Famotidine (Pepcid) for Dogs: Uses, Dosage & Safety

This article is educational only and does not replace care from your vet.

Famotidine is commonly used in dogs, but it is usually prescribed off-label, which means your vet is using a human medication in a veterinary-specific way. The right dose, timing, and treatment length depend on why your dog is having stomach signs, their weight, age, and whether they have kidney, liver, or heart disease.

Do not start famotidine at home for repeated vomiting, black stools, belly pain, weakness, collapse, or suspected toxin exposure. Those signs can point to ulcers, bleeding, an obstruction, pancreatitis, or another problem that needs prompt veterinary care.

Also check the product label carefully. Some human stomach products contain extra ingredients or flavored chewables that may not be appropriate for dogs.

Famotidine is an acid-reducing medication in the H2 blocker family. It works by blocking histamine-2 receptors in the stomach, which lowers acid production. In dogs, your vet may use it when stomach acid is contributing to nausea, reflux, esophagitis, gastritis, or ulcer irritation.

Although many pet parents recognize the brand name Pepcid, famotidine is not specifically FDA-approved for dogs. In veterinary medicine, it is commonly used off-label when your vet feels it fits the situation.

It is available as tablets and can also be given by injection in the hospital. Oral products are often sold in 10 mg and 20 mg strengths, but the best strength depends on your dog's size and the dose your vet recommends.

Famotidine can start working within about 1 to 3 hours, though visible improvement depends on the underlying problem. If a dog keeps vomiting or has an ulcer, the medication may be only one part of the treatment plan.

Your vet may recommend famotidine for dogs with stomach ulcers, acid reflux, esophagitis, gastritis, or vomiting linked to excess stomach acid. It is also sometimes used when a dog is at higher risk for stomach irritation, such as during certain illnesses or while taking medications that can affect the stomach lining.

In some dogs, famotidine is used for short-term relief of bilious vomiting, where a dog vomits yellow or foamy fluid on an empty stomach. It may also be part of a broader plan for dogs with kidney disease, mast cell disease, or other conditions that can increase stomach acid or ulcer risk.

That said, famotidine is not the right answer for every upset stomach. If your dog has frequent vomiting, diarrhea, abdominal pain, black stool, poor appetite, or weight loss, your vet may want to look for the cause rather than only reduce acid.

For long-term acid control, your vet may discuss other options such as omeprazole, pantoprazole, sucralfate, diet changes, anti-nausea medication, or diagnostics. The best choice depends on what problem is actually being treated.

Famotidine dosing in dogs varies by case, but commonly referenced veterinary ranges are about 0.5 to 1 mg/kg by mouth every 12 to 24 hours. Some vets use lower practical doses for mild, short-term stomach upset, while others use more structured dosing when treating ulcers or reflux.

Because dosing can change based on the goal of treatment, do not calculate a dose from a human label alone. Your vet may adjust the plan for puppies, senior dogs, and dogs with kidney, liver, or heart disease.

Famotidine is usually given on an empty stomach before a meal, especially if it is being used once daily. If your dog vomits or seems nauseated when it is given without food, your vet may tell you to give it with a small amount of food instead.

If you miss a dose, give it when you remember unless it is almost time for the next one. Do not double up. If your dog needs acid control for more than a short period, ask your vet whether famotidine is still the best option, since some dogs respond better to other acid-reducing medications over time.

Famotidine is generally well tolerated in dogs, and side effects are considered uncommon. When they do happen, the most reported signs are decreased appetite, vomiting, and diarrhea.

Less commonly, dogs may seem tired, have dry mouth, or show skin dryness. Injectable famotidine can also affect heart rate, which is one reason hospital use is monitored by veterinary staff.

Call your vet if your dog develops worsening vomiting, refuses food, seems weak, has black or tarry stool, vomits blood, or acts painful after starting famotidine. Those signs may reflect the underlying illness rather than the medication itself, but they still need prompt attention.

Dogs with kidney or liver disease, very old dogs, and pregnant or nursing dogs may need extra caution. In these cases, your vet may change the dose, choose a different medication, or recommend monitoring.

Famotidine can change how other medications are absorbed because it lowers stomach acid. That matters most for drugs that need an acidic stomach environment to work well.

Known veterinary cautions include azole antifungals such as ketoconazole or itraconazole, iron salts, cefpodoxime, cefuroxime, and cyclosporine. Your vet may adjust timing, choose a different acid reducer, or use another medication entirely.

It is also important to tell your vet about any over-the-counter products, probiotics, supplements, or compounded medications your dog takes. Even products that seem mild can affect the treatment plan.

Do not combine famotidine with another acid-reducing plan unless your vet tells you to. In ulcer cases, for example, combining an H2 blocker with a proton pump inhibitor is not usually helpful and may reduce the benefit of the proton pump inhibitor.