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By Marianne Belleza, R.N.

Learn about the different antacids in this nursing pharmacology study guide.

Antacids are used to chemically react with and neutralize the acid in the stomach. They can provide rapid relief from increased acid levels. They are known to cause GI alterations such as diarrhea or constipation and can alter the absorption of many drugs.

Table of Contents

Antacids: Generic and Brand Names

Here is a list of the most commonly encountered antacids and their brand names.

  • Antacids
    • aluminum salts (AlternaGel)
    • calcium salts (Oystercal, Tums)
    • magaldrate (Losopan, Riopan)
    • magnesium salts (Milk of Magnesia, others)
    • sodium bicarbonate (Bell-ans)

Disease Spotlight: Ulcer Disease

Erosions in the lining of the stomach and adjacent areas of the GI tract are called peptic ulcer.

  • Ulcer patients present with a predictable description of gnawing, burning pain often occurring a few hours after meals.
  • Many of the drugs that are used to affect GI secretions are designed to prevent, treat, or aid in the healing of these ulcers.
  • Further research led many to believe that, because acid production was often normal in ulcer patients, ulcers were caused by a defect in the mucous lining that coats the inner lumen of the stomach to protect it from acid and digestive enzymes.
  • Treatment was aimed at improving the balance between the acid produced and the mucous layer that protects the stomach lining.

What are Antacids?

Antacids are a group of inorganic chemicals that neutralize stomach acid.

  • Antacids are available OTC, and many patients use them to self-treat a variety of GI symptoms.
  • The choice of an antacid depends on adverse effects and absorption factors.

Therapeutic actions

The desired actions of antacids include the following:

  • Neutralize stomach acid by direct chemical reaction.
  • Symptomatic relief of an upset stomach associated with hyperacidity, as well as the hyperacidity associated with peptic ulcer, gastritis, peptic esophagitis, gastric hyperacidity, and hiatal hernia.


Antacids are indicated for the following:

  • Symptomatic relief of GI hyperacidity, treatment of hyperphosphatemia, prevention of formation of phosphate urinary stones.
  • Treatment of calcium deficiency, prevention of hypocalcemia.
  • Prophylaxis of stress ulcers, relief of constipation.


Many of these antacids are available in combination forms to take advantage of the acid-neutralizing effect and block adverse effects.

Route Onset Peak Duration
Oral Rapid 30 min 1-3 h
IV Immediate Rapid Unknown
Half-life (T1/2) Metabolism Excretion
unknown unchanged in urine

Contraindications and Cautions

The following are contraindications and cautions when using antacids:

  • Allergy. The antacids are contraindicated in the presence of any known allergy to antacid products or any component of the drug to prevent hypersensitivity reactions.
  • Co-morbidities. Caution should be used in the following instances: any condition that can be exacerbated by electrolyte or acid-based imbalance to prevent exacerbations and serious adverse effects; any electrolyte imbalance , which could be exacerbated by the electrolyte-changing effects of these drugs; GI obstruction which could cause systemic absorption of the drugs and increase adverse effects; renal dysfunction, which could lead to electrolyte disturbance if any absorbed antacid is neutralized properly.
  • Pregnancy and lactation. Antacids are contraindicated for pregnant and lactating women because of the potential for adverse effects on the fetus or neonate.

Adverse effects

Adverse effects when using antacids include:


Antacids can greatly affect the absorption of drugs from the GI tract.

  • Alkalinity. Most drugs are prepared for an acidic environment, and an alkaline environment can prevent them from being broken down for absorption or can actually neutralize them so that they cannot be absorbed.

Nursing considerations

Nursing considerations for a patient using antacids include the following:

Nursing Assessment

History taking and physical exam in a patient using antacids include:

  • Assess for possible contraindications and cautions: any history of allergy to antacids to prevent hypersensitivity reactions; renal dysfunction, which might interfere with the drug’s excretion; electrolyte disturbances, which could be exacerbated by effects of the drug; and current status of pregnancy or lactation due to possible effects on the fetus or newborn.
  • Perform a physical examination to establish baseline data before beginning therapy, determine the effectiveness of the therapy, and evaluate for any potential adverse effects associated with the drug.
  • Inspect the abdomen; auscultate bowel sounds to ensure GI motility.
  • Assess mucous membrane status to evaluate potential problems with absorption and hydration.
  • Monitor laboratory test results, including serum electrolyte levels and renal function tests, to monitor for adverse effects of the drug and potential alterations in excretion that may necessitate dose adjustment.

Nursing Diagnosis and Care Planning

Nursing diagnoses related to drug therapy might include the following:

  • Diarrhea related to GI effects.
  • Risk for constipation related to GI effects.
  • Imbalanced nutrition: less than body requirements related to GI effects.
  • Risk for imbalanced fluid volume related to systemic effects.
  • Deficient knowledge regarding drug therapy.

Nursing Implementation with Rationale

The nursing interventions for patients using antacids are:

  • Adequate drug absorption. Administer the drug apart from any other oral medications approximately 1 hour before or 2 hours after to ensure adequate absorption of the other medications.
  • Ensure therapeutic levels. Have the patient chew tablets thoroughly and follow with water to ensure that therapeutic levels reach the stomach to decrease acidity.
  • Perform diagnostic testing. Obtain specimens for periodic monitoring of serum electrolytes to evaluate drug effects.
  • Prevent imbalances. Assess the patient for any signs of acid-base or electrolyte imbalance to ensure early detection and prompt interventions.
  • Institute a bowel program. Monitor the patient for diarrhea or constipation to institute a bowel program before severe effects occur.
  • Ensure adequate nutritional status. Monitor the patient’s nutritional status if diarrhea is severe or constipation leads to decreased food intake to ensure adequate fluid and nutritional intake to promote healing and GI stability.
  • Provide patient support. Offer support and encouragement to help the patient cope with the disease and the drug regimen.
  • Educate the patient. Provide thorough patient teaching, including the drug name and prescribed dose, schedule for administration, signs and symptoms of adverse effects and measures to prevent or minimize them, warning signs that may indicate possible problems and the need to notify the health care provider immediately.


Evaluation of a patient using antacids include:

  • Monitor patient response to the drug (relief of GI symptoms caused by hyperacidity).
  • Monitor for adverse effects (GI effects, imbalances in serum electrolytes, and acid-base status).
  • Evaluate the effectiveness of the teaching plan (patient can name the drug and dosage, as well as describe the adverse effects to watch for, specific measures to avoid them, and measures to take to increase the effectiveness of the drug).
  • Monitor the effectiveness of comfort measures and compliance with the regimen.

    References and Sources

    References and sources for this Antacid Nursing Pharmacology Guide:

    • Karch, A. M., & Karch. (2011). Focus on nursing pharmacology. Wolters Kluwer Health/Lippincott Williams & Wilkins. [Link]
    • Smeltzer, S. C., & Bare, B. G. (1992). Brunner & Suddarth’s textbook of medical-surgical nursing. Philadelphia: JB Lippincott.
    Marianne leads a double life, working as a staff nurse during the day and moonlighting as a writer for Nurseslabs at night. As an outpatient department nurse, she has honed her skills in delivering health education to her patients, making her a valuable resource and study guide writer for aspiring student nurses.

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