Antacids: Indications, Mechanism of Action, Side Effects and Formulations

They are substances that neutralize stomach acids and are used to relieve heartburn, indigestion, or an upset stomach.

Antacids neutralize the acid made by your stomach. They are commonly used in conditions where it is useful to neutralize the acid produced in the stomach.

For example, for acid reflux that causes heartburn . Most people who take antacids do not develop any side effects.

Antacids include aluminum hydroxide, magnesium carbonate, and magnesium trisilicate. These come in various brands and are available in tablets and liquids.

Some antacids are combined with another medicine called simethicone that helps reduce gas ( flatulence ).

Another group of medications called alginates are found in some brands of antacid medications. Alginates are added to help protect the lining of the esophagus from stomach acid.

Alginates include sodium alginate and alginic acid. They are present in antacid medications with various brands.

Medical uses

Antacids are available without a prescription and are taken by mouth to quickly relieve heartburn, the main symptom of gastroesophageal reflux disease, and also indigestion.

Some people use antacids as a preventive measure after a large meal, or if they have eaten something that has previously triggered indigestion symptoms. Others take an antacid before bed, if so when symptoms usually appear.

Treatment with antacids is only symptomatic and only justified for minor symptoms.

Antacids are different from acid-lowering drugs, such as H2 receptor antagonists or proton pump inhibitors, and they do not kill the Helicobacter pylori bacteria, which cause most ulcers.

What conditions do antacids treat?

Antacids can be used:

To reduce the symptoms of acid reflux which can cause heartburn or inflammation of the esophagus (esophagitis). These conditions are sometimes called gastroesophageal reflux disease (GERD).

In other conditions where it is useful to neutralize stomach acid. For example, for occasional episodes of indigestion (dyspepsia).

Before the discovery of other more modern medicines, antacids were commonly used for the above conditions. They were also used to help heal ulcers in the stomach and duodenum.

Modern medicines called proton pump inhibitors and H2 receptor antagonists (commonly called H2 blockers) are now more widely used for these conditions. They are much more effective than antacids.

Unlike antacids, which simply neutralize acid for a short period of time, these modern drugs work by reducing the amount of acid the stomach produces.

However, antacids still have a place. They are most often used to provide quick relief from symptoms caused by stomach acid. In particular, in people who have occasional episodes of mild dyspepsia or heartburn.

Is it bad to take too many antacid pills?

If you take antacid pills regularly, you definitely want to break this habit. First of all, there are many different types of antacids with ingredients that, in high doses, can have nasty side effects.

Some contain calcium, magnesium, or aluminum; Overloading the body with these substances can cause constipation or diarrhea. Other antacids have baking soda and may not be suitable for long-term use by people with high blood pressure or those who watch their salt intake.

Second, antacids work by neutralizing stomach acid to help temporarily relieve heartburn, an upset stomach, or indigestion, but they don’t treat the actual health problem that triggers those symptoms.

Although an upset stomach or indigestion is commonly linked to acid reflux, the discomfort can also be due to a peptic ulcer or gallstones, and each of these underlying health problems has its own course of treatment.

Also, masking your symptoms with antacids for too long could lead to an even bigger health problem down the road; for example, long-term acid exposure associated with acid reflux could damage the esophagus.

Be proactive and talk to your doctor about when and why you come across antacids, so they can give you a concrete diagnosis and recommend the best solution.

How do antacid tablets work?

As with any over-the-counter medicine, different products do different things.

Your stomach normally produces acid, this acid is corrosive so your body produces a natural mucosal barrier that protects the stomach lining from wearing away (eroding).

While most focus on balancing acid levels in the stomach, some cover the throat with a protective layer to lessen the impact of acid reflux, while others deal with other indigestion symptoms, such as bloating or flatulence.

In some people, this barrier may have broken down, allowing acid to damage the stomach and cause an ulcer. In others, there may be a problem with the muscle band in the upper part of the stomach (the sphincter) that keeps the stomach tightly closed.

This can allow acid to escape and irritate the throat (esophagus). This is called acid reflux, which can cause heartburn and / or inflammation of the esophagus (esophagitis).

Antacids work by counteracting (neutralizing) the acid in the stomach. This can help relieve pain associated with ulcers and the burning sensation in acid reflux.

When antacids work on stomach acid, they can produce gas that can cause gas (flatulence). Simethicone helps stop this sparkling effect and can sometimes be included in antacid medications.

Many of the common antacids also include alginates. Most alginates work by forming a gel that floats on top of the stomach contents. The gel acts as a protective barrier, preventing stomach acid from irritating the esophagus.

Side effects

It is important to understand that the proper use of antacids is unlikely to produce significant side effects in most people.

But long-term use of antacids can cause effects on the digestive system, along with other organs as well.

Of course, taking antacids when you have heartburn and need them is not bad, but they should only be a temporary solution. They are not intended for permanent, daily use.

The most common are diarrhea, constipation, and belching.

Versions with magnesium can cause diarrhea and brands with calcium or aluminum can cause constipation and, in rare cases, long-term use can cause kidney stones.

Antacids that contain both magnesium and aluminum can balance these effects and thus minimize any possible side effects of diarrhea or constipation. Long-term use of aluminum versions can increase the risk of osteoporosis.

For a complete list of all the side effects and possible interactions associated with your medication, see the leaflet that comes with your medication.

If you are taking antacids, you should avoid taking them at the same time as you take other medications. This is because antacids can affect the absorption of other medications.

We often think of antacids as totally safe medicine, but as with most medicines, there is still the risk of unwanted side effects.

So before taking antacids in any form, you’ll want to check with a doctor to make sure you’re not taking more than your body can handle.


Constipation is one of the most common symptoms of antacid overuse. It is usually seen with calcium, as well as with aluminum antacids. ‘ And the backup may not disappear so easily.

Constipation is not just a fleeting symptom, it tends to continue while antacids are used. If this happens, it is a good idea to completely switch to another type of medicine, such as a proton pump inhibitor.

Plus, you might get hit at the opposite end of the spectrum – antacids can also cause diarrhea, primarily antacids that contain magnesium.

Diarrhea is usually short-lived, but can recur with continued antacid use. Either way, those hours spent in the bathroom won’t feel too good.

Muscle problems

Muscle contractions, general weakness, and even muscle tenderness and pain are the most common complaints. This is due to the effects on the levels of calcium, magnesium, and phosphorus in the bloodstream.

In simple terms, any change in the levels of various levels of electrolytes can have an adverse impact on muscle and nerve function, he explains, so taking antacids in high doses or very casually can upset the body’s balance and cause some symptoms. of strange musculature.

The severity of symptoms is influenced by the amount of antacids and the duration of use, so if you start to notice anything strange, consult your doctor.

Respiratory problems

Breathing slower could also be a sign that you’re going overboard on antacids. This effect occurs if you consume too many that contain sodium bicarbonate or calcium carbonate, which can raise the pH in your bloodstream.

As the pH in the bloodstream increases, the body compensates for the more alkaline environment, which reduces the respiratory or respiratory rate.

When breathing slows down excessively, it could lead to a build-up of carbon dioxide, leading to fatigue or drowsiness. If this change in breathing persists, it could also interfere with your daily life and productivity.

Risk of infections

While gastric acid helps digest food, it also protects the body by destroying the bacteria that are contained within food and beverages. So when there is too much antacid present, it can be troublesome.

Excessive neutralization of stomach acid allows bacteria to survive in the gastrointestinal tract. In essence, this weakens one of the body’s main defense mechanisms.

This could allow bacteria to contribute to gastroenteritis, as well as diarrhea due to various types of bacteria. It could also increase the risk of upper respiratory disease.


Overuse of antacids that contain calcium carbonate can lead to hypercalcemia, or a condition known as milk-alkali syndrome.

This syndrome was originally recognized in the 1920s during the administration of the Sippy, milk and bicarbonate regimen, to treat peptic ulcer disease.

Kidney stones

Antacids that contain calcium can also increase the excretion of calcium in the urine, which in turn can lead to the formation of kidney stones.

What are those? A kidney stone is a hard, crystalline mineral formed and embedded in the kidney or urinary tract, “he explains. Kidney stones can cause blood in the urine and pain in the lower back or side.

They can be painful, and can even cause a spasm of the ureter (which connects the kidney to the bladder) that blocks the passage of urine, he says.

People with kidney disease should also avoid taking antacids, especially those that contain aluminum, as their impaired kidney function can lead to a toxic level of aluminum that builds up in the bloodstream.


One of the main side effects of overuse of antacids is the increased risk of osteoporosis.

Antacids that primarily contain aluminum can weaken bones as they can remove vital salts such as calcium and phosphate from the body.

This can be particularly concerning for those who are at early risk, with osteopenia, or who have osteoporosis in their family history.

Other considerations

You should see your doctor if your symptoms worsen, or if you experience any of the following problems that may indicate a serious bowel disorder:

  • Vomiting blood : This may be fresh blood, but the disturbed blood in the vomit may look like coffee grounds. Doctors call this vomit coffee grounds.
  • Blood in your stool : This can be obvious blood, or it can make your stools black.
  • Involuntary weight loss
  • Difficulty swallowing – including food that gets stuck in the esophagus.
  • Persistent abdominal pain or persistent vomiting.

Mechanism of action

When excessive amounts of acid are produced in the stomach, the natural mucosal barrier that protects the stomach lining can damage the esophagus in people with acid reflux.

Antacids contain alkaline ions that chemically neutralize gastric acid in the stomach, reducing damage and relieving pain.

With the help of active ingredients like aluminum, calcium, magnesium, and baking soda, antacids work by changing gastric pH, making it less acidic.

This helps decrease irritation to the stomach, esophagus, or duodenum (part of the small intestine that connects to the stomach).

Antacids can help treat gastroesophageal reflux disease (GERD), gastritis, and peptic ulcer by covering the esophagus and stomach, to reduce contact between gastric acid and the surface layer of the stomach lining.

Formulations and brands

Antacids can be formulated with other active ingredients such as simethicone to control gas or alginic acid to act as a physical barrier against the acid.


Effervescent tablets are tablets that are designed to dissolve in water and release carbon dioxide.

Common ingredients are citric acid and baking soda, which react when they come in contact with water to produce carbon dioxide.

Effervescent antacids can also contain aspirin, sodium carbonate, or tartaric acid.

The best known brands are Alka-Seltzer in the United States, along with Eno and Andrews in the United Kingdom.


Under the generic name of algeldrate, aluminum hydroxide is used as an antacid.

Aluminum hydroxide is preferred over other alternatives such as sodium bicarbonate because Al (OH) 3, being insoluble, does not increase the pH of the stomach above 7 and therefore does not trigger the secretion of excess stomach acid.

Brands include Alu-Cap, Aludrox, Gaviscon, and Pepsamar. In 2016, Gaviscon was one of the best-selling over-the-counter medicines sold in Britain, with sales of £ 62 million.

It reacts with excess acid in the stomach, reducing the acidity of the stomach contents, which can alleviate the symptoms of ulcers, heartburn or dyspepsia.

These products can cause constipation because aluminum ions inhibit smooth muscle cell contractions in the gastrointestinal tract, slowing down peristalsis and lengthening the time required for stool to pass through the colon.

Some of these products are formulated to minimize these effects by including equal concentrations of magnesium hydroxide or magnesium carbonate, which have counteracted laxative effects.

Can I buy antacids or do I need a prescription?

You can buy most brands of antacids in pharmacies, or you can get them with a prescription.

When is the best time to take antacids?

Antacids are often taken to relieve symptoms or when symptoms are expected. Your doctor or pharmacist will advise you on the necessary dose and how often to take it. Read the brochure that comes with your particular brand for more information.

How fast do antacids work?

In general, antacids provide quick relief for problems like heartburn caused by reflux. However, relief from symptoms may be short-lived.

How long does the treatment take?

Your doctor may prescribe an antacid to put you on standby, so that you only take it to relieve your symptoms when they occur, rather than every day. Read the brochure that comes with your particular brand for more information.

Who can and cannot take antacids?

A complete list of people who should not take antacids is included with the information leaflet that comes in the medicine package. If you are prescribed or bought an antacid, read this to make sure you can safely take it.

Natural alternatives to antacids

Around 40% of the UK population suffers from some form of indigestion each year. The most common short-term treatment method for indigestion symptoms is antacids, but could a natural alternative be just as effective?

Digestive enzymes

Digestive enzymes occur naturally throughout the digestive system, including the salivary glands, stomach, pancreas, and small intestine.

They help speed up the digestion process by breaking down food faster and allowing your body to absorb all the nutrients. By doing so, you also help prevent acid build-up.

Unfortunately, some people do not have enough naturally-occurring digestive enzymes to be effective, which can lead to indigestion. In these cases, you can take a supplement with (or right after) each meal to prevent your symptoms from worsening.

However, it is worth remembering that in some cases low digestive enzymes can be caused by a serious health condition, such as:

It is worth talking to a doctor before making the decision to supplement with digestive enzymes. If you go down this route, there are several different products available and some are more effective than others. Talk to a doctor or pharmacist about the best option for you.


We often think of probiotics as ‘friendly bacteria’, which outcompete the ‘bad bacteria’ in the gut and help with digestion.

You can buy probiotic supplements, but it is also possible to get them naturally in your diet. Treat:

  • Yogurt, kefir, or soft cheese made from goat’s or sheep’s milk. Fermented vegetables, such as kimchi, sauerkraut, pickles, and miso (which is made with fermented soybeans).
  • Apple Cider Vinegar : Although the effectiveness of this is based on word of mouth rather than clinical studies, some people find it helps their digestion by adding a couple of teaspoons to a glass of water or pouring apple cider vinegar over salad .

Chamomile tea

Chamomile is known for its potentially calming effect on your mental health. What you may be less aware of is its potential to have the same effect on your stomach.

While it doesn’t necessarily prevent acid reflux from occurring, it can reduce subsequent swelling in the throat and has helpful pain relieving properties that can be helpful in calming symptoms.

Chamomile’s ability to relieve stress also addresses one of the main causes of indigestion.


Ginger is an effective antiemetic, which means that it can prevent nausea and vomiting.

It does this by reducing the number of stomach contractions you have, which is helpful after a large meal as it prevents acid from being pushed into your esophagus. Like chamomile, it also has anti-inflammatory properties.

You can have raw ginger if you like, but it’s often tastiest brewed into a tea, or added to recipes like stir fries.

You shouldn’t have more than four grams of ginger per day. After all, it is a spice, and we know that spicy food can trigger indigestion. Too much will make your indigestion and heartburn worse.

Rest and relaxation

As the old saying goes, prevention is better than cure. First of all, there are many things you can do to reduce your chances of indigestion or heartburn.

Stress is a known trigger for indigestion, so if you’ve been feeling overwhelmed lately, this should be one of the first things you tackle. You can also try:

Eat smaller portions, eat more slowly, avoid foods that you know can cause indigestion.

Stop smoking, as cigarettes can weaken the opening between your throat and your stomach, allowing acid to seep back in more easily.

Avoid large meals before bedtime, as lying down can put pressure on your stomach.

When to see a doctor

If you have frequent or severe episodes of indigestion or heartburn, this could be a sign of an underlying health problem.

In this situation, it is best not to mask the problem by taking antacids. Talk to a doctor as soon as you can to explain your symptoms. They will be able to help you rule out or diagnose any problems that may be causing your indigestion.

It’s worth asking a doctor which antacid is best for you before committing to a purchase. They can also describe the most effective dose and explain how long you will need to take the medication.