Gaviscon: heartburn and indigestion relief explained

Gaviscon is a brand of alginate remedy, not a proton pump inhibitor. It is used for heartburn and indigestion, the burning that comes from acid travelling up from the stomach into the food pipe.

It is bought without a prescription in shops and pharmacies for ages 12 and over. Prescription versions exist for certain formulations and for younger children, and the NHS says it should only be given to under-12s when a doctor has prescribed or recommended it.

When alginic acid meets stomach acid it makes a foam, and that foam floats on top of whatever is in the stomach. It acts as a physical barrier, so if reflux happens, what comes up is mostly the foam rather than acid. Gaviscon also contains an antacid that helps with pain from too much stomach acid.

The NHS says it usually starts working soon after you take it. Because it acts at the surface of the stomach contents, it is taken after meals, when there is food to float on, and at bedtime.

For those aged 12 and over the NHS gives 10 ml to 20 ml of the liquid after meals and at bedtime, up to four times a day; 10 ml four times a day for Gaviscon Advance; or 2 to 4 tablets, up to four times a day. Follow the box or your pharmacist for the product you have.

Liquid is measured with the supplied spoon, tablets must be chewed rather than swallowed whole, and the infant powder is mixed with cooled boiled water or formula.

• For occasional heartburn, take it only when needed; for regular heartburn, up to four times in a day is the limit.

• If a dose is missed, skip it and carry on as usual. Do not double up.

• Taking too much may cause wind and bloating but rarely serious harm. Seek advice if you are concerned.

• If you have been on it for a long time on a doctor's advice, ask before stopping, since symptoms can return.

Ask a pharmacist or doctor before use if you have had an allergic reaction to Gaviscon or any medicine, have been told to follow a low-calcium or low-salt diet, or have kidney, liver or heart disease. People with phenylketonuria and those with low blood phosphate should also check.

Gaviscon is a short-term fix. If symptoms last beyond a week, the NHS suggests seeing a doctor, who may want to do tests or try another medicine.

Most people have no side effects. Mild ones are feeling or being sick, constipation and diarrhoea, and they normally stop when you stop taking it. Speak to a doctor or pharmacist if they persist.

A serious allergic reaction is possible but rare. Call 999 for swelling of the lips, mouth, throat or tongue, wheezing or severe breathing trouble, a tight throat, blue, grey or pale skin, sudden confusion or fainting. Children may go limp or floppy. Do not drive yourself to hospital.

Suspected side effects can be reported to the Yellow Card scheme.

Alginates can interfere with how other medicines are absorbed, so the NHS says to leave 2 hours between Gaviscon and antihistamines, quinolone and tetracycline antibiotics, iron tablets, antifungals, beta blockers, penicillamine, steroids, antipsychotics, chloroquine, estramustine, bisphosphonates and levothyroxine.

For pain, paracetamol can be taken at the same time as Gaviscon. Ibuprofen and aspirin can make indigestion worse and need a conversation with a pharmacist first. There are no known problems with herbal remedies and supplements.

Gaviscon can be used in pregnancy if you follow the instructions and stay within the recommended amount, and it is safe while breastfeeding without being expected to affect the baby. If it does not work, ask a pharmacist or doctor about alternatives. There is no evidence of an effect on fertility.

It does not affect driving or cycling. Alcohol does not change how it works but stimulates acid, so symptoms may feel worse. Smaller meals, avoiding fatty and spicy food, stopping smoking, leaving three hours between a meal and lying down and propping up the head of the bed all help.