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Dr Roger Henderson
Reviewed by Roger HendersonReviewed on 29.04.2024 | 3 minutes read

Antacids are a type of medication used to relieve indigestion in adults and children, and are best known as brands such as Gaviscon, Rennie, and Maalox. They usually come in chewable tablets or as a liquid, and are available to buy without a prescription. Some antacid products contain other active ingredients, such as sodium alginate (a raft-forming agent that relieves heartburn).

Examples of antacids include calcium carbonate, sodium bicarbonate, aluminium hydroxide, magnesium carbonate, and potassium bicarbonate.

Doctor’s advice

How do they work?

Indigestion is often caused by your stomach producing too much acid, which can irritate the lining of your stomach. Symptoms can include feeling bloated and full, belching, flatulence, feeling sick, pain and discomfort in your upper abdomen, and heartburn. Symptoms usually occur after eating or drinking and can be more common at night (especially heartburn). Heartburn is the result of stomach acid travelling up your oesophagus (food pipe). This effect is known as acid reflux. The acid irritates the lining of your oesophagus, resulting in a burning feeling in your chest. Antacids work by neutralising stomach acid, reducing how much it can irritate the stomach lining.

How do I take an antacid?

You can use antacids to relieve indigestion or prevent it from occurring. To prevent indigestion, you should take an antacid with or soon after meals and just before going to bed. It is best to avoid drinking alcohol when taking an antacid because it can worsen your symptoms. Note, antacids are only recommended for short-term use. You should speak with your doctor if you have ongoing symptoms of heartburn or indigestion for more than two weeks. 

Should anyone not take an antacid?

Do not take an antacid product if you are allergic to any of the ingredients in it. Age restrictions vary between different antacid products, so make sure you follow the specific guidance for each product.

You should speak with your doctor or pharmacist before taking an antacid if you have liver or kidney problems, heart failure, or have been recommended to follow a diet low in calcium, sodium, or potassium. Not all antacid products are suitable if you are pregnant or breastfeeding, but Gaviscon and Rennie are.

Antacids can interact with other medications. If you take any prescription, over-the-counter, or herbal medications, you should ask your doctor or pharmacist whether it is safe to take them alongside an antacid. They may recommend you take your usual medications at a different time to an antacid.

Are there any side effects?

As with all medications, some people may experience side effects. If any side effects become bothersome, you should speak with your doctor or pharmacist. Potential side effects from antacids can include feeling sick, being sick, flatulence, stomach cramps, diarrhoea, and constipation.

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Dr Roger Henderson
Reviewed by Roger Henderson
Reviewed on 29.04.2024
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