Famotidine; Uses, Dosage, Side effects, Drug Interactions

Last updated: February 7, 2026Reviewed date: February 7, 2026Reading time: 7 min read
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Famotidine is a propanimidamide and histamine H2-receptor antagonist with antacid activity. As a competitive inhibitor of histamine H2-receptors located on the basolateral membrane of the parietal cell, famotidine reduces basal and nocturnal gastric acid secretion, resulting in a reduction in gastric volume, acidity, and amount of gastric acid released in response to various stimuli....

For severe symptoms, danger signs, pregnancy, child illness, or sudden worsening, seek urgent medical care.

বাংলা রোগী নোট এখনো যোগ করা হয়নি। পোস্ট এডিটরে “RX Bangla Patient Mode” বক্স থেকে সহজ বাংলা সারাংশ যোগ করুন।

এই তথ্য শিক্ষা ও সচেতনতার জন্য। এটি ডাক্তারি পরীক্ষা, রোগ নির্ণয় বা প্রেসক্রিপশনের বিকল্প নয়।

Article Summary

Famotidine is a propanimidamide and histamine H2-receptor antagonist with antacid activity. As a competitive inhibitor of histamine H2-receptors located on the basolateral membrane of the parietal cell, famotidine reduces basal and nocturnal gastric acid secretion, resulting in a reduction in gastric volume, acidity, and amount of gastric acid released in response to various stimuli. Famotidine is a histamine H2 receptor antagonist that inhibits stomach acid production. It is a competitive histamine H2-receptor antagonist. Its main pharmacodynamic effect is the inhibition...

Key Takeaways

  • This article explains Mechanism of Action of Famotidine in simple medical language.
  • This article explains Indications of  Famotidine in simple medical language.
  • This article explains Contra-Indications of Famotidine in simple medical language.
  • This article explains Dosage of Famotidine in simple medical language.
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Emergency safety firstUrgent warning signs are highlighted below.

Seek urgent medical care if you notice

These warning signs are general safety guidance. Local emergency numbers and clinical judgment should always come first.

  • Severe symptoms, breathing difficulty, fainting, confusion, or rapidly worsening illness.
  • New weakness, severe pain, high fever, or symptoms after a serious injury.
  • Any symptom that feels urgent, unusual, or unsafe for the patient.
1

Emergency now

Use emergency care for severe, sudden, rapidly worsening, or life-threatening symptoms.

2

See a doctor

Book a professional medical evaluation if symptoms persist, worsen, recur often, affect daily activities, or occur in a high-risk patient.

3

Learn safely

Use this article to understand possible causes, tests, treatment options, prevention, and questions to ask your clinician.

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Definition

Famotidine is a histamine H2 receptor antagonist that inhibits stomach acid production. It is a competitive histamine H2-receptor antagonist. Its main pharmacodynamic effect is the inhibition of gastric secretion. It is commonly used in the treatment of peptic ulcer disease and gastroesophageal reflux disease. Unlike cimetidine, the first H2 antagonist, famotidine has no effect on the cytochrome P450 enzyme system and does not appear to interact with other drugs.

Mechanism of Action of Famotidine

Famotidine binds competitively to H2-receptors located on the basolateral membrane of the parietal cell, blocking histamine effects. This competitive inhibition results in reduced basal and nocturnal gastric acid secretion and a reduction in gastric volume, acidity, and amount of gastric acid released in response to stimuli including food, caffeine, insulin, betazole, or pentagastrin.

Famotidine binds competitively to H2-receptors located on the basolateral membrane of the parietal cell, blocking histamine effects. This competitive inhibition results in reduced basal and nocturnal gastric acid secretion and a reduction in gastric volume, acidity, and amount of gastric acid released in response to stimuli including food, caffeine, H2-receptor antagonists inhibit basal and nocturnal gastric acid secretion by competitive inhibition of the action of histamine at the histamine H2-receptors of the parietal cells. They also inhibit gastric acid secretion stimulated by food, betazole, pentagastrin, caffeine, insulin, and physiological vagal reflex. /Histamine H2-receptor antagonists/

Indications of  Famotidine

Contra-Indications of Famotidine

Dosage of Famotidine

Strengths: 10 mg, 20 mg; 40 mg; 20 mg/50 mL; 40 mg/5 mL; 10 mg/mL;  20 mg/10 mL

Gastroesophageal Reflux Disease

Oral

  • Usual dose: 20 mg orally 2 times day
  • Duration of therapy: Up to 6 weeks

Parenteral

  • Usual dose: 20 mg IV every 12 hours

Duodenal Ulcer

Oral

  • Usual dose: 40 mg orally once a day at bedtime OR 20 mg orally 2 times a day
  • Maintenance dose: 20 mg orally once a day at bedtime
  • Duration of therapy: 4 weeks

Parenteral

  • Usual dose: 20 mg IV every 12 hours

Peptic Ulcer

Oral

  • Usual dose: 40 mg orally once a day at bedtime OR 20 mg orally 2 times a day
  • Maintenance dose: 20 mg orally once a day at bedtime
  • Duration of therapy: 4 weeks

Parenteral

  • Usual dose: 20 mg IV every 12 hours

Zollinger-Ellison Syndrome

Oral

  • Initial dose: 20 mg orally every 6 hours
  • Maximum dose: 160 mg orally every 6 hours

Parenteral

  • Usual dose: 20 mg IV every 6 to 12 hours

Dyspepsia

Oral, Over-the-Counter (OTC) Formulations

  • Treatment dose: 10 to 20 mg orally once
  • Symptom prevention: 10 to 20 mg orally once 10 to 60 minutes prior to consuming food/beverages that cause heartburn
  • Maximum dose: 2 tablets/day
  • The maximum duration of therapy: 14 days

Pediatric Peptic Ulcer

1 TO 16 years, Oral

  • Usual dose: 0.5 mg/kg orally once a day at bedtime OR 0.25 mg/kg orally 2 times a day
  • Maximum dose: 40 mg/day

Parenteral

  • Initial dose: 0.25 mg/kg IV injected over at least 2 minutes OR infused over 15 minutes every 12 hours
  • Maximum dose: 40 mg/day

16 years & older, Oral

  • Usual dose: 40 mg orally once a day at bedtime OR 20 mg orally 2 times a day
  • Maintenance dose: 20 mg orally once a day at bedtime
  • Duration of therapy: 4 weeks

Parenteral

  • Usual dose: 20 mg IV every 12 hours

Gastroesophageal Reflux Disease

Less than 3 months, Oral

  • Initial dose: 0.5 mg/kg orally once a day
  • Duration of therapy: Up to 8 weeks

3 month to less than 1 year, Oral

  • Initial dose: 0.5 mg/kg orally 2 times a day
  • Duration of therapy: Up to 8 weeks

1 Year to 16 Years, Oral

  • Usual dose: 0.5 mg/kg/day orally 2 times a day
  • Maximum dose: Up to 40 mg/dose

Parenteral

  • Initial dose: 0.25 mg/kg IV injected over at least 2 minutes OR infused over 15 minutes every 12 hours
  • Maximum dose: 40 mg/day

16 YEARS AND OLDER Oral

  • Usual dose: 20 mg orally 2 times day
  • Duration of therapy: Up to 6 weeks

Parenteral

  • Usual dose: 20 mg IV every 12 hours

Side Effects of Famotidine

The most common

More common

Rare

Drug Interactions

Famotidine may interact with following drugs, supplements, & may change the efficacy of drug

Pregnancy Catagory

FDA Pregnancy Category B

Pregnancy

The safety of this medication for use during pregnancy has not been established. This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.

Lactation

You should not take famotidine if you are breastfeeding. It may be excreted in your breast milk and may harm your nursing child.

References

Famotidine; Uses, Dosage, Side effects, Drug Interactions

Doctor visit helper

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A simple rural-patient checklist to help you explain symptoms clearly, ask better questions, and avoid unsafe self-treatment.

Safety note: This is not a prescription or diagnosis. For severe symptoms, pregnancy danger signs, children with serious illness, chest pain, breathing difficulty, stroke-like weakness, or major injury, seek urgent care.

Which doctor may help?

Start with a registered doctor or the nearest qualified health center.

What to tell the doctor

  • Write when the problem started and how it changed.
  • Bring old prescriptions, investigation reports, and current medicines.
  • Write allergies, pregnancy status, diabetes, kidney/liver disease, and major past illnesses.
  • Bring one family member if the patient is weak, elderly, confused, or a child.

Questions to ask

  • What is the most likely cause of my symptoms?
  • Which danger signs mean I should go to hospital quickly?
  • Which tests are necessary now, and which can wait?
  • How should I take medicines safely and what side effects should I watch for?
  • When should I come for follow-up?

Tests to discuss

  • Vital signs: temperature, pulse, blood pressure, oxygen saturation
  • Basic physical examination by a clinician
  • CBC, urine test, blood sugar, or imaging only when clinically needed

Avoid these mistakes

  • Do not use antibiotics, steroid tablets/injections, or strong painkillers without proper medical advice.
  • Do not hide pregnancy, kidney disease, ulcer, allergy, or blood thinner use.
  • Do not delay emergency care when danger signs are present.

Medicine safety and first-aid guide

This section is for patient education only. It does not replace a doctor, pharmacist, or emergency care.

Safe first steps

  • Avoid heavy lifting, sudden bending, and prolonged bed rest.
  • Use comfortable posture and gentle movement as tolerated.
  • Discuss physiotherapy, X-ray, or MRI only when clinically needed.

OTC medicine safety

  • For mild back pain, pain-relief medicine may be discussed with a doctor or pharmacist.
  • Avoid repeated painkiller use if you have kidney disease, stomach ulcer, uncontrolled blood pressure, or are taking blood thinners.

Avoid these mistakes

  • Do not start antibiotics without a proper medical decision.
  • Do not use steroid tablets or injections casually for quick relief.
  • Do not delay emergency care because of home remedies.

Get urgent help if

  • Back pain with leg weakness, numbness around private area, loss of urine/stool control, fever, cancer history, or major injury needs urgent care.
Medicine names, dose, and timing must be decided by a qualified clinician or pharmacist after checking age, pregnancy, allergy, other diseases, and current medicines.

For rural patients and family caregivers

Patient health record and symptom diary

Write your symptoms, medicines already taken, test results, and questions before visiting a doctor. This note stays on your device unless you print or copy it.

Doctor to discuss: Orthopedic / spine specialist, physical medicine doctor, or qualified clinician
Tests to discuss with doctor
  • Neurological examination for leg power, sensation, reflexes, and straight leg raise
  • X-ray only if injury, deformity, long-lasting pain, or doctor suspects bone problem
  • MRI discussion if severe nerve symptoms, weakness, bladder/bowel problem, or persistent symptoms
Questions to ask
  • What is the most likely cause of my symptoms?
  • Which warning signs mean I should go to emergency care?
  • Which tests are really needed now?
  • Which medicines are safe for my age, pregnancy status, allergy, kidney/liver/stomach condition, and current medicines?
  • Is physiotherapy, posture correction, or activity modification needed?

Emergency warning signs such as chest pain, severe breathing difficulty, sudden weakness, confusion, severe dehydration, major injury, or loss of bladder/bowel control need urgent medical care. Do not wait for online information.

Safe pathway to proper treatment

Care roadmap for: Famotidine; Uses, Dosage, Side effects, Drug Interactions

Use this simple roadmap to understand the next safe steps. It is educational and does not replace examination by a doctor.

Go to emergency care if you notice:
  • Severe or rapidly worsening symptoms
  • Breathing difficulty, chest pain, fainting, confusion, severe weakness, major injury, or severe dehydration
Doctor / service to discuss: Qualified healthcare provider; specialist depends on symptoms and examination.
  1. Step 1

    Check danger signs first

    If danger signs are present, seek emergency care and do not wait for online information.

  2. Step 2

    Record the symptom story

    Write when symptoms started, severity, medicines already taken, allergies, pregnancy status, and test results.

  3. Step 3

    Visit a qualified clinician

    A doctor, nurse, or qualified healthcare provider can examine you and decide which tests or treatment are needed.

  4. Step 4

    Do only useful tests

    Do tests after clinical assessment. Avoid unnecessary tests, random antibiotics, or repeated medicines without diagnosis.

  5. Step 5

    Follow up and return early if worse

    If symptoms worsen, new warning signs appear, or treatment is not helping, return for review quickly.

Rural patient practical tips
  • Take a written symptom diary and all previous prescriptions/test reports.
  • Do not hide medicines already taken, even herbal or over-the-counter medicines.
  • Ask which warning signs mean urgent referral to hospital.

This roadmap is for education. A real diagnosis and treatment plan requires history, examination, and clinical judgment.

RX Patient Help

Ask a health question safely

Write your symptom story. A health professional or site editor can review it before any answer is prepared. This box is not for emergency care.

Emergency first: Severe chest pain, breathing trouble, unconsciousness, stroke signs, severe injury, heavy bleeding, or rapidly worsening symptoms need urgent local medical care now.

Frequently Asked Questions

Is this article a replacement for a doctor?

No. It is educational content only. Patients should consult a qualified clinician for diagnosis and treatment.

When should I seek urgent care?

Seek urgent care for severe symptoms, rapidly worsening condition, breathing difficulty, severe pain, neurological changes, or any emergency warning sign.

References

Add references, clinical guidelines, textbooks, journal articles, or trusted medical sources here. You can edit this area from the RX Article Professional Blocks panel.

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