What are antacids?
Antacids are a type of medicine that work to neutralise your stomach acid and help relieve indigestion and heartburn or acid reflux. They can also be used to relieve symptoms of a stomach ulcer and gastritis.
They come in liquid and chewable tablet form and can be bought in most supermarkets and pharmacies.
Keep reading to find out which antacid will work best for you, how and when to take them and the precautions and side effects you need to know.
Which type of antacid is right for you?
Which antacid is best for you depends on your symptoms and you may also want to think about the side effects of each type. Your pharmacist or doctor will be able to recommend the most effective antacid for you.
Things to consider when you choose your antacid:
- liquid or tablet? – liquid antacids tend to work more quickly and can be more effective, but tablets may be more convenient
- if you have reflux – look for antacids that also contain an alginate to help protect your gullet (oesophagus) from stomach acid
- if you have flatulence – look for an antacid that contains simeticone that will also help relieve any wind
- if you’re pregnant – avoid antacids that contain sodium bicarbonate, as this ingredient could affect the baby - from your pharmacy or doctor? – if your symptoms are mild and infrequent, antacids from your pharmacy will probably do the trick. If you’ve had symptoms for a long time, you should see your doctor so they can look into what might be causing your indigestion and give you prescription medicine, or do further tests if needed
- if you have any health conditions or are taking other medication – you should speak to your pharmacist or doctor about which antacid is safest for you
How to take antacids
You should always take antacids as directed on the packaging or in the information leaflet provided. Do not take more than the recommended daily dose.
Other handy things your pharmacist or doctor might suggest include:
- take your antacids when you have symptoms, or think you might get them
- if your symptoms are triggered by certain foods, take them just before or after eating. It’s thought the effects of antacids may last longer if you take them with food too
- if you have symptoms at night, take your antacids just before you go to bed and without food
- if you’re taking other medications, it’s important to check that antacids won’t affect how well they work. In most cases, you should try not to take any other medications within 2 to 4 hours before or after taking an antacid. But don't try and change the timings of your regular medications without checking with your pharmacist or doctor first
- avoid drinking alcohol and taking antacids as alcohol can worsen your indigestion symptoms
Who shouldn’t take antacids?
Antacids are safe for most people, but there are some exceptions. Speak to your doctor or pharmacist before taking antacids if you:
- are pregnant or breastfeeding
- have liver disease, kidney disease, kidney stones or heart failure
- are on a low sodium diet
- are taking calcium or iron supplements
- are on any other medications
Side effects of antacids aren’t common - look out for key ingredients
When they're only taken occasionally and at the recommended dose, antacids don’t usually cause any side effects.
You can reduce your risk of side effects by making sure you take antacids at the recommended dose, and at the right times as indicated in the information leaflet.
Side effects also depend on the ingredients in the antacid you’re taking and your health history or the condition you’re using it for.
Antacids are available under a number of different brand names but common ingredients are aluminium, calcium, sodium and magnesium.
Side effects you may have from these ingredients include:
- diarrhoea or constipation – antacids containing magnesium can have a laxative effect, while those containing aluminium may cause constipation. Antacids that contain both magnesium and aluminium are less likely to cause these side effects as they balance each other out
- fluid retention – antacids containing sodium bicarbonate may cause swelling in the feet, ankles, and hands
- acid rebound – if you take antacids containing calcium for a long time on high doses, it can lead to rebound acid secretion (a surge of acid) once you stop taking them
- nausea, vomiting or kidney stones – high doses of calcium-containing antacids taken over a long time can cause hypercalcaemia (too much calcium) and alkalosis (too little acid in the body). This is rare but can cause nausea, vomiting and kidney stones
If you have any of these side effects you should stop taking antacids straight away. Speak to your pharmacist or doctor if your symptoms continue.
When to see a doctor
You should see or talk to your doctor if you’re taking antacids and your symptoms are getting worse, not going away or you’re getting side effects.
It’s always a good idea to tell your doctor if you start taking a new medication of any type, especially if you’re taking any other medicines at the same time.
You can also use the Healthily Smart Symptom Checker if you’re worried about any of your symptoms.
Your health questions answered
What are natural antacids?
Answered by: Healthily’s medical team
Some home remedies like certain foods and drinks are described as natural antacids. There’s not much evidence to prove that these actually work or are any better than antacids, but they’re generally safe to try. Find out which foods and drinks can help relieve heartburn and indigestion.
