Famotidine (Pepcid) for Dogs & Cats: Uses & Safety

This information is for educational purposes only. Never give your pet any medication without your veterinarian's guidance. Dosing, frequency, and safety depend on your pet's specific health profile.

Famotidine is an acid-reducing medication in the H2 receptor antagonist family. It lowers stomach acid by blocking histamine signals at the stomach lining. In veterinary medicine, your vet may use it to help protect irritated tissue in the stomach, esophagus, or upper small intestine.

Pepcid is the best-known human brand name, but veterinary use in dogs and cats is typically extra-label, meaning the medication is not specifically FDA-approved for pets even though vets commonly prescribe it. That matters because the right dose, timing, and whether it is appropriate at all depend on the reason your pet is sick.

Famotidine is available as tablets, liquid suspension, and injectable forms used in the hospital. It often starts working within 1 to 2 hours, though visible improvement depends on the underlying problem. If your pet is vomiting repeatedly, seems painful, or is acting weak, famotidine should not replace an exam because stomach upset can also be caused by pancreatitis, foreign material, kidney disease, toxin exposure, or other urgent problems.

Your vet may use famotidine for acid reflux, esophagitis, gastritis, and stomach or duodenal ulcer support. It is also sometimes used when stomach irritation is linked to stress, kidney disease, or other illnesses that can increase nausea and acid exposure.

In dogs, famotidine is often discussed for short-term support during acute vomiting or bilious vomiting episodes, especially when an empty stomach seems to make signs worse. In both dogs and cats, it may be part of a broader treatment plan rather than the only medication, because acid reduction alone does not fix dehydration, nausea, infection, obstruction, or inflammatory disease.

It is important to know that famotidine is not always the best long-term acid suppressant. For some pets with more severe ulcer disease or chronic reflux, your vet may recommend other options such as proton pump inhibitors or protective medications like sucralfate. The best choice depends on the diagnosis, how often signs happen, and whether your pet has kidney, liver, or heart disease.

Famotidine dosing for pets should come from your vet. Published veterinary references commonly list 0.5-1 mg/kg by mouth or injection every 12-24 hours, with Merck listing dogs at 0.5-1 mg/kg by mouth or IV every 24 hours and other veterinary references noting dogs and cats may be dosed every 12-24 hours depending on the case. Cats are often dosed individually based on body weight, kidney function, and the reason for treatment.

It is usually given on an empty stomach before a meal, especially if used once daily. If your pet 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. Do not double up if you miss a dose unless your vet specifically tells you to.

Not every Pepcid product is appropriate for pets. Some human combination products contain extra ingredients that may not be suitable. Strength also matters. A 10 mg tablet may be reasonable for one pet and far too much for another. Ask your vet which product, tablet strength, and schedule fit your pet's size and medical history.

Famotidine is usually well tolerated, and side effects are uncommon. When they do happen, reported effects include vomiting, diarrhea, reduced appetite, and occasionally dry mouth or dry skin. Injectable use can rarely slow the heart rate, which is one reason hospital dosing is monitored more closely.

Pets with kidney, liver, or heart disease, older pets, and pregnant or nursing pets may need extra caution. Because the drug can last longer in pets with reduced organ function, your vet may adjust the dose or choose a different medication.

Call your vet promptly if your pet becomes very sleepy, collapses, has pale gums, repeated vomiting, worsening diarrhea, or seems more painful after starting famotidine. Those signs may reflect overdose, dehydration, or an underlying illness that needs more than acid control. If your pet got into the bottle or ate an unknown amount, see your vet immediately.

Famotidine can change how well some medications are absorbed because certain drugs need a more acidic stomach environment to work properly. Veterinary references specifically advise caution with azole antifungals, cefpodoxime, cefuroxime, cyclosporine, and iron salts.

This interaction issue is one reason over-the-counter use can be tricky. A pet parent may be trying to help a vomiting dog or cat, but acid suppression can also blur the picture or reduce the effectiveness of another medication already being used for a skin infection, fungal infection, immune disease, or anemia.

Tell your vet about every product your pet takes, including supplements, probiotics, compounded medications, and flavored preventives. If your pet needs acid control and is also taking interacting drugs, your vet may adjust timing, choose a different stomach medication, or decide that treating the underlying cause is the better next step.