Antacids are so-called drugs over the counter which counteract the acidity of the stomach giving immediate relief to pain, burning and other ailments caused by an excessive production of hydrochloric acid (gastric hyperacidity).

Antacids contain substances, such as aluminum and magnesium hydroxide, which react with the hydrochloric acid produced by the stomach and neutralize it without, however, intervening on the mechanisms that regulate acid secretion.

Acting locally, antacids are able to counteract the effects produced by excess acidity only temporarily, but not to resolve the causes.

They are, therefore, indicated for short-term relief in case of occasional ailments, such as those caused by the consumption of large or high-fat meals and other hard-to-digest foods. If the complaints are frequent and repeated and are associated with diseases characterized by excessive stomach acid, such as gastritis, gastroesophageal reflux disease and peptic ulcer, it is necessary to treat the underlying disease with targeted therapy (drugs more used, in these cases, are the so-called histamine H2 receptor antagonists, such as ranitidine and famotidine, and the proton pump inhibitors, such as, for example, omeprazole and pantoprazole, capable of reducing or blocking the production of hydrochloric acid by the stomach).

For more information on the active ingredients named in the contribution or in any case belonging to this class of drugs, you can visit the website of the Italian Medicines Agency (AIFA). To search for a drug using the trade name and not the active ingredient, click HERE . Inside the site you can find all the package leaflets of the drugs and also some additional information. If "revoked" is written next to the drug name, the drug is no longer on the market.

Types of antacids

The most common ingredients of the many antacid drugs on the market are:

  • aluminum hydroxide
  • magnesium hydroxide (and other magnesium compounds)
  • calcium carbonate
  • sodium bicarbonate

Most medicinal products use a combination of multiple antacids, some associate antacids with substances with different functions, such as simethicone or alginates (see below).

Sodium bicarbonate is the antacid that acts more quickly, but just as quickly exhausts its effects by forcing frequent intakes and, consequently, the ingestion of high quantities of sodium, which increases fluid retention.

Calcium carbonate has a slower speed of action than bicarbonate, but guarantees longer lasting effects.

Both sodium bicarbonate and calcium carbonate, reacting with the hydrochloric acid produced by the stomach, develop carbon dioxide, gas that dilates the stomach walls and can cause abdominal bloating (meteorism), flatulence and gas belching. To reduce these effects, in general, bicarbonate and carbonate are associated with simethicone (or dimethicone), an antifoam substance which favors the crushing and elimination of air bubbles produced by the release of carbon dioxide.

Aluminum hydroxide and magnesium hydroxide have a longer duration of action than bicarbonate and calcium carbonate, but have the disadvantage of altering intestinal motility causing, respectively, diarrhea and constipation. For this reason they are often used in combination. , so that the laxative effects of one counterbalance the astringent effects of the other.

Some medicines use a mixture of antacids and alginates (salts of alginic acid) to buffer the acidity associated with gastroesophageal reflux. In contact with hydrochloric acid, alginates form a gel which, floating on the contents of the stomach, hinders the ascent of acid secretion towards the esophagus by blocking reflux.

How to take antacids

Antacid medications are available in the form of capsules, tablets (chewable, effervescent or melt-in-the-mouth), effervescent granules and liquid solution. The liquid formulation is the one with the fastest action since it allows the antacid to distribute itself more evenly on the stomach walls.

The doses and how often you take antacids vary according to the drug used. It is therefore recommended to follow the instructions given in the package leaflet accompanying each pack of medicine or the directions of the doctor and / or pharmacist.

Generally, antacids are taken when needed, during or after meals, or before going to bed at night. Their effectiveness is greatest if they are taken at least 1 hour after meals, as ingested food slows stomach emptying and medications stay there longer.

It is preferable to avoid the consumption of alcohol which, by irritating the stomach, stimulates acid production and worsens the ailments.

If you use other drugs, it is always good to ask your doctor or pharmacist for advice before taking antacids as they could interfere with the absorption or elimination of other drugs, modifying their effects. In any case, to avoid possible reactions between different drugs, it is a good idea to take antacids at least 2-4 hours after other drugs.

Antacids should only be taken for short periods of time, not exceeding 2 consecutive weeks. Their prolonged use, in fact, could generate the so-called "reflex acidity", that is to say an overproduction of hydrochloric acid to compensate for the excessive reduction of acidity with a consequent aggravation of disturbances. If the pain and burning do not improve or even worsen after using the antacids, it is necessary to contact the treating doctor who may prescribe an alternative therapy or request further tests and investigations.

Undesirable (side) effects

When taken at the recommended doses and times, antacids rarely produce serious unwanted effects (side effects).

Disorders that can most commonly occur include:

  • diarrhea
  • constipation (constipation)
  • flatulence
  • stomach cramps
  • weakness
  • nausea
  • He retched

Usually, these are temporary and reversible disorders, in other words destined to disappear as soon as the use of antacids is discontinued. If the disorders persist, it is necessary to contact the family doctor.

More serious side effects are related to the use of high doses for prolonged periods or to the presence of serious diseases affecting the heart, liver and kidneys.

In case of excessive doses (overdose), it is necessary to consult your doctor immediately or go to the nearest emergency room.

Precautions for use

Antacids are safe drugs, but not suitable for everyone.They are, in fact, not recommended in various circumstances, which vary according to the active ingredient used.

To avoid possible damage to health it is important to read the package leaflet carefully.

Instead, it is necessary to obtain the opinion of the doctor before taking antacids in case of:

  • pregnant or breastfeeding breast
  • children under 12 years of age
  • severe heart, liver or kidney problems
  • need for a low-salt diet (sodium), as occurs in high blood pressure (arterial hypertension) and liver cirrhosis, as some antacids may contain high levels of sodium


NHS. Antacids (English)

Editor'S Choice 2022

Chili pepper

Chili pepper

Chilli is a plant belonging to the Solanaceae family grown all over the world and commonly used as a spice in kitchens all over the world. It is rich in minerals, vitamins and some polyphenols which can have beneficial effects

Bathing waters

Bathing waters

The "bathing waters", that is to say waters in which it is possible to 'bathe' and carry out recreational or sports activities, must be 'clean', i.e. free from both microbiological (due to the presence of microorganisms such as bacteria, viruses) and chemical contamination



Tachycardia consists of an increase in the number of heart beats which occurs even in conditions of rest and in the absence of physical activity, stress