H2 antagonists or H2 blockers are medications used in the management of many gastric diseases, such as stomach ulcers, gastroesophageal reflux disease (GERD), and heartburn. H2 antagonists work by reducing the amount of acid produced in the stomach.
H2 antagonists are usually taken by mouth and are available in different forms such as tablets, capsules, powder for suspension, and liquids. They can also be given intravenously in emergency cases or in patients who have difficulty swallowing, or those who are on a “nothing by mouth” order.
Some H2 blockers can be bought over-the-counter at lower dosages which can be taken up to 2 weeks. If there is no improvement in the acid reflux symptoms, the patient should seek the help of a healthcare provider.
Indications for H2 antagonists
H2 antagonists are given to a number of diseases, including:
- GERD
- Heartburn
- Gastric and duodenal ulcers
- Ulcers caused by non-steroidal anti-inflammatory drugs (NSAIDs)
- Upper gastrointestinal hemorrhage or bleeding
- Zollinger-Ellison syndrome or other gastric hypersecretory diseases
Actions of H2 antagonist
The cells in the lining of the stomach are stimulated by a chemical called histamine in order to produce hydrochloric acid (HCl). This acid is necessary to help break down and digest food in the stomach. However, too much HCl can lead to the corrosion of the natural mucous barrier that lines the stomach.
When this happens, gastrointestinal disorders such as gastric and duodenal ulcers may occur.
The acid may also irritate and damage the lining of the esophagus, which can result to heartburn or esophagitis (inflammation of the esophagus). H2 antagonists work by binding the histamine receptors to reduce the amount of HCl secreted in the stomach within 60 minutes of administering the medication.
H2 antagonists’ effect can last from 4 to 10 hours, thus the usual prescription for adults is 150 milligrams of an H2 blocker drug to be given twice a day.
H2 blockers are given as an alternative to proton pump inhibitors (PPIs). PPIs significantly reduce the amount of acid made in the stomach by blocking gastric proton pumps; however, research shows that long-term use of PPIs may have contributed to premature death in elderly patients and increased risks of bone fracture. Despite their ability to reduce stomach acid production better than H2 blockers, PPIs still come with risks. In these cases, H2 antagonists are considered the treatment of choice in GERD and other gastric acid diseases.
H2 antagonists differ from H1 antagonists as the latter block the histamine H1 receptors in the body cells that are involved in allergy response.
Side Effects and Adverse Effects of H2 antagonists
The following are the general side effects of H2 antagonists:
- Headache
- Nausea
- Dizziness
The following are adverse effects of H2 antagonists and must be consulted with a healthcare provider:
- Cardiac arrythmias
- Diarrhea (or sometimes constipation)
- Impotence
- Gynecomastia or enlargement of breast tissues in males
- Decreased libido or sexual desire
- Abdominal pain
- Rashes or hives
- Joint pain
- Blurry vision
- Shortness of breath, wheezing, or other breathing problems
- Swelling of extremities
- Difficulty in urination
- Oral or skin dryness
- Insomnia or trouble sleeping
- Hair loss
- Tinnitus or ringing in the ears
- Drowsiness or changes in the level of consciousness
Contraindications and Cautions against H2 antagonists
Aside from previous allergy to any H2 antagonist, any allergies to food dyes, animals, or preservatives should be checked prior to taking an H2 blocker.
Elderly patients may have dizziness and confusion as common side effects of H2 antagonists as compared to younger adults. Many H2 antagonists pass into breastmilk. This can make the nursing baby become increasingly excited and have reduced amounts of stomach acid.
The mother might need to either stop breastfeeding or take an alternative medication during the treatment of her reflux or other acid-related disease.
Currently, there is no research evidence of any contraindication of taking H2 blockers in terms of pregnant women or those who are trying to conceive.
However, it still important for this patient group to check with their doctor before taking any new medication, including H2 antagonist.
H2 antagonists may also affect the absorption of vitamin D, B12, folate, and others vitamins and minerals. The nurse may advise to take the H2 blockers and vitamins at different times of the day as indicated by the physician.
Drug Interactions with H2 antagonists
The following drugs can interact with H2 antagonists:
- Warfarin – some H2 antagonists may reduce the metabolism of the blood thinner called warfarin
- Anticoagulants
- Beta-adrenergic blockers
- Alcohol
- Magnesium supplements
- Some antipsychotics
- Some anti-arrhythmic agents
Nursing Care Plan for Patients on H2 antagonists
Possible Nursing Diagnoses
- Acute Pain related to the H2 antagonists’ side effects on gastrointestinal or central nervous system
- Risk for Injury related to CNS effects
- Decreased cardiac output related to cardiac arrhythmias
- Confusion related to CNS effects (common in elderly patients)
- Deficient Knowledge regarding H2 antagonist therapy
Nursing Assessment
| H2 antagonist Nursing Interventions | Rationales | |
| Check the patient’s diagnosis and how it relates to the administration of H2 antagonists. Assess the patient for signs and symptoms of GI pain, acid reflux or heartburn. Check the patient’s allergy status. Assess for cardiopulmonary status through taking vital signs and ECG if giving IV H2 blockers. | To confirm the indication and safety of administering H2 antagonists. | |
| Conduct a review of current medications and history of alcohol intake. | Alcohol and some medications interact with H2 antagonists. Assess for the current use of Warfarin, anticoagulants, beta-adrenergic blockers, anti-arrhythmic agents, and antipsychoticsAssess if the patient is pregnant and is planning to breastfeed, or if the mother is breastfeeding. | H2 antagonists can be passed into breastmilk which may cause increased excitement due to reduced stomach acid levels in a nursing infant |
| Check for the status of peripheral veins prior to cannulation and administration of intravenous H2 antagonists. If administering oral H2 antagonists, assess for swallowing problems or lesions in the oral mucosa. | To check for any potential problems with administration, hydration, and absorption. To ensure that the right form of H2 antagonists is given through the right route. | |
| Check the patient’s medical history of renal disease or kidney disease. | H2 antagonists should be prescribed with extreme caution in patients with renal disease. Patients with renal impairment are at a higher risk for altered drug metabolism and excretion of H2 antagonists. |
Nursing Planning and Intervention
| H2 antagonist Nursing Interventions | Rationales |
| Administer H2 antagonists through the appropriate route. It is ideal to give it at the same time/s of the day. | To ensure optimal absorption and therapeutic action by H2 antagonists. |
| Educate the patient about the action, indication, common side effects, and adverse reactions to note when taking H2 antagonists. Instruct the patient on how to self-administer oral H2 antagonists. | To inform the patient on the basics of H2 antagonists, as well as to empower him/her to safely self-administer the medication. |
| Advise the patient to avoid operating heavy machinery and driving when starting H2 antagonists. | Patients who are just starting on H2 antagonists should avoid operating heavy machinery and driving due to the potential dizziness, or blurred vision. Once their body has adjusted to the H2 antagonists therapy and the patient feels safe, patient may proceed on their preferred physical activity with caution. |
| Encourage the patient to avoid alcohol intake while taking H2 antagonists. Advise the patient to continue avoiding alcohol consumption after the ulcer has healed. Refer to alcohol support groups as required. | Alcohol may increase stomach acid production. |
| During preparation, gently rotate the vial to mix the product inside and avoid vigorous shaking of the H2 antagonists vial. | To ensure uniform suspension of H2 antagonists inside the vial. |
| Prior to administration, verify the name of the H2 antagonists to be injected with the patient and his/her drug chart. | To promote accuracy and safety in administering the drug. |
| Store H2 antagonist vials or ampules in a cool, dry place, away from direct sunlight. | Following proper storage instructions ensures effectiveness of H2 antagonists therapy. |
| Administer pain medications, assist the patient during ambulation, and provide comfort measures as needed. | To alleviate acid-related symptoms, particularly stomach pain, while providing patient comfort and promoting safety. |
| Reorient the patient regularly. | H2 antagonists may have CNS effects such as confusion especially in elderly patients. Reorienting the patient promotes safety and also allows the nurse to monitor CNS effects of the H2 blocker to the patient. |
Nursing Evaluation
| H2 antagonist Nursing Interventions | Rationales |
| Ask the patient to repeat the information about H2 antagonists. | To evaluate the effectiveness of health teaching on H2 antagonists. |
| Monitor the mental status of the patient. | To ensure that the H2 antagonists did not cause any confusion, or dizziness to the patient. |
| Monitor the patient’s response to H2 antagonists in terms of side effects or adverse effects, particularly diarrhea, gynecomastia, dizziness, tinnitus, and blurry vision. | To check if the current H2 antagonists are effective, or the dose needs to be adjusted, or the drug should be stopped altogether and changed to an alternative treatment. |
| Monitor the patient’s cardiopulmonary, hepatic, and renal status. | To ensure that the patient receives the therapeutic benefit of H2 antagonists therapy and to avoid life-threatening cardiac arrhythmias, as well as to prevent drug toxicity which may lead to hepatic or renal problems. |
Nursing References
Ackley, B. J., Ladwig, G. B., Makic, M. B., Martinez-Kratz, M. R., & Zanotti, M. (2020). Nursing diagnoses handbook: An evidence-based guide to planning care. St. Louis, MO: Elsevier. Buy on Amazon
Gulanick, M., & Myers, J. L. (2022). Nursing care plans: Diagnoses, interventions, & outcomes. St. Louis, MO: Elsevier. Buy on Amazon
Ignatavicius, D. D., Workman, M. L., Rebar, C. R., & Heimgartner, N. M. (2020). Medical-surgical nursing: Concepts for interprofessional collaborative care. St. Louis, MO: Elsevier. Buy on Amazon
Silvestri, L. A. (2020). Saunders comprehensive review for the NCLEX-RN examination. St. Louis, MO: Elsevier. Buy on Amazon
