller meals more frequently rather than larger meals.

  • Avoid eating for the few hours before you go to bed.

  • Raise the head of your bed.

When should you see a doctor?

You should see a doctor if you continue to have indigestion symptoms despite a few weeks of using an indigestion medicine. You should always see a doctor if you have any of the following:

  • Difficulty swallowing (feeling food getting stuck or feeling a lump in your throat).

  • Losing weight without dieting.

  • Having a lot of pain in your stomach (abdomen).

  • Being sick (vomiting), especially if there is any blood in the vomit.

  • If you’re over 55 and get frequent bouts of indigestion.

  • Noticing blood in your poo (stools) when you go to the toilet.


Indigestion and acid reflux are common in pregnancy. It usually helps to reduce the symptoms if you:

  • Eat smaller meals more often.

  • Avoid foods and drinks that might make your indigestion worse.

  • Try not to eat within a few hours of going to bed.

For more information, see the separate leaflet called Indigestion and Acid Reflux in Pregnancy (Dyspepsia).

Further reading and references

Article history

The information on this page is written and peer reviewed by qualified clinicians.

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