What Is Famotidine and What Does It Treat?
Famotidine is an acid-reducing medication used in dogs to ease the signs of stomach upset and acid-related conditions. It is best known by the human brand name Pepcid (and Pepcid AC), and is used off-label in dogs — where it is a familiar, widely used and generally very safe medicine.
Famotidine belongs to a class of drugs called H2 receptor antagonists (“H2 blockers”). It works by blocking histamine H2 receptors on the acid-producing cells of the stomach lining. Reducing the signal to those cells means less stomach acid is produced, which lowers acidity in the stomach.
Veterinarians use famotidine to help dogs with conditions where excess or poorly tolerated stomach acid is a problem, such as:
- Gastritis — inflammation of the stomach lining
- Acid reflux and esophagitis
- Stomach (gastric) ulcers, often alongside other treatment
- Acid-related nausea, vomiting and stomach discomfort
- Acid protection in some dogs with kidney disease or on ulcer-prone medications
Two things are worth understanding. First, famotidine reduces acid; it does not treat the underlying cause of a stomach problem — so persistent or serious signs still need a veterinary diagnosis. Second, while famotidine itself is available over the counter for people, you should still use it for a dog only on veterinary advice, and only the plain product (see the safety section). Use the calculator above to understand the typical dose. For more, see PuppaDogs’ guides to famotidine for dogs and Pepcid for dogs.
How the Famotidine Dosage Calculator Works
The calculator estimates a famotidine dose from your dog’s body weight and a chosen dose level. It then:
- Shows the 0.5–1 mg/kg dose range and the selected dose.
- Converts it into a number of 10 mg or 20 mg tablets.
- Lets you choose once- or twice-daily dosing.
- Flags kidney disease and other cautions.
Enter your dog’s weight, choose the dose level, frequency and tablet strength, tick any health considerations, then press Calculate Dose.
How Famotidine Doses Are Calculated for Dogs
The Standard Dose
The usual off-label oral famotidine dose for dogs is approximately:
0.5–1 mg/kg of body weight, every 12 to 24 hours.
Veterinarians often start at the lower end (around 0.5 mg/kg) and adjust based on the response. It is commonly given once or twice daily, and is frequently given shortly before a meal.
Factors That Influence the Dose
- Body weight is the main driver of the dose.
- Kidney function matters because famotidine is eliminated largely by the kidneys — dogs with kidney disease may need a lower or less frequent dose.
- Other medications — because famotidine changes stomach acidity, it can affect how some other drugs are absorbed.
Famotidine Dosage Chart for Dogs
This chart shows the per-dose range. It is a reference only — your veterinarian’s recommendation takes priority.
| Dog weight | Per-dose range (0.5–1 mg/kg) | Frequency |
|---|---|---|
| 5 kg (11 lb) | 2.5–5 mg | every 12–24 h |
| 10 kg (22 lb) | 5–10 mg | every 12–24 h |
| 20 kg (44 lb) | 10–20 mg | every 12–24 h |
| 30 kg (66 lb) | 15–30 mg | every 12–24 h |
| 40 kg (88 lb) | 20–40 mg | every 12–24 h |
How to Give Famotidine to Your Dog
- Often given before a meal — many vets advise giving famotidine about 30 minutes before food, though it can be given with or without food.
- Be consistent with timing.
- Hide the tablet in a small treat or pill pocket.
- Missed dose: give it when you remember unless the next dose is close, then skip it — never double up.
Side Effects and Safety Warnings
Famotidine is one of the safest and best-tolerated medications used in dogs. Side effects are uncommon, and when they occur are usually mild — such as a brief change in appetite or mild digestive upset. It has a wide safety margin.
The One Rule That Really Matters: Use Plain Famotidine Only
The most important safety point with famotidine is product selection. You must use plain famotidine — the single-ingredient product. Do not use “Pepcid Complete” or any combination product, because those contain added antacids (such as calcium carbonate and magnesium hydroxide) or other ingredients that are not part of the intended treatment and can cause problems. Always read the full ingredient list, and if the package lists anything other than famotidine as an active ingredient, do not use it.
When to Use Caution
- Kidney disease — famotidine is cleared by the kidneys; the dose may need adjusting.
- Pregnant or nursing dogs — use only with veterinary approval.
- Other medications — because famotidine reduces stomach acid, it can change the absorption of some drugs; tell your vet everything your dog takes.
Famotidine Treats the Symptom, Not the Cause
This is the key clinical message. Famotidine can make a dog with acid-related stomach upset more comfortable, but a problem serious enough to need it is a problem worth understanding. Ongoing vomiting, a persistently poor appetite, weight loss, black or tarry stool, or signs of pain should always prompt a proper veterinary work-up, not just continued acid suppression.
Famotidine and Other Acid-Related Medications
Famotidine is one of several tools for managing stomach acid in dogs. Depending on the situation, your veterinarian might combine it with, or choose instead, a different medication — for example a proton-pump inhibitor, or the protective coating agent sucralfate. PuppaDogs has related resources including the sucralfate dosage calculator and a guide to the older H2 blocker ranitidine. Your vet will choose the right combination for your dog’s specific problem.
Treatment Duration
Famotidine is usually used as a short-to-medium course — often days to a few weeks — to settle an acid-related problem while the underlying issue is addressed. Some dogs with chronic conditions use it longer-term under veterinary supervision. Your veterinarian will set the appropriate length.
Conclusion
Famotidine (Pepcid) is a safe, well-tolerated, widely used acid-reducing medication for dogs, dosed at roughly 0.5–1 mg/kg every 12–24 hours. The calculator above gives you that estimate and converts it into tablets. The keys to using it well are simple: use only plain famotidine (never Pepcid Complete or a combination product), confirm the plan with your veterinarian, and remember that famotidine eases acid-related discomfort but does not replace finding out why your dog’s stomach is upset.
Frequently Asked Questions
How much famotidine can I give my dog?
The usual off-label famotidine (Pepcid) dose for dogs is about 0.5-1 mg/kg of body weight, given every 12 to 24 hours, often started at the lower end. As a guide that is roughly 5-10 mg for a 22 lb dog. Famotidine should be used in dogs only on veterinary advice, so confirm the dose with your vet.
Can I give my dog Pepcid AC?
Plain Pepcid AC (famotidine on its own) is the form used off-label in dogs, on veterinary advice. However, you must never use Pepcid Complete or any combination product, because those contain added antacids and other ingredients. Always check the label and use only single-ingredient famotidine.
What is famotidine used for in dogs?
Famotidine is an H2 blocker that reduces stomach acid. Veterinarians use it in dogs for acid-related conditions such as gastritis, acid reflux and esophagitis, stomach ulcers (alongside other treatment), and acid-related nausea or stomach discomfort. It reduces acid but does not treat the underlying cause.
How long does famotidine take to work in dogs?
Famotidine usually begins reducing stomach acid within an hour or two of a dose, so dogs with acid-related discomfort often seem more comfortable on the same day. For a fuller effect, it is given consistently over a short course while the underlying problem is addressed.
Is famotidine safe for dogs?
Famotidine is one of the safest and best-tolerated medications used in dogs, with a wide safety margin and uncommon, usually mild side effects. The main precautions are to use only plain famotidine, to adjust the dose in dogs with kidney disease, and to use it only with veterinary advice for pregnant or nursing dogs.
Should famotidine be given on an empty stomach?
Famotidine can be given with or without food, but many veterinarians advise giving it about 30 minutes before a meal so that acid is reduced as the dog eats. The most important things are to be consistent and to follow your veterinarian’s specific instructions.
Related PuppaDogs Calculators
Continue building your dog’s personalised care plan with these related PuppaDogs calculators:
- Dog Pregnancy / Whelping Due-Date Calculator
- Puppy Weight Predictor (Adult Weight Calculator)
- Heatstroke Risk Calculator for Dogs
- Bloat (GDV) Risk Calculator for Dogs
- Dog Life Expectancy Calculator (Breed, Body Condition, Lifestyle)
- Spay/Neuter Timing Calculator for Dogs (Breed-Specific)
References & Further Reading
The dosing ranges and safety information on this page are drawn from the following veterinary references. Always defer to your own veterinarian and the manufacturer’s label for your specific product.
- Plumb DC. Plumb’s Veterinary Drug Handbook. 10th ed. Hoboken, NJ: Wiley-Blackwell, 2023 – famotidine monograph.
- Marks SL, et al. ACVIM consensus statement: Rational administration of gastrointestinal protectants to dogs and cats. Journal of Veterinary Internal Medicine, 2018.
- Merck Veterinary Manual. Gastrointestinal ulceration; H2-receptor antagonists in small animals. merckvetmanual.com.
- Veterinary Partner (VIN). Famotidine (Pepcid) for dogs and cats. veterinarypartner.vin.com.
- PuppaDogs. Famotidine for Dogs: Benefits, Dosage, Side Effects, and More. puppadogs.com.
