Antacids are medications used to treat digestive symptoms, such as heartburn, sour stomach and acid indigestion. They raise the pH level (measure of the degree of acidity or alkalinity) of the stomach from highly acidic to a more neutral level. This neutralizes acid in the stomach and can provide substantial relief from symptoms.

The major types of antacids include:

• Aluminum and magnesium. Aluminum salts dissolve slowly in the stomach and work gradually, providing longer-lasting relief. Magnesium salts act quickly to neutralize acids.
  
  
• Calcium carbonate. Also known as chalk, it acts quickly and neutralizes acids for relatively long periods of time.
  
  
• Sodium bicarbonate. Also known as baking soda, it works quickly to neutralize acid.

Antacids are available in oral suspension, tablet, gel, lozenge and liquid form. They are available in a variety of flavors ranging from mint to assorted fruit. They begin to work within a minute, and can provide relief for time periods that range from 10 minutes to more than 90 minutes. However, they typically do not treat the underlying condition causing the symptoms. Therefore, patients who experience symptoms of digestive upset for more than two weeks should seek medical assistance.

Certain medications are known to interact poorly with antacids. In addition, antacids may worsen some pre-existing medical conditions, including colitis, constipation and hemorrhoids. It is recommended that children, elderly people and pregnant or nursing women consult a physician before taking antacids.

Antacids are medications that neutralize excessive stomach acid and help relieve symptoms related to heartburn (burning sensation caused by acid reflux into the lower end of the esophagus), sour stomach and acid indigestion (generalized abdominal discomfort). Some antacids also relieve symptoms related to stomach ulcers or duodenal ulcers.

The body needs to maintain a proper balance between its interior acidity and alkalinity. This is known as the body’s acid-base balance. The pH scale offers a measure of the acidity or alkalinity of the body’s blood – pH stands for potential of hydrogen. The scale ranges from 0 (most acidic) to 14 (most alkaline), with 7 being neutral. The body properly functions at a pH of about 7.4. However, the stomach is much more acidic than the rest of the body with a normal pH of less than 4. Failure to maintain a proper acid-base balance can result in various symptoms.

Antacids are intended to treat digestive upset by raising the pH level of the stomach from a highly acidic 2 to between 3 and 4. This can neutralize up to 99 percent of the acid in the stomach, leading to substantial relief from symptoms for most people. Antacids begin to work within a minute, and can provide relief that ranges from 10 minutes to more than 90 minutes.

Antacids are one of two major methods of treating digestive upset. The other involves histamine-2 (H2) blockers or proton-pump inhibitors (PPIs), which reduce the amount of acid produced in the stomach. Antacids tend to work more quickly than H2 blockers and PPIs, but the H2 blockers and PPIs provide longer-lasting relief.

Antacids are often used to treat mild to moderate forms of indigestion and heartburn, although they are less effective in treating frequent or severe forms of these symptoms. Antacids may also be used to treat conditions such as gastroesophageal reflux disease (GERD), peptic ulcers, gastritis and excess stomach gas (see Conditions treated).

Although antacids can often relieve symptoms of digestive upset, it is important to note that these symptoms may mask more serious conditions. For example, heart disease can sometimes cause symptoms of acute indigestion. Therefore, patients who experience symptoms of digestive upset for more than two weeks should consult a physician.

Most antacids contain at least one of four major ingredients. These include:

• Aluminum and magnesium. Aluminum salts dissolve slowly in the stomach and work gradually, providing longer-lasting relief. However, they may cause constipation. Magnesium salts act quickly to neutralize acids. In addition, they tend to act as a laxative. Because the effects of aluminum and magnesium balance each other so well, these types of antacids have long been considered an excellent treatment for digestive upset. However, in recent years there have been questions about the long-term safety of taking aluminum, which may deplete the body of phosphorus and calcium, increasing the risk of weak bones.
  
  
• Calcium carbonate. Also known as chalk, it acts quickly and neutralizes acids for relatively long periods of time. This ingredient is also beneficial because it provides calcium. Amounts of calcium usually range between 500 milligrams and 1,000 milligrams per dose. Calcium supplementation may be useful for those with osteoporosis. However, people should be sure not to exceed 2,000 milligrams per day, as it is possible to overdose on calcium.
  
  
• Sodium bicarbonate. Also known as baking soda, it works quickly to neutralize acid. People who belch after taking this antacid are releasing carbon dioxide gas. This is an indication that the antacid is working by neutralizing acid. However, taking too much bicarbonate can upset the body’s acid-base balance, leading to metabolic alkalosis (excess base in body fluids which can cause muscle spasms). In addition, the high level of sodium in this ingredient can cause problems for people with health conditions such as heart failure or high blood pressure (hypertension).

There are many varieties of antacids. They include:

Antacids are usually used to treat heartburn, sour stomach and/or acid indigestion resulting from a number of conditions including:

• Gastroesophageal reflux disease (GERD). A disorder in which stomach acid or bile flows back into the esophagus. Antacids may be effective in treating milder forms of this illness or as a supplement to other acid-reducing drugs.

• Peptic ulcers. These are erosions in the lining of the stomach or duodenum (first portion of the small intestine). Antacids can stop acids from damaging the stomach, thereby reducing pain and allowing the ulcers to heal. However, antacids are much less effective in ulcer healing than H2 blockers and PPIs.

• Gastritis. A group of conditions marked by inflammation of the stomach lining that causes burning pain in the upper abdomen. It may be accompanied by bloating, belching, nausea and vomiting.
• Excess stomach gas. Antacids that contain simethicone can help patients relieve excess stomach gas. However, antacids cannot reduce intestinal gas, a natural byproduct of digestion that is expelled from the body through belching or flatulence.

Antacids may also be used to relieve heartburn and indigestion associated with pregnancy. However, pregnant women are advised to consult their physician before taking antacids or any other medications. Antacids that contain simethicone can also help neutralize excess gas, whereas larger amounts of magnesium hydroxide and magnesium oxide are sometimes used as a laxative.

Patients who have too much of the mineral phosphate in their blood (hyperphosphatemia) may be treated with a combination of a low-phosphate diet and antacids such as aluminum carbonate and aluminum hydroxide. This combination is also used to prevent the formation of some types of kidney stones (a painful solid concentration in the kidney or urinary system).   

Recent research also indicates that antacids may help patients fight off the bacteria that causes gingivitis (gum disease).

Patients who take antacids often may experience a chalky taste in their mouths. Other side effects associated with antacids include:

• Mild constipation
• Diarrhea or a laxative effect
• Increased thirst
• Speckling or whitish discoloration of the stool
• Stomach cramps

Patients who take antacids should consult their physicians before taking any additional prescriptions, over-the-counter medications, nutritional supplements or herbal medications.

Certain medications are known to interact poorly with antacids. For example, use of antacids with the antibiotic tetracycline can decrease the effects of both medicines. Other medications that may interact poorly with antacids and cause one or both medicines to be ineffective include:

• Cellulose sodium phosphate (medicine used to prevent formation of calcium-containing kidney stones)
  
  
• Fluoroquinolones (medication used to treat bacterial infections)
  
  
• Isoniazid (medication used to treat or prevent tuberculosis)
  
  
• Ketoconazole (medication used to treat fungal infections)
  
  
• Methenamine (antibiotic used to treat urinary tract infections)
  
  
• Mecamylamine (antihypertensive used to treat high blood pressure)

Symptoms of overdose can be similar to the medication’s side effects, but are usually more severe. Patients who exhibit any of the following symptoms should seek medical assistance:

• Continuing feeling of discomfort
• Bone pain
• Severe and continuing constipation
• Persistent loss of appetite
• Mood or mental changes
• Muscle pain or twitching
• Nausea or vomiting
• Nervousness and restlessness
• Unusual tiredness or weakness
• Slow breathing
• Swelling of wrists or ankles
• Excessive weight loss
• Difficult or painful urination
• Irregular heartbeat
• Dizziness or lightheadedness

Antacids may be used to relieve heartburn and indigestion associated with pregnancy. However, women who are pregnant, thinking of becoming pregnant or breastfeeding should not use antacids without first consulting a physician. There have been no significant human or animal studies regarding the effects of antacids on expectant mothers and their fetuses. However, there have been reports that taking high doses of antacids during pregnancy may cause side effects in babies after birth. In addition, pregnant women who tend to retain water should avoid medications with high levels of sodium (salt), such as antacids.

Antacids containing aluminum, calcium or magnesium may pass into breast milk, but have not been reported to cause problems in nursing infants.

Preparing questions in advance can help patients to have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following antacid-related questions:

1. Are antacids appropriate for my condition?
   
   
2. Which type of antacid would you recommend for me?
   
   
3. How often can I take antacids?
   
   
4. How soon can I expect relief from my symptoms?
   
   
5. Is it possible for me to take too many antacids?
   
   
6. Will antacids interact with any prescription medications I am taking?
   
   
7. Are there any over-the-counter medications or supplements I should avoid when taking antacids?
   
   
8. Should I choose an antacid with calcium? Is it possible for me to get too much calcium?
   
   
9. Are there any potential side effects of antacids that I should immediately report to a physician?
   
   
10. I’m pregnant. Is it OK for me to take antacids?