Famotidine: An h3 Blocker That Relieves Heartburn Fast

Famotidine is an ingredient found in medications that prevent and lessen heartburn symptoms. When you take famotidine, your stomach makes less acid, which helps stop heartburn from occurring.

What Is Famotidine Used For?

Stomach acid contains enzymes and other molecules that help digest food¹. However, when too much acid is produced, it can damage the stomach or other digestive organs, leading to several conditions.

Famotidine, when prescribed by a doctor, can be used to treat²:

Acid reflux is a condition that occurs when stomach acid and undigested food flow back out of your stomach and into your esophagus, the tube that connects your mouth and stomach. When acid reflux happens regularly, it is called GERD. Heartburn is a symptom of acid reflux. It is characterized by a burning sensation in the chest.

Non-prescription famotidine can be used to:

How Does Famotidine Work?

Stomach acid is made by parietal cells, a type of cell found in the lining of the stomach. These cells contain several “switches” that help control when acid production is turned on or off. One switch is a protein called the h3 histamine receptor. When this protein is activated, parietal cells begin making more acid³.

Famotidine is a type of drug known as an h3 receptor antagonist (h3RA) or simply an h3 blocker. h3 blockers attach to the h3 histamine receptor, preventing it from turning on and blocking the parietal cells from creating extra acid³. Less acid in the stomach reduces the chances that acid reflux will occur.

Watch a video to see how h3 blockers like PEPCID^® work:

How To Take Over-The-Counter

Famotidine Tablets

In order to treat acid reflux symptoms like heartburn, adults and children 12 years or over can take a 20 mg tablet of famotidine once or twice per day. You can take famotidine tablets when you start to feel heartburn symptoms come on. Alternatively, to prevent heartburn, you can take one tablet 10 to 60 minutes before eating or drinking something that could trigger heartburn⁴.

Simply swallow the tablet with a full glass of water. Do not chew the tablet. For children under the age of 12, ask a doctor before using famotidine⁴.

Don’t use more than two famotidine tablets within a 24-hour period. Additionally, stop use and see a doctor if you need to take this product for more than two weeks².

If you have any questions about using famotidine tablets, ask your doctor or pharmacist.

When you need heartburn relief fast, try Maximum Strength PEPCID AC^® with 20 mg of famotidine. You can also take Maximum Strength PEPCID AC^® before a meal in order to help prevent symptoms from starting in the first place.

Maximum Strength PEPCID AC^® is not indicated to treat GERD. If you have been experiencing hearburn for three months, talk to your doctor before using Maxium Strength PEPCID AC^®. If you have trouble or pain swallowing food, vomiting with blood, or bloody or black stools, do not use Maximum Strength PEPCID AC^®, and see your doctor right away. These may be signs of a more serious condition.

Precautions & Side Effects

Famotidine side effects can include²:

Tell your doctor if you experience these side effects and they don’t go away. Additionally, call your doctor right away if you notice itching, swelling, hives or a rash, hoarseness, or breathing or swallowing problems².

Don’t use this medication if you have an allergy to famotidine or other acid-reducing drugs. Additionally, you should avoid taking famotidine at the same time as other heartburn medications unless your doctor recommends it. Tell your doctor about all prescription medications, over-the-counter drugs, and supplements that you are taking, since famotidine can sometimes interact with them.

References

• ¹How Does the Stomach Work? InformedHealth.org.
  Updated August 21, 2016. Accessed December 16, 2021.
• ²Famotidine. MedlinePlus. Revised October 15, 2017.
  Accessed December 16, 2021.
• ³Engevik AC, Kaji I, Goldenring JR. The Physiology of the
  Gastric Parietal Cell. Physiol Rev. 2020;100(2):573-602.
• ⁴Label: Pepcid AC Maximum Strength – Famotidine Tablet,
  Film Coated. DailyMed. Updated October 13, 2021. Accessed December 16, 2021.

Famotidine – StatPearls – NCBI Bookshelf

Kim Nguyen; Graham D. Dersnah; Rajni Ahlawat.

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Last Update: July 11, 2022.

Continuing Education Activity

Famotidine decreases the production of stomach acid, and its pharmacologic activity is used in the treatment of acid-related gastrointestinal conditions. Famotidine is available both by prescription and over-the-counter (OTC). It is FDA approved and available through prescription for the treatment of duodenal ulcer, gastric ulcer, and gastroesophageal reflux disease (GERD) in adults and children, with a further indication for treatment of pathological hypersecretory conditions in adults. Famotidine is also FDA approved for over-the-counter treatment and prevention of heartburn due to gastroesophageal reflux in adults and pediatrics. It also has off-label uses. This activity outlines the indications, mechanism of action, methods of administration, important adverse effects, contraindications, monitoring, and toxicity of famotidine, so providers can direct patient therapy as needed to achieve positive outcomes.

Objectives:

• Identify the mechanism of action of famotidine.

• Discuss the approved and off label indications for famotidine.

• Recall the contraindications and adverse event profile of famotidine.

• Explain interprofessional team strategies for improving care coordination and communication to advance famotidine therapy and improve outcomes.

Access free multiple choice questions on this topic.

Indications

Famotidine decreases the production of stomach acid, and its pharmacologic activity is used in the treatment of acid-related gastrointestinal conditions. [1][2] Famotidine is available both by prescription and over-the-counter (OTC). It is US Food and Drug Administration (FDA) approved and available through prescription for the treatment of duodenal ulcer, gastric ulcer, and gastroesophageal reflux disease (GERD) in adults and children, with a further indication for treatment of pathological hypersecretory conditions in adults.[3] Famotidine is also FDA approved for over-the-counter treatment and prevention of heartburn due to gastroesophageal reflux in adults and pediatrics.[4] Famotidine is used off-label for reducing gastrointestinal risks of NSAIDs.[5] It is also used off-label for the treatment of refractory urticarial, prevention of stress ulcer in critically-ill patients and symptomatic relief of gastritis.[6]

Mechanism of Action

Famotidine is a competitive histamine H-receptor antagonist (h3RA) that binds to the H-receptors located on the basolateral membrane of the parietal cell in the stomach, effectively blocking histamine actions. Its pharmacologic activity results in the inhibition of gastric secretion by suppressing acid concentration and volume of gastric secretion. Famotidine inhibits both basal and nocturnal gastric acid secretion as well as reduces gastric volume, acidity, and secretion stimulated by food, caffeine, insulin, and pentagastrin.[7][8][9]

Administration

Per famotidine’s package insert, it is available in intravenous (IV) solution, oral suspension, and tablet formulations (10 mg, 20 mg, and 40 mg). The intravenous solution can be administered as an IV push over at least two minutes and as an IV infusion over 15 to 30 minutes. Over-the-counter formulations are available in gel capsules, tablets, and chewable tablets of 10 mg or 20 mg. The oral tablet is administered without regard to meals. The suspension formulation should be shaken vigorously before use. The over-the-counter tablet should not be chewed, and the dose may be taken 10 to 60 minutes before consuming food or drinks known to cause heartburn. Patients should not take over-the-counter famotidine for more than 2 weeks unless directed by their health care provider. Famotidine is metabolized by the hepatic cytochrome P450 enzymes, but it has a minimal inhibitory impact on other drugs metabolism.[10] Per package insert, the following medications should not be used concurrently with famotidine: cefuroxime, dasatinib, delavirdine, neratinib, pazopanib, and risedronate.

Adverse Effects

The adverse effects of the intravenous formulation occur locally as it may irritate the injection site; however, the frequency has not been defined. Most common adverse effects include agitation (infants equal to 14%; adults less than 1%), headache (5%), dizziness (1%), diarrhea (2%), and constipation (1%). Due to central nervous system (CNS) adverse effects, longer dosing intervals or reduced doses may be used instead to adjust for the resulting longer elimination half-life of famotidine.[10][11][12] An increased risk of developing community-acquired pneumonia and acute gastroenteritis have been linked to the use of famotidine as well as other gastric acid inhibitors in the pediatric population. [13] Patients who use over-the-counter famotidine must notify their health care provider if they experience frequent chest pain, frequent wheezing particularly with heartburn, unexplained weight loss, stomach pain, heartburn more than 3 months, heartburn with lightheadedness, sweating, or dizziness. Over-the-counter famotidine must be discontinued if a patient’s heartburn continues and/or worsens, or if they use it for more than 14 days.[14]

Contraindications

Famotidine is contraindicated for use by patients with serious hypersensitivity to famotidine itself or any component of the formulation. Cross-sensitivity of h3RAs has been observed; therefore, famotidine should not be administered to patients with a history of hypersensitivity to cimetidine. In addition, the over-the-counter tablets should not be used if the patient has trouble and/or pain when swallowing food, vomiting with blood, or bloody or black stools. The over-the-counter tablets should also not be used by patients who are allergic to other acid reducers, have renal impairment, or are currently taking other acid reducers.

Monitoring

Famotidine is substantially excreted by the kidney; thus, it may be useful for healthcare professionals to monitor renal function especially in elderly patients. A patient’s complete blood count (CBC), gastric pH and occult blood in patients with gastrointestinal (GI) bleeding should be monitored.

Toxicity

As famotidine is excreted mainly by the kidney, the risk of toxic reactions may be greater in patients with impaired renal function. Dose adjustment in patients who have moderate to severe renal impairment is necessary.[11][12] Per famotidine’s package insert, oral doses outside of FDA-approved doses of up to 640 mg per day have been given to adult patients with pathological hypersecretory states with no serious adverse outcomes. Cases of overdose are similar to those encountered in normal clinical experience. Treatment of an overdose should include removing unabsorbed medications from the gastrointestinal tract, the patient should be monitored accordingly, and supportive therapy provided. Famotidine is classified as pregnancy category B and should be used during pregnancy only if needed. Famotidine is present in breast milk, and the decision for a mother to breastfeed during therapy should be based on the balance of risk to the infants and treatment benefits to the mother. Compared to other h3RAs, famotidine exhibit one of the lowest concentrations in break milk and is thus, maybe one of the preferred agents in this setting.[15][16]

Enhancing Healthcare Team Outcomes

The American Society of Health-System Pharmacists (ASHP) in 1999 released a guideline focusing on the prevention of stress ulcer in medical, surgical, respiratory, and pediatric intensive care unit (ICU) patients. Since then, and in recent years, the use of stress ulcer prophylaxis in a non-ICU setting, particularly in the general medical setting, have increased despite little to no evidence supporting its use. The use of acid-suppressive therapy (AST) is overused in hospital patients, with as many as 71% of patient’s receiving treatment without an appropriate indication in the general medicine ward. Furthermore, a significant number of patients continue on acid-suppressive therapy when discharged from the hospital which can lead to increased medical cost and the risk of adverse drug reactions for patients. Health care professionals play an important role in enhancing patient’s safety by minimizing the inappropriate use of AST. Physicians should carefully consider the need for AST in patients in the general medicine ward and pharmacist can communicate with physicians and ask about the unnecessary use of acid-suppressive therapy. Education about the proper use of acid-suppressive therapy in ICU settings per ASHP recommendations will help reduce its inappropriate use significantly.[17][18][19]

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References

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Hudson N, Taha AS, Russell RI, Trye P, Cottrell J, Mann SG, Swanell AJ, Sturrock RD, Hawkey CJ. Famotidine for healing and maintenance in nonsteroidal anti-inflammatory drug-associated gastroduodenal ulceration. Gastroenterology. 1997 Jun;112(6):1817-22. [PubMed: 9178671]

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Inalöz SS, Goral V, Sari I, Canberk Y, Ulak G. Omeprazole, nitrendipine, famotidine and stress-induced ulcers. Acta Gastroenterol Belg. 1997 Jul-Sep;60(3):192-6. [PubMed: 9396173]

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Poluzzi E, Raschi E, Moretti U, De Ponti F. Drug-induced torsades de pointes: data mining of the public version of the FDA Adverse Event Reporting System (AERS). Pharmacoepidemiol Drug Saf. 2009 Jun;18(6):512-8. [PubMed: 19358226]

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Lin JH, Chremos AN, Yeh KC, Antonello J, Hessey GA. Effects of age and chronic renal failure on the urinary excretion kinetics of famotidine in man. Eur J Clin Pharmacol. 1988;34(1):41-6. [PubMed: 2896129]

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Canani RB, Cirillo P, Roggero P, Romano C, Malamisura B, Terrin G, Passariello A, Manguso F, Morelli L, Guarino A., Working Group on Intestinal Infections of the Italian Society of Pediatric Gastroenterology, Hepatology and Nutrition (SIGENP). Therapy with gastric acidity inhibitors increases the risk of acute gastroenteritis and community-acquired pneumonia in children. Pediatrics. 2006 May;117(5):e817-20. [PubMed: 16651285]

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McRorie JW, Kirby JA, Miner PB. Histamine2-receptor antagonists: Rapid development of tachyphylaxis with repeat dosing. World J Gastrointest Pharmacol Ther. 2014 May 06;5(2):57-62. [PMC free article: PMC4023325] [PubMed: 24868486]

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Richter JE. Review article: the management of heartburn in pregnancy. Aliment Pharmacol Ther. 2005 Nov 01;22(9):749-57. [PubMed: 16225482]

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Garbis H, Elefant E, Diav-Citrin O, Mastroiacovo P, Schaefer C, Vial T, Clementi M, Valti E, McElhatton P, Smorlesi C, Rodriguez EP, Robert-Gnansia E, Merlob P, Peiker G, Pexieder T, Schueler L, Ritvanen A, Mathieu-Nolf M. Pregnancy outcome after exposure to ranitidine and other h3-blockers. A collaborative study of the European Network of Teratology Information Services. Reprod Toxicol. 2005 Mar-Apr;19(4):453-8. [PubMed: 15749258]

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Farrell CP, Mercogliano G, Kuntz CL. Overuse of stress ulcer prophylaxis in the critical care setting and beyond.