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 Oct 21, 2025  •  Published Jan 27, 2022
Fact Checked
In this article:

Key takeaways

  • The standard famotidine dosage for heartburn in adults and children is 10–20 mg taken before a meal.

  • The maximum dose of famotidine depends on the condition being treated.

  • Famotidine is available as tablets, oral suspension, and injections.

  • The best time to take OTC famotidine is during a bout with heartburn or 30 to 60 minutes before eating or drinking.

  • The best time to take prescription famotidine is at bedtime.

  • Do not take famotidine if you are allergic to famotidine or other H2 blockers.

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How much famotidine should I take? Quick reference
Patient Typical starting dose Standard dosage Maximum dose
Heartburn 10–20 mg taken 30–60 minutes before eating OR As needed to relieve heartburn 10–20 mg taken 30–60 minutes before eating OR As needed to relieve heartburn 40 mg/day
Active ulcers 40 mg once daily or 20 mg twice daily 40 mg once daily or 20 mg twice daily 80 mg/day or 40mg twice daily
GERD 20–40 mg twice daily 20–40 mg twice daily 80 mg/day or 40mg twice daily
Pediatric dosage 0.5–1 mg/kg for children <110 pounds OR 40 mg/day for children >110 pounds 0.5–1 mg/kg for children <110 pounds OR 40 mg/day for children >110 pounds 40 mg/day

The dosages listed are general guidelines; your healthcare provider may adjust your dose based on individual health factors.

Famotidine is a prescription and over-the-counter drug FDA-approved to treat heartburn, ulcers, gastroesophageal reflux disease (GERD), esophagus erosion, and excessive stomach acid. As an H-2 receptor antagonist, famotidine reduces the acid produced by the stomach. When used for heartburn, famotidine is typically taken before eating. When taken to treat ulcers or chronic GERD, both OTC and prescription strength famotidine is taken once or twice every day without regard to food.

Famotidine forms and strengths

Famotidine is available in both generic and brand-name formulations (Pepcid AC and Zantac). There are three dosage forms: 

  • Tablets: 10 mg, 20 mg, 40 mg (Rx)

  • Oral suspension: 40 mg/5 ml (Rx)

  • Intravenous injection solution: 10 mg/ml, 20 mg/50 ml (Rx)

Detailed famotidine dosage chart for adults
Indication Starting dosage Standard dosage Maximum dosage
Self-administration for heartburn, acid indigestion, or sour stomach 10–20 mg tablet taken 30–60 minutes before eating  OR As needed to relieve heartburn 10–20 mg tablet taken 30–60 minutes before eating  OR As needed to relieve heartburn 40 mg per day 
Active stomach ulcer 40 mg tablet taken at bedtime  OR  20 mg IV infusion every 12 hours 40 mg tablet taken at bedtime for up to 8 weeks  OR  20 mg IV infusion every 12 hours 80 mg/day
Active duodenal ulcer 40 mg tablet taken at bedtime  OR  20 mg tablet taken twice daily  OR  20 mg IV infusion every 12 hours  40 mg tablet taken at bedtime for up to 8 weeks  OR  20 mg tablet taken twice per day for up to 8 weeks  OR  20 mg IV infusion every 12 hours 80 mg/day Duodenal ulcer, prevention 20 mg tablet taken at bedtime  20 mg tablet taken at bedtime  40 mg/day  GERD 20 mg tablet taken twice per day  20 mg tablet taken twice per day for up to 6 weeks 40 mg/day  GERD with erosive esophagitis  20–40 mg tablet taken twice per day  20–40 mg tablet taken twice per day for up to 12 weeks 80 mg/day  Pathological hypersecretory conditions (e.g., Zollinger-Ellison syndrome)  20 mg tablet taken 4 times per day OR 20 mg IV twice per day 20–60 mg tablet taken 4 times per day OR 20 mg IV twice per day 640 mg/day  NSAID-induced ulcer prophylaxis (off-label) 40 mg tablet taken twice per day  40 mg tablet taken twice per day  80 mg per day 

Detailed famotidine dosage chart for children
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/kg/day taken once or twice per day for 8 weeks 40 mg/day
GERD <3 months old 0.5–1 mg/kg/dose once per day for 4-8 weeks 
3–12 months old  0.5–1 mg/kg/dose once per day for 4-8 weeks 40 mg/day
GERD without esophagitis or ulcers 1–16 years of age 0.5 mg/kg twice daily 40 mg/day
All other indications Children weighing more than 40 kg (88 lbs.) Adult dosages Adult dosages

Personalized dosing considerations

The risk of toxic side effects may be increased in individuals with kidney disease or in older adults taking famotidine. Renal dose adjustments should be made for adults and children with renal impairment. For most indications, dosages for people with mild to moderate renal impairment (creatinine clearance 30–59 mL/min) are 20 mg taken once daily or 40 mg taken once every other day. For severely impaired renal function (creatinine clearance <30 mL/min), patients should only take 20 mg every other day.

No dosage adjustments are required in people with liver (hepatic) problems.

Famotidine safety info

When taken as directed, famotidine is a safe drug with relatively mild adverse effects— usually headache, dizziness, drowsiness, and constipation. 

Contraindications include any serious allergic reaction to famotidine or other histamine-2 receptor antagonists, such as cimetidine. 

Do not rely on OTC famotidine if you have trouble swallowing, bloody vomit, or black and tarry stools—seek professional medical care right away. 

Stopping famotidine will not cause withdrawal effects, so the dose will not have to be gradually reduced when it’s time to stop.

RELATED: Famotidine side effects and how to avoid them

How to take famotidine

Famotidine can be taken with or without food. Taking it with food may prevent gastrointestinal issues. 

Famotidine should be taken by mouth, once or twice per day. To prevent heartburn, take the tablet with water 30 minutes to one hour before a meal. To relieve heartburn, swallow the tablet whole with water. 

If needed, OTC famotidine can be taken with antacids like Tums, Rolaids, or Gaviscon. 

For active ulcers, take famotidine at bedtime unless instructed otherwise. For all other indications, follow the doctor’s instructions or prescription label.

Swallow famotidine tablets whole without chewing or breaking them.

Shake the oral suspension vigorously for five to 10 seconds before measuring a dose. Use a calibrated measuring cup, spoon, or syringe to measure the dose.

If you miss a dose of OTC famotidine, take the missed dose if needed. Ask the prescriber how to handle a missed dose of prescription famotidine. 

Store famotidine at room temperature (68 to 77 degrees Fahrenheit). 

RELATED: What’s the best time to take famotidine?

Famotidine dosage FAQs

How long can you take famotidine?

OTC famotidine should not be taken for more than 14 days without consulting a doctor. If heartburn symptoms do not improve, a more serious underlying condition may be the cause. 

Prescription famotidine may be used for limited periods for some conditions (like ulcers), while long-term use may be needed for others (chronic GERD). 

What is the maximum dosage for famotidine?

For heartburn relief and some medical conditions, the maximum dose of famotidine is 40 mg per day. For some serious conditions, prescription famotidine may be used at daily doses of 80 mg or more. 

What interacts with famotidine?

Famotidine has potential drug interactions because it reduces gastric acid levels. Many medications are not properly absorbed when stomach acid is low, so they may not work as well when taken with famotidine. However, you still have stomach acid present even while taking famotidine—it just reduces the acid level.

If you’re taking critical prescription drugs, don’t start taking OTC famotidine without consulting a doctor. For prescription famotidine, tell the prescriber about all the prescription drugs and OTC medications you are taking.

Don’t take famotidine with other stomach acid reducers such as other H2 blockers (e.g., cimetidine) or proton pump inhibitors (e.g., omeprazole) unless instructed to do so by a doctor.

What happens when you mix famotidine and alcohol?

Do not drink alcohol when taking famotidine. Alcohol can worsen many of the symptoms famotidine is meant to relieve. 

RELATED: Is it safe to mix alcohol with heartburn medication?

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

Famotidine is probably safe for pregnant or breastfeeding women to take, but get medical advice before using the OTC version.

What is the dosage of famotidine for pets?

Veterinarians use famotidine tablets or liquid in dogs and cats with acid reflux, ulcers, or other stomach acid problems. The dosage for dogs and cats is typically 0.25-0.5 mg/lb, administered twice daily.

Sources

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.

... 
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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