Content Supplied by NHS Choices

Antacid medicines

Everything you need to know about antacid medicines including their uses and side effects, with links to other useful resources.

Antacids are a type of medication that can control the acid levels in your stomach.

They are available over the counter from pharmacies and are commonly used to treat the symptoms of heartburn and indigestion.

How antacids work

Antacids work by counteracting (neutralising) the acid in your stomach that is used to aid digestion. This can reduce the symptoms of heartburn and relieve pain.

Some antacids also coat the surface of the oesophagus (gullet) with a protective barrier against stomach acid or produce a gel on the stomach’s surface which helps stop acid leaking into the oesophagus.

Different types of antacids

Antacids are available in the form of chewable tablets or liquid. They are sold under various brand names, but they contain common ingredients, including:

  • aluminium hydroxide
  • magnesium carbonate
  • magnesium trisilicate

Sometimes extra ingredients are added to help treat other problems, such as simeticone to relieve flatulence and alginates to prevent acid flowing into your oesophagus.

Who cannot take antacids?

Antacids are not suitable for everyone.

For example, many antacids are not recommended for children under the age of 12 and people with certain health conditions (such as kidney disease). Antacids can also interfere with other medications, so you may not be able to take them while you are being treated for another condition.

Antacids are generally considered safe to take during pregnancy, but you should discuss it with your GP or pharmacist beforehand.

Read more about who cannot take antacid medicines.

What are the possible side effects?

Like all medicines, antacids can have side effects. Common side effects include:

If you experience either constipation or diarrhoea after taking antacids, it may be possible to switch to an alternative medicine. Speak to your GP or pharmacist for advice.

Any side effects you experience while taking antacids should pass once you stop taking the medication. However, you should visit your GP if they continue.

Missed or extra doses

Take antacid medicines as directed on the patient information leaflet that comes with the medicine, or as advised by your GP or pharmacist.

If you miss a dose of an antacid, it will usually not be necessary to alter your next dose. It is likely that you can carry on taking your normal dose. For specific advice about what to do, refer to the patient information leaflet that comes with your medicine.

Taking extra doses could cause several unpleasant side effects, such as nausea, vomiting, diarrhoea and constipation.

Contact your GP or pharmacist immediately if you think that you have taken more antacids than you should have. Alternatively, you can call NHS Direct on 0845 46 47 or NHS 111 for advice.

Content Supplied by NHS Choices

Antacid medicines

Antacids are not always suitable for everyone, sometimes they need to be taken with caution or avoided completely.

Antacids are not suitable for everyone, sometimes they need to be taken with caution or avoided completely.

Use in children

Many antacid medicines are not recommended for children under the age of 12.

Antacids containing calcium are not recommended for long-term use in children because they can interfere with the rate that calcium is absorbed into the body and carried through the bloodstream. The right levels of calcium are vital for healthy bones and childhood development.

Prolonged use of antacids containing calcium can also lead to muscle weakness and cramps.

Furthermore, there have been a number of cases linking the prolonged use of antacids containing magnesium and aluminium with rickets, a developmental disorder in infants that causes softening and weakening of the bones.

Always read the patient information leaflet that comes with a medicine to ensure it is suitable for children. Check the correct dosage and seek the advice of your GP or pharmacist about giving antacids to children under 12 years old.

Use in pregnancy

Most types of antacids are considered to be safe to take during pregnancy.

However, if you are pregnant or breastfeeding, seek advice from your GP or pharmacist before taking antacids.

Use with other conditions

In some cases, you may be advised not to use some antacids if you have certain health conditions.

Speak to your GP or pharmacist if you have an existing health condition and are unsure whether antacids are suitable for you.

You can also check the patient information leaflet that comes with all medication to ensure the medicine is suitable for you.

Use with other medicines

Taking antacids can sometimes interfere with your body’s ability to absorb other medications you may be taking.

Therefore, you may be advised to stop taking other medication while you are taking antacids.

For example, you may not be able to take calcium supplements for a condition such as osteoporosis at the same time as some antacids. Antacids can also alter the effectiveness of some antibiotics.

However, it's important never to stop taking a medication prescribed for you without first consulting your GP or another suitably qualified healthcare professional.

Share this page