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Famotidine dosage, forms, and strengths

Medically reviewed by Jesse P. Houghton, MD, FACG
Fellow of the American College of Gastroenterology
Written by Georgia C. Yalanis, MD
Medical Doctor
Updated Jan 4, 2024  •  Published Jan 27, 2022
Fact Checked

Famotidine is a histamine type 2 receptor antagonist, also known as an H-2 blocker. H-2 blockers decrease the amount of acid produced by the stomach. They are often used in the treatment of conditions in the stomach and esophagus including heartburn, indigestion, stomach ulcers, gastroesophageal reflux disease (GERD), and other pathologic hypersecretory conditions. 

Famotidine is technically neither an antacid nor a proton pump inhibitor. This medication is available in several formulations and is manufactured under several brand names, some of which are available over the counter (OTC) and some of which are prescription drugs dosed by a healthcare professional. 

Note: Prior to April 2020, Zantac preparations used to be formulated with ranitidine (Zantac 75, Zantac 150). These formulations were recalled due to the presence of a potentially carcinogenic contaminant called N-nitrosodimethylamine (NDMA). Currently, all Zantac formulations are made with famotidine (Zantac 360, Zantac 360 Max) and are safe for use. Any Zantac medications or ranitidine prescriptions filled prior to April 2020 should not be taken and should be appropriately discarded. More information about this recall and how to safely discard medication can be found here. 

RELATED: Get famotidine coupons | What is famotidine?

Famotidine forms and strengths

Famotidine is available in the following forms and strengths.

  • Tablets: 10 mg, 20 mg, 40 mg

  • Oral suspension: 40 mg per 5 ml

  • Intravenous injection solution: 10 mg/1 ml, 20 mg/50 ml 

  • Oral suspension: 40 mg/5ml

Famotidine dosage for adults

The Food and Drug Administration (FDA) has approved famotidine for adult and pediatric patients who weigh more than 40 kg and who have active duodenal ulcers, active gastric ulcers, symptomatic non-erosive gastroesophageal reflux disease, and erosive esophagitis due to GERD. These conditions are usually diagnosed by an upper endoscopy. Famotidine is also approved for adults for the treatment of pathological hypersecretory conditions such as Zollinger-Ellison syndrome and multiple endocrine neoplasia (MEN) syndrome, as well as the reduction of the risk of duodenal ulcer recurrence.

Famotidine is sometimes used off-label in the treatment of:

  • NSAID-associated gastrointestinal complications

  • Acute and chronic urticaria 

  • Symptomatic relief of gastritis

  • Prophylaxis for stress gastritis in intubated or critically-ill patients

  • Acid aspiration prophylaxis prior to anesthesia

The following dosage table will include typical dosages for the most common uses of famotidine.

Famotidine dosage chart
Indication Starting dosage Standard dosage Maximum dosage
Self-administration for heartburn, acid indigestion, or sour stomach 10 mg tablet taken 10-60 minutes before eating  10-20 mg tablet taken 10-60 minutes before eating  40 mg per day 
Duodenal ulcer, active 40 mg tablet taken at bedtime for 4-8 weeks, or 20 mg tablet taken twice per day, or 20 mg IV infusion every 12 hours if unable to take medication by mouth  40 mg tablet taken at bedtime for 4-8 weeks, or 20 mg tablet taken twice per day, or 20 mg IV infusion every 12 hours if unable to take medication by mouth  40 mg twice per day
Duodenal ulcer, maintenance treatment 20 mg tablet taken at bedtime  20 mg tablet taken at bedtime  40 mg per day 
Intractable ulcers 20 mg IV twice per day 20 mg IV twice per day 20 mg IV twice per day
GERD 20 mg tablet taken twice per day  20 mg tablet taken twice per day  40 mg twice per day 
GERD with erosive esophagitis  20 mg tablet taken twice per day  20-40 mg tablet taken twice per day  80 mg per day 
Hypersecretory conditions  20 mg tablet taken four times per day, or 20 mg IV twice per day 20-60 mg tablet taken four times per day, or 20 mg IV twice per day 160 mg four times per day 
NSAID-induced ulcer prophylaxis  40 mg tablet taken twice per day  40 mg tablet taken twice per day  80 mg per day 

Famotidine dosage for OTC use

Famotidine preparations are available over the counter for self-administration. These preparations have been shown to be very effective in aborting and preventing pain and discomfort associated with heartburn, upset stomach, and acid indigestion. 

OTC dosage forms are available in 10 mg chewable tablets with antacids as well as 10 to 20 mg tablets that must be swallowed whole. 

These medications are generally safe and well-tolerated, however if symptoms worsen, are not relieved shortly after taking this medication, or do not go away after several weeks, it is important to speak with a healthcare provider as something more serious may be going on. 

Famotidine dosage for duodenal ulcers

Oversecretion of stomach acid, non-steroidal anti-inflammatory drugs (NSAIDs), and a bacteria in the stomach called Helicobacter pylori can all cause ulcers to form in the body of the stomach and the closest portion of the intestines to the stomach, known as the duodenum. Ulceration can be painful and lead to other complications. Famotidine is used in the treatment of active duodenal ulcers as well as in maintenance treatment after the ulcer(s) has been healed. 

For active duodenal ulcers, famotidine is given as a 40 mg dose, usually taken at bedtime, although it is also commonly prescribed twice daily for this indication.

For duodenal ulcer maintenance treatment, famotidine is given as a 20 mg dose, taken at bedtime. 

For difficult to heal ulcers, famotidine is given in a 20 mg IV infusion, twice per day, usually in hospitalized patients.

Famotidine dosage for GERD

Gastroesophageal reflux disease is a chronic condition that occurs when excess stomach acid is “refluxed” up into the esophagus. Excess gastric acid is very caustic and can cause erosion of the epithelial tissue in the esophagus. This results in a painful “burning” sensation that is commonly referred to as “heartburn.” Acid reflux and heartburn that occurs more than two times per week may be diagnosed as GERD. 

In the management of GERD, famotidine is typically dosed as a 20 mg tablet taken twice per day. In more refractory cases, it is sometimes prescribed at the higher 40 mg dose.

For GERD with evidence of erosive esophagitis, famotidine is typically dosed at 20 to 40 mg, in tablet form taken twice per day. 

Famotidine dosage for hypersecretory conditions 

There are several conditions where parietal cells, the cells in the stomach responsible for gastric acid secretion, produce more stomach acid than is physiologically needed. This inappropriate secretion usually occurs via a gastrin-producing tumor in Zollinger-Ellison syndrome or a condition called multiple endocrine neoplasia type 1 (MEN-1). The latter is also associated with parathyroid tumors which cause increases in serum calcium concentrations that may stimulate gastric acid hypersecretion. 

For hypersecretory conditions, a typical dose of famotidine is 20-60 mg tablets taken four times per day, however doses can be increased significantly under a doctor’s supervision. 

Famotidine dosage for NSAID-induced ulcers

Non-steroidal anti-inflammatory drugs inhibit the enzyme COX-1, which releases prostaglandins that protect the gastric mucosa from stomach acid. Chronic use of NSAIDs can cause ulcers by stomach acid damaging the gastrointestinal mucosa. This is a very common condition associated with overuse of NSAIDs, and therefore it is important to assess an individual’s gastrointestinal risk factors before prescribing NSAIDs for long-term use. 

For NSAID-induced ulcers, famotidine is given as a 40 mg tablet taken twice per day. 

Famotidine dosage for children

Famotidine is available for use in children as young as infants in tablet form or as an oral suspension. Similar to adult patients, it is typically used in the management of peptic ulcer disease and GERD, with standard dosages based upon age and the condition it is being used to treat.

Famotidine dosage by weight/age
Indication Age Recommended dosage (tablet) Recommended dosage (liquid)
Peptic ulcer disease (duodenal ulcer or gastric ulcer) All weights, ages 1-16 years old  0.5-1.0 mg/kd/day taken once or twice per day for 8 weeks 0.5-1.0 mg/kd/day taken once or twice per day for 8 weeks
GERD <3 months old 0.5-1 mg/kg/dose once per day for 4-8 weeks  0.5-1 mg/kg/dose once per day for 4-8 weeks 
3-12 months old  1-2 mg/kg/day divided into two doses per day for 4-8 weeks 1-2 mg/kg/day divided into two doses per day for 4-8 weeks
1-16 years of age 1 mg/kg/day divided into two doses for 6-12 weeks 1 mg/kg/day divided into two doses for 6-12 weeks

Famotidine dosage restrictions

Renal dosing 

Famotidine is substantially excreted by the kidneys, thus the risk of toxic side effects of famotidine may be increased in individuals with kidney disease or in older adults. In certain populations, and in an inpatient setting, healthcare providers should monitor renal function when giving infusions of this medication. Likewise, renal dose adjustments should be made when considering dosages for this medication in adults and children with renal impairment. There are specific dose adjustments for each condition and for each administration type. 

Drugs that require gastric pH for absorption

There are certain medications that require an acidic environment in the stomach in order to be absorbed properly. When these medications are administered with famotidine, they may not be absorbed completely, causing loss of efficacy and therapeutic benefit. It is important to disclose all medications you are taking with your healthcare provider prior to beginning therapy with famotidine. 

Examples of medications requiring gastric acidity for absorption include:

  • Dasatinib

  • Delavirdine mesylate

  • Cefditoren

  • Fosamprenavir 

  • Atazanavir

  • Erlotinib

  • Ketoconazole

  • Itraconazole

  • Ledipasvir/sofosbuvir

  • Nilotinib

  • Rilpivirine 

Famotidine dosage for pets

Famotidine is used in cats, dogs, and small mammals to reduce stomach acid production and adverse effects associated with acid reflux. Famotidine intended for veterinary use should not be used in humans. Similarly, pets should not be given famotidine that was intended for human use. 

In pets, famotidine can be given in tablet or liquid form. In a clinical setting, famotidine may also be administered intravenously. It is typically given to dogs and cats in the morning on an empty stomach, prior to the first meal of the day. 

The famotidine dosage for dogs and cats is typically 0.25-0.5 mg/lb, administered twice per day.

How to take famotidine

Famotidine for self-administration should be taken by mouth, once or twice per day, 10 minutes to one hour before a meal. For duodenal ulcers, take famotidine at bedtime. For all other indications, take famotidine at a time you will remember each day. 

  • It is important to follow medical advice and take this medication exactly as directed. Important drug information can be found on the packaging or package insert. 

  • Patients should disclose a full medication list, all medical conditions, and any allergies before taking famotidine. It is important to disclose all medications and supplements, any medical conditions the patient has, and any allergic reactions or adverse reactions to medications in the past in order to avoid a potential allergic response. 

  • If you are prescribed this medication, complete all doses even if you feel well after taking the first few. The dose may need to be adjusted several times to find what works best.

  • Swallow the tablets whole. Do not cut, crush or chew them unless you are taking the chewable tablet formulation. 

  • Oral suspensions should be measured with a measuring cup or spoon. 

  • For all other indications except heartburn relief, famotidine may be taken with food.

  • Famotidine for heartburn relief may be taken with antacids. 

  • If you miss a dose of this medication, take the next dose as soon as you remember. 

  • Store this medication at room temperature (68 to 77 degrees Fahrenheit). 

  • Patients should immediately seek medical care if they experience any type of allergic reaction to this medication. Allergic responses should be reported and treated as early as possible. Any type of serious allergic response should receive medical attention immediately. 

Famotidine dosage FAQs

How long can you take famotidine?

OTC famotidine should not be taken daily for more than several weeks at a time. If symptom resolution has not occurred, it is important to seek medical care, as a more serious underlying condition may exist. Famotidine is generally a very safe medication, with individuals taking it over years of time. Clinical studies have looked at famotidine use across a 7.5 year period of time and did not find an increased incidence of gastric cancer, as has been reported with long term use of proton pump inhibitors (PPI’s).

RELATED: Famotidine vs. omeprazole 

What is the maximum dosage for famotidine?

For most indications, and for OTC use, the maximum dose of famotidine is 40 mg per day, although it is also prescribed at 40 mg twice daily under the care of a physician. For some serious conditions, prescription famotidine may be dosed as high as 160 mg four times per day over a short period of time. 

What interacts with famotidine?

Famotidine has no absolute contraindications (reasons that it absolutely can not be used) for use outside of individuals who are allergic to the medication or any of its components. Cross-sensitivity between H2-receptor antagonists has been observed, thus famotidine should not be used in individuals with a history of hypersensitivity to ranitidine, cimetidine, or nizatidine. See a full list of possible drug interactions here.

What happens when you mix famotidine and alcohol?

Famotidine should not be taken with alcohol. This medication is used to treat conditions where there is, or there may be, risk of significant damage to the stomach, esophagus, and intestines. Drinking alcohol while taking this medication could result in severe worsening of symptoms and lack of therapeutic benefit. 

Is it safe to take famotidine during pregnancy or while breastfeeding?

No specific evidence of infertility or harm to the fetus were shown in reproductive studies with famotidine and animals. However, there are no adequate or well-controlled studies in pregnant women. Since reproductive animal studies are not always representative of a human response, famotidine should be used in pregnancy only if needed. 

Studies have shown detectable famotidine levels in animal and human breast milk. While the concentration of famotidine found in breastmilk is lower than what is typically dosed to infants, the FDA notes that famotidine has the potential to cause serious harm in nursing infants. Thus, you should discuss with your healthcare provider whether it is safe to continue to take this medication while breastfeeding. Most pediatricians and the American Academy of Pediatrics agree that it is safe for a nursing mother to take famotidine while breastfeeding. If you have questions about taking this medication while breastfeeding, speak with your or your child’s healthcare provider. 

Medically reviewed by Jesse P. Houghton, MD, FACG
Fellow of the American College of Gastroenterology

Jesse P. Houghton, MD, FACG, was born and raised in New Jersey, becoming the first physician in his entire family. He earned his medical degree from New Jersey Medical School (Now Rutgers Medical School) in 2002. He then went on to complete his residency in Internal Medicine and his fellowship in Gastroenterology at the Robert Wood Johnson University Hospital in 2005 and 2008, respectively. He moved to southern Ohio in 2012 and has been practicing at Southern Ohio Medical Center as the Senior Medical Director of Gastroenterology since that time.

Dr. Houghton is the author of What Your Doctor Doesn't (Have the Time to) Tell You: The Gastrointestinal System. He is also an Adjunct Clinical Associate Professor of Medicine at the Ohio University School of Osteopathic Medicine. He has been in practice since 2008 and has remained board-certified in both Internal Medicine and Gastroenterology for his entire career. He has lent his expertise to dozens of online articles in the medical field.

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Written by Georgia C. Yalanis, MD
Medical Doctor

Georgia C. Yalanis, MD, MSc, is a physician-scientist with expertise in “bench-to-bedside” medicine. She uses translational medicine applications to help clients and companies create products that are scientifically and technologically advanced while still being clinically useful. She has worked in the regulatory and biotech space and has a passion for individuals being empowered to make informed decisions about their medical and health care.

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