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Gaviscon (alginic acid)

On this page

  1. About Gaviscon
  2. Key facts
  3. Who can and cannot take Gaviscon
  4. How and when to take Gaviscon
  5. Side effects
  6. Pregnancy and breastfeeding
  7. Cautions with other medicines
  8. Common questions about Gaviscon

1. About Gaviscon

Gaviscon can be used to treat heartburn (acid reflux) and indigestion.

The medicine works by forming a protective layer that floats on top of the contents of your stomach. This stops stomach acid escaping up into your food pipe. Gaviscon also contains an antacid that neutralises excess stomach acid and reduces pain and discomfort.

Gaviscon comes as chewable tablets, or a liquid that you drink (in bottles or in sachets). It also comes as a powder for babies and children under 2 years old.

You can buy Gaviscon from pharmacies and supermarkets. Some kinds of Gaviscon are available on prescription.

2. Key facts

  • You'll usually take Gaviscon after meals and at bedtime.
  • You should feel the benefit of taking Gaviscon soon after taking it, and it will last for around 4 hours.
  • It's safe to take paracetamol at the same time as Gaviscon but do not take ibuprofen or aspirin with it.
  • If you've bought Gaviscon without a prescription, do not take it for longer than 7 days without checking with a doctor.
  • There are different types of Gaviscon. Ask your doctor or pharmacist which one is best for you.

3. Who can and cannot take Gaviscon

Gaviscon can be taken by most adults and children aged 12 and over.

If your baby or child has problems with reflux or indigestion, talk to your doctor as soon as you can. Only treat them with Gaviscon if their doctor prescribes it.

To make sure this medicine is safe for you, tell your doctor or pharmacist if you have:

  • ever had an allergic reaction to Gaviscon or any other medicines
  • been advised to eat a low calcium or low salt (low sodium) diet
  • kidney or heart disease
  • a rare, inherited illness called phenylketonuria
  • low levels of phosphate in your blood

Important: Children under 12

Never give Gaviscon to children under 12, unless their doctor prescribes it.

4. How and when to take Gaviscon

You'll usually take Gaviscon tablets and liquid up to 4 times a day. It's best to take it after meals and at bedtime. This is usually when the pain and discomfort is at its worst. But if your doctor has prescribed Gaviscon, take it when they tell you to.

Chew the tablets, do not swallow them whole. It's best to have a drink afterwards.

Mix Gaviscon powder (for babies and children under 2) with cool, boiled water or formula milk.


The dose depends on the type of Gaviscon you're taking. The liquid is usually one to two 5ml spoonfuls, up to 4 times a day. The tablets are usually 2 to 4 tablets, up to 4 times a day. Always check the packaging information.

Follow the instructions on the packaging or, if your doctor has prescribed it, take the dose they tell you to.

When to take Gaviscon

If you get occasional mild heartburn or indigestion, only take Gaviscon when you need it.

If you often have heartburn or indigestion, take Gaviscon regularly after meals and at bedtime, up to 4 times a day, whether or not you have symptoms.

If you've been taking Gaviscon for more than 7 days and you're still feeling uncomfortable or in pain, talk to your doctor.

What if I forget to take it?

If you usually take Gaviscon regularly but forget to take a dose, do not double your dose the next time. Just leave out the missed dose and take your next dose as normal.

If you forget doses often, it may help to set an alarm to remind you. You could also ask your pharmacist for advice on other ways to help you remember to take your medicine.

What if I take too much?

Taking too much Gaviscon may cause side effects such as wind and bloating (when your stomach feels tight and full of gas). This is unlikely to cause you any harm. If you are worried, talk to your doctor or pharmacist.

5. Side effects

Gaviscon is a very safe medicine. Most people who take it do not have any side effects. If you do get a side effect, it's likely to be mild and will go away when you stop taking Gaviscon.

Some types of Gaviscon may be more likely to make you feel sick or cause vomiting, constipation or diarrhoea because of their ingredients. Talk to your doctor or pharmacist if you notice any side effects that bother you or do not go away.

Serious allergic reaction

In very rare cases, it's possible to have a serious allergic reaction (anaphylaxis) to Gaviscon. This happens in less than 1 in 10,000 people.

Immediate action required: Call 999 now if:
  • your lips, mouth, throat or tongue suddenly become swollen
  • you're breathing very fast or struggling to breathe (you may become very wheezy or feel like you're choking or gasping for air)
  • your throat feels tight or you're struggling to swallow
  • your skin, tongue or lips turn blue, grey or pale (if you have black or brown skin, this may be easier to see on the palms of your hands or soles of your feet)
  • you suddenly become very confused, drowsy or dizzy
  • someone faints and cannot be woken up
  • a child is limp, floppy or not responding like they normally do (their head may fall to the side, backwards or forwards, or they may find it difficult to lift their head or focus on your face)

You or the person who's unwell may also have a rash that's swollen, raised, itchy, blistered or peeling.

These can be signs of a serious allergic reaction and may need immediate treatment in hospital.

These are not all the side effects of Gaviscon. For a full list see the leaflet inside your medicines packet.


You can report any suspected side effect using the Yellow Card safety scheme.

Visit Yellow Card for further information.

6. Pregnancy and breastfeeding

You can take Gaviscon while you're pregnant or breastfeeding.

However, if you have indigestion, it’s best to try and treat it without taking a medicine. For example, it can help to:

  • eat smaller meals more often
  • avoid fatty or spicy foods
  • raise the head of your bed a little

If this does not work, your doctor or midwife may recommend a medicine like Gaviscon.

Non-urgent advice: Tell your doctor if you're:

  • trying to get pregnant
  • pregnant
  • breastfeeding

7. Cautions with other medicines

Some medicines must not be taken at the same time as Gaviscon. This is because the medicines can affect how the other medicine works.

Do not take Gaviscon within 2 hours before or after taking:

Taking Gaviscon with painkillers

It's safe to take paracetamol at the same time as Gaviscon. But do not take other painkillers, like ibuprofen or aspirin, with Gaviscon without talking to your doctor or pharmacist first. These can make your symptoms worse.

Mixing Gaviscon with herbal remedies and supplements

There are no known problems with taking herbal remedies and supplements alongside Gaviscon.

Important: Medicine safety

Tell your doctor or pharmacist if you're taking any other medicines, including herbal medicines, vitamins or supplements.

8. Common questions about Gaviscon

How does Gaviscon work?

Gaviscon is a type of medicine called a reflux suppressant.

Reflux is when stomach acid travels up your food pipe and gives you a burning feeling in your chest.

Reflux suppressants like Gaviscon contain alginic acid which is made from seaweed. Alginic acid makes a protective foam layer that floats on top of the contents of your stomach. This stops stomach acid escaping into your food pipe.

Gaviscon also contains an antacid that neutralises stomach acid and reduces pain and discomfort.

When will I feel better?

You should start to feel better soon after taking a dose of Gaviscon. The effect of 1 dose should last for around 4 hours.

If you buy Gaviscon, rather than having it prescribed by a doctor, and you do not feel better after taking it for 7 days, tell your doctor. They may want to do tests or try a different medicine.

Is it safe to take Gaviscon for a long time?

Gaviscon does not usually cause problems when you take it for a long time. Tell your doctor if you need to take it regularly for more than a week.

Are there other medicines similar to Gaviscon?

Yes, Acidex and Peptac are similar to Gaviscon.

These medicines are reflux suppressants. They work in the same way as Gaviscon, by reducing acid in your stomach and preventing excess acid escaping into your food pipe. They generally work as well as Gaviscon and have similar side effects. However, they may be given in different doses to Gaviscon.

Sometimes, if Gaviscon does not work or agree with you, your doctor or pharmacist may suggest another reflux suppressant. Like Gaviscon, you can buy Peptac or Acidex from pharmacies and supermarkets.

Are there other indigestion medicines?

There are a number of different medicines for indigestion and heartburn.

  • Antacids include Tums (calcium carbonate), Maalox and Milk of Magnesia. These relieve indigestion and heartburn by neutralising the acid in your stomach. They work quickly and make you feel better for a few hours. They're ideal if you occasionally get stomach acid problems. You can get antacids from pharmacies and supermarkets.
  • Proton pump inhibitors (PPIs) reduce the amount of acid your stomach produces. Most PPIs are available on prescription only. They include omeprazole and lansoprazole. You can buy the lowest strength omeprazole and esomeprazole from pharmacies.
Can I take Gaviscon with a proton pump inhibitor?

If your doctor has prescribed a proton pump inhibitor (PPI), such as lansoprazole, to reduce the amount of acid your stomach produces, you can take Gaviscon with it.

Is the Gaviscon I buy the same as on prescription?

Doctors can only prescribe some kinds of Gaviscon, not the full range available from pharmacies and supermarkets.

Different kinds of Gaviscon contain different ingredients. Speak to your doctor or pharmacist to make sure you get a medicine that suits you.

How do I stop taking Gaviscon?

Usually you can stop taking Gaviscon without reducing the dose first.

If you've taken Gaviscon regularly for a long time, talk to your doctor before you stop taking it. Stopping suddenly may mean that the acid stomach contents come up into your food pipe and make your symptoms come back.

Will it affect my fertility?

There's no clear evidence to suggest that taking Gaviscon will reduce fertility in either men or women.

Will it affect my contraception?

Gaviscon does not affect any type of regular contraception including the contraceptive pill.

However, it may reduce the effectiveness of one type of emergency contraception called Ellaone (ulipristal) if taken together.

It may be better to avoid taking Gaviscon a few hours before and after taking Ellaone, or use a different emergency contraceptive instead.

Can I drive or ride a bike?

Yes, taking Gaviscon should not affect your ability to drive or ride a bike.

Can I drink alcohol with it?

Alcohol does not affect the way Gaviscon works, but drinking alcohol makes your stomach produce more acid than normal. This can irritate your stomach lining and make your symptoms worse.

Can lifestyle changes help heartburn and indigestion?

Making a few changes to your diet and lifestyle may help if you have problems caused by too much stomach acid.

It can help if you:

  • keep to a healthy weight or lose weight if you need to – extra weight can put pressure on your stomach and make acid reflux worse
  • do not eat foods that can make your symptoms worse, including rich, spicy and fatty foods, and acidic foods like tomatoes, citrus fruits, salad dressings and fizzy drinks
  • cut down on caffeinated drinks, such as tea, coffee and cola, as well as alcohol and smoking
  • try not to eat for at least 3 hours before you go to bed
  • raise the head of your bed a little
  • quit smoking – you can call the NHS Stop Smoking Helpline on 0300 123 1044

Page last reviewed: 10 August 2021
Next review due: 10 August 2024