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Drug Treatment of Stomach Acid


Nimish Vakil

, MD, University of Wisconsin School of Medicine and Public Health

Last full review/revision Mar 2020| Content last modified Mar 2020
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Stomach acid plays a role in a number of disorders of the stomach, including peptic ulcer, gastritis, and gastroesophageal reflux disease (GERD). Although the amount of acid present in the stomach is usually normal in people with these disorders, reducing the amount of acid in the stomach is important in treating the damage to the stomach and intestines as well as in relieving symptoms.

Proton pump inhibitors

The proton pump is the name for the chemical process by which the stomach secretes acid. Proton pump inhibitors are the most potent of the drugs that reduce acid production. Proton pump inhibitors promote healing of ulcers in a greater percentage of people in a shorter period of time than do histamine-2 (H2) blockers and thus are typically preferred to H2 blockers for treating ulcers. They are used for severe forms of gastritis (such as when bleeding is present) and for severe GERD. Proton pump inhibitors are also very useful in treating conditions that cause excessive stomach acid secretion, such as Zollinger-Ellison syndrome.

Proton pump inhibitors can be given by mouth or by vein (IV). These drugs are usually very well tolerated but may cause diarrhea, constipation, and headache. Long-term use of proton pump inhibitors may cause reduced absorption of B12, iron, magnesium, and calcium.

Histamine-2 (H2) blockers

Histamine is a substance naturally produced in the body that has several roles. Histamine is one of the main substances responsible for allergic reactions, which is why antihistamines (histamine blockers) are given to people who are having an allergic reaction to something. Histamine also helps signal the body to produce stomach acid, which is why a certain type of antihistamine, called a histamine-2 blocker, is used to decrease stomach acid. Thus, H2 blockers are used for many of the same disorders as proton pump inhibitors.

H2 blockers are taken once or twice a day and can be given by mouth or by vein (IV). H2 blockers usually do not cause serious side effects. However, all H2 blockers may cause diarrhea, rash, fever, muscle pains, and confusion. Cimetidine may cause breast enlargement and erectile dysfunction in men. In addition, cimetidine and, to a lesser extent, the other H2 blockers may interfere with the body's elimination of certain drugs, such as theophylline for asthma, warfarin for excessive blood clotting, and phenytoin for seizures.


Antacids are chemical substances that neutralize stomach acid that has already been secreted and thereby raise the pH level in the stomach (make it less acidic). Antacids may be used alone for mild symptoms caused by stomach acid. But by themselves, antacids are not adequate treatment for serious acid-related disorders such as ulcers and severe gastritis. In those disorders, antacids are typically taken in addition to proton pump inhibitors or H2 blockers to help relieve symptoms in the early stage of treatment. Their effectiveness varies with the amount of antacid taken and the amount of acid a person produces. Almost all antacids can be purchased without a doctor's prescription and are available in tablet or liquid form. However, antacids can interfere with the absorption of many different drugs, so a pharmacist should be consulted about possible drug-drug interactions before antacids are taken.

Sodium bicarbonate (baking soda) and calcium carbonate, the strongest antacids, may be taken occasionally for fast, short-term relief. However, because they are absorbed by the bloodstream, continual use of these drugs may make the blood too alkaline (alkalosis), resulting in nausea, headache, and weakness. Therefore, these antacids generally should not be used in large amounts for more than a few days. These products also contain a lot of salt and should not be used by people who need to follow a low-sodium diet or who have heart failure or high blood pressure.

Aluminum hydroxide is a relatively safe, commonly used antacid. However, aluminum may bind with phosphate in the digestive tract, thereby depleting the body of calcium, reducing phosphate levels in the blood, and causing weakness, nausea, and a loss of appetite. The risk of these side effects is greater in people who have alcoholism, who are undernourished, and who have kidney disease, including those receiving dialysis. Aluminum hydroxide may also cause constipation.

Magnesium hydroxide is a more effective antacid than aluminum hydroxide. This antacid acts fast and neutralizes acids effectively. However, magnesium is also a laxative. Bowel movements usually remain regular if only a few tablespoons a day are taken. More than four doses a day may cause diarrhea. Because small amounts of magnesium are absorbed into the bloodstream, people with kidney damage should take magnesium hydroxide only in small doses. To limit diarrhea, many antacids contain both magnesium hydroxide and aluminum hydroxide.

Anyone who has heart disease, high blood pressure, or a kidney disorder should consult a doctor before selecting an antacid.

Other drugs for stomach acid

Sucralfate may work by forming a protective coating in the base of an ulcer to promote healing. It works well on peptic ulcers and is a reasonable alternative to antacids. Sucralfate is taken 2 to 4 times a day and is not absorbed into the bloodstream, so it causes few side effects. It may, however, cause constipation, and in some cases it reduces the effectiveness of other drugs.

Misoprostol may be used to reduce the likelihood of developing stomach and duodenal ulcers caused by NSAIDs. Misoprostol may work by reducing production of stomach acid and by making the stomach lining more resistant to acid. Older people, people taking corticosteroids, and people who have a history of ulcers or of complications resulting from ulcers are at higher risk of developing an ulcer when they take NSAIDs. These people can take misoprostol with food and their NSAID. However, misoprostol causes diarrhea and other digestive problems in 30% of people who take it. In addition, this drug can cause spontaneous abortions in pregnant women. Alternatives to misoprostol are available for people taking aspirin, NSAIDs, or corticosteroids. These alternatives, such as proton pump inhibitors, are just as effective for reducing the likelihood of developing an ulcer and cause fewer side effects.


Drugs Used to Treat Stomach Acid

Drug Type

Some Side Effects



  • Aluminum hydroxide

  • Calcium carbonate

  • Magnesium hydroxide

  • Sodium bicarbonate

Aluminum hydroxide: Nausea, headache, weakness, loss of appetite, and constipation

Magnesium hydroxide: Diarrhea

These drugs are used mainly to relieve symptoms, not as a cure.

Histamine-2 (H2) blockers

  • Cimetidine

  • Famotidine

  • Nizatidine

Rash, fever, diarrhea, muscle pains, and confusion

Cimetidine: May cause breast enlargement and erectile dysfunction in men and may interfere with elimination of certain drugs

The once-daily dose is taken in the evening or at bedtime. Doses taken in the morning are less effective.

Proton pump inhibitors

  • Esomeprazole

  • Lansoprazole

  • Omeprazole

  • Pantoprazole

  • Rabeprazole

Diarrhea, constipation, and headache

These drugs are usually well tolerated and are most effective means of reducing stomach acid.

Other drugs for stomach acid

  • Misoprostol

  • Sucralfate

Misoprostol: Abdominal cramping, spontaneous abortion, diarrhea

Sucralfate: May reduce absorption of other drugs, constipation

Misoprostol is rarely used for treatment of stomach disorders due to the side effects.

Sucralfate does not affect acid production but coats stomach ulcers to protect them from acid.

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