Antacids are medicines that counteract (neutralise) the acid in your stomach. They are used to relieve indigestion and heartburn.
There are many different types of antacids.
They come as liquid or chewable tablets. You can buy them from pharmacies and shops without a prescription.
Common types of antacids
Common brand names include Rennie, Gaviscon, Maalox, Bisodol, and Milk of Magnesia.
Some antacids are named after their main ingredient.
These include:
- aluminium hydroxide
- magnesium carbonate
- magnesium trisilicate
- magnesium hydroxide
- calcium carbonate
- sodium bicarbonate
Some antacids contain other medicines, such as:
- alginate - this coats your food pipe with a protective layer
- simeticone - this helps reduce bloating and farting (flatulence)
Uses of antacids
Antacids may help if you have:
- indigestion
- heartburn, acid reflux or gastro-oesophageal reflux disease (GORD)
- a stomach ulcer
- gastritis (inflammation of the stomach lining)
They can relieve your symptoms for a few hours. But they do not treat the underlying cause.
Long-term use of antacids is not recommended. Taking antacids for a long time may hide the signs of a more serious problem.
Talk to your GP if you are taking antacids often.
Check if you can take antacids
Antacids are safe for most people, but they are not suitable for everyone. Some antacids are not recommended for children.
Check with a pharmacist or GP before giving an antacid to a child age 12 or under.
Also check before taking an antacid if you:
- are taking other medicines
- have liver disease, kidney disease or heart failure
- need to control how much salt is in your diet - due to a condition such as high blood pressure
- have high levels of calcium in your blood
- have low levels of phosphate in your blood
Pregnant or breastfeeding
Most antacids are safe to take if you are pregnant or breastfeeding. But talk to a pharmacist or GP before taking them.
How and when to take antacids
Check the instructions on the packet or leaflet to see how much of the antacid to take and how often. This varies depending on which one you're taking.
Use antacids when you have symptoms or think you will get them soon. For most people, the best time to take them is with or soon after meals, and before going to bed.
Doses for children may be lower than for adults.
Talk to your GP or pharmacist if you take more than the recommended dose and start to feel unwell.
Eating and drinking
It's best to take antacids with food or soon after eating. This is when you're most likely to get indigestion or heartburn.
The effect of the medicine may also last longer if you take it with food.
You can drink alcohol while taking antacids. But alcohol can irritate your stomach and make your symptoms worse.
Side effects of antacids
Antacids do not have many side effects. But only take them from time to time and at the recommended dose.
Check the instructions on the packet or leaflet to see how much of the antacid to take and how to use the medicine.
There are things you can do to manage common side effects:
Diarrhoea
Drink lots of water to avoid dehydration. Signs of dehydration include peeing less than usual or having dark, strong-smelling pee.
Do not take any medicines to treat diarrhoea without speaking to a pharmacist or GP.
If you take the combined contraceptive pill or the progestogen-only pill and you have severe diarrhoea for more than 24 hours, your contraception may not protect you from pregnancy. Check the pill packet for advice.
Constipation
Try to get more fibre into your diet, such as fresh fruit and vegetables and cereals. Drink plenty of water. Try to exercise more regularly, for example by going for a daily walk or run.
If this does not help, talk to your pharmacist or GP.
Farting (flatulence)
Avoid foods that cause farting, like lentils, peas, beans and onions. It might also help to eat smaller and more frequent meals, eat and drink slowly, and exercise regularly. Some pharmacy remedies, such as simeticone, may relieve farting.
Stomach pain cramps
Try to rest and relax. It can help to eat and drink slowly and have smaller, more frequent meals. Putting a heat pad or covered hot water bottle on your stomach may also help. If you are in a lot of pain, speak to your pharmacist or GP.
Feeling sick or getting sick (vomiting)
Stick to simple meals and do not eat rich or spicy food.
Try drinking small, frequent sips of water. Speak to a pharmacist if you have signs of dehydration, such as peeing less than usual or having dark, strong-smelling pee.
Do not take any medicines to treat vomiting without speaking to a pharmacist or GP.
If you take contraceptive pills and you're being sick, your contraception may not protect you from pregnancy. Check the pill packet for advice.
Any side effects should stop when you stop taking the medicine.
Talk to a pharmacist or a GP if side effects do not improve or are bothering you. You may need to switch to another medicine.
Serious allergic reaction
A serious allergic reaction (anaphylaxis) to antacids is rare. But go to an emergency department (ED) if you have symptoms of a serious allergic reaction.
Emergency action required: Call 112 or 999 or go to an ED straight away if:
- you get a rash or itching
- your face, lips, tongue or throat start to swell
- you feel short of breath or have difficulty breathing
Stop taking the antacids immediately.
Read the patient information leaflet that comes with your medicine for a full list of side effects.
Non-urgent advice: Find your patient information leaflet
Your patient information leaflet is the leaflet that comes with your medicine. You can find a digital version of the leaflet online.
Report side effects
You can report any suspected side effects to the Health Products Regulatory Authority (HPRA): report an issue - hpra.ie
Taking antacids with other medicines
Antacids can affect how well other medicines work. Sometimes, they can stop other medicines working properly.
Talk to a pharmacist or GP about taking antacids if you are taking other medicines or supplements.
Do not take other medicines within 2 to 4 hours of taking an antacid. The antacid may affect how they work.
Fact check
This content was fact checked by a pharmacist, a GP, the National Medication Safety Programme (Safermeds) and the Health Products Regulatory Authority (HPRA).
