Description: Famotidine is a histamine H2-receptor blocker that decreases the amount of acid the stomach produces especially at night.

Onset: W/in 1 hr (oral); w/in 30 min (IV).

Duration: 10-12 hr.


Absorption: Readily but incompletely absorbed from the GI tract. Bioavailability: Approx 40-45%. Time to peak plasma concentration: 1-3 hr.

Distribution: Enters the breast milk. Plasma protein binding: Approx 15-20%.

Metabolism: Converted to famotidine S-oxide by hepatic metabolism (small portion).

Excretion: Via urine by active tubular secretion approx 25-30% (oral) and 65-70% (IV) both as unchanged drug. Elimination half-life: Approx 3 hr.

Famotidine is used to treat ulcers of the stomach and intestines and to prevent intestinal ulcers from coming back after they have healed. This medication is also used to treat certain stomach and throat (esophagus) problems (such as erosive esophagitis, gastroesophageal reflux disease-GERD, Zollinger-Ellison syndrome). It works by decreasing the amount of acid your stomach makes. It relieves symptoms such as cough that doesn’t go away, stomach pain, heartburn, and difficulty swallowing. Famotidine belongs to a class of drugs known as H2 blockers.


This form of famotidine is given by vein and is used to treat these conditions for a short time when you cannot take the medication by mouth. Your doctor should switch you to taking this medication by mouth when possible.


How to use famotidine intravenous

There are two methods in giving famotidine, through intravenous route or by vein, and orally or by mouth.

For the intravenous route, the patient is given 20 mg intravenously every 12 hours while admitted in the hospital. The dosage and length of treatment are based on your medical condition and response to treatment. In children, dosage may also be based on body weight.


For the oral route, take 40 mg orally once a day at bedtime  or 20 mg orally twice a day.  Use famotidine exactly as directed on the label, or as prescribed by your doctor. Do not use in larger or smaller amounts or for longer than recommended.

Measure liquid medicine with the dosing syringe provided, or with a special dose-measuring spoon or medicine cup. If you do not have a dose-measuring device, ask your pharmacist for one.

Although most ulcers heal within 4 weeks of famotidine treatment, it may take up to 8 weeks of using this medicine before your ulcer heals. For best results, keep using the medication as directed. Talk with your doctor if your symptoms do not improve after 6 weeks of treatment.


Tell your doctor if your condition persists or worsens.

Pregnancy Risk: Category B (No proven risk in humans)


Side Effects

You should check with your doctor immediately if any of these side effects occur when taking famotidine:


  • Bleeding gums
  • blistering, peeling, or loosening of the skin
  • blood in the urine or stools
  • bloody, black, or tarry stools
  • chest pain
  • chills
  • cough or hoarseness
  • diarrhea
  • fever
  • fever with or without chills
  • general feeling of tiredness or weakness
  • high fever
  • itching
  • joint or muscle pain
  • lower back or side pain
  • painful or difficult urination
  • pale skin
  • pinpoint red spots on the skin
  • red, irritated eyes
  • red skin lesions, often with a purple center
  • shortness of breath
  • sore throat
  • sores, ulcers, or white spots on the lips or in the mouth
  • swollen glands
  • unusual bleeding or bruising
  • unusual tiredness or weakness

Some of the side effects that can occur with famotidine may not need medical attention:

Less common

  • Difficulty having a bowel movement (stool)


Swelling of the breasts or breast soreness in both females and males

Before using this medication, tell your doctor or pharmacist your medical history, especially of: immune system problems, kidney problems, liver problems, lung problems (e.g., asthma, chronic obstructive pulmonary disease-COPD), other stomach problems (e.g., tumors).


Some symptoms may actually be signs of a more serious condition. Get medical help right away if you have: heartburn with lightheadedness/sweating/dizziness, chest/jaw/arm/shoulder pain (especially with shortness of breath, unusual sweating), unexplained weight loss.


Older adults may be more sensitive to the side effects of this drug, especially confusion.




Some products need stomach acid so that the body can absorb them properly. Famotidine decreases stomach acid, so it may change how well these products work. Some affected products include atazanavir, dasatinib, delavirdine, certain azole antifungals (such as itraconazole, ketoconazole), pazopanib, among others.


Do not take this medication with other products that contain famotidine or other H2 blockers (cimetidine, nizatidine, ranitidine).

If overdose is suspected, contact a poison control center or emergency room immediately.




Do not share this medication with others.


Lifestyle changes such as stress reduction programs, stopping smoking, limiting alcohol, and diet changes (such as avoiding caffeine and certain spices) may help this medication work better. Talk to your doctor or pharmacist about lifestyle changes that might benefit you.


Laboratory and/or medical tests (e.g., endoscopy, kidney function tests) may be performed to monitor your progress or check for side effects. Consult your doctor for more details.


Missed Dose

For the best possible benefit, it is important to receive each scheduled dose of this medication as directed. If you miss a dose, contact your doctor or pharmacist right away to establish a new dosing schedule. Do not double the dose to catch up.



Consult the product instructions and your pharmacist for storage details. Keep all medications away from children and pets.


Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company.




Available Brands

H2Bloc [ Westmont ] Hista-Bloc Injection [ Standard Chem ]


Also marketed as

Acrilo [ Pasteur Pharma ] Famorila [ Glenmark ]
H2 BLOC Tab/Amp [ Biomedis ] International Apex Famotidine [ Mustafa ]
Modin [ Shanxi Taisheng ] Motid [ Randril ]
Pepcidine [ Merck Sharp & Dohme ] Ulcefam [ Unison ]

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