Famotidine (Pepcid®) for Dogs and Cats: Uses and Side Effects

Famotidine (Pepcid®) is an antacid veterinarians use to reduce stomach acid production in dogs, cats, and other animals.

It is commonly prescribed to help treat or prevent stomach ulcers and other gastrointestinal conditions associated with excess stomach acid.

Here’s how famotidine works, when it’s prescribed, possible side effects, dosing guidance, and important safety information.

What Is Famotidine?

Famotidine is an antacid used to reduce stomach acid production and help treat or prevent stomach ulcers in dogs, cats, and other animals.

Veterinarians commonly prescribe famotidine for:

• Dogs
• Cats
• Cattle
• Small mammals

It may also be used in combination with other medications to help treat stomach ulcers in horses.

FDA approval: Famotidine is FDA-approved for human use as a generic medication and under the brand names Pepcid® and Zantac 360™. (The original Zantac® containing ranitidine has been withdrawn from commercial markets.)

Although famotidine is not FDA-approved as a veterinary medication, veterinarians may legally prescribe it extra-label (off-label) when appropriate.

Compounded famotidine: In some cases, your veterinarian may recommend a compounded formulation when:

• Your pet has difficulty taking the commercially available formulation.
• The required dosage strength is not commercially available.
• Your pet is allergic to an ingredient in the FDA-approved medication.

Compounded medications are not FDA-approved. They are prepared by a veterinarian or licensed pharmacist to meet an individual patient's specific needs.

How Famotidine Works

Famotidine works by reducing the amount of acid produced in the stomach.

Famotidine is classified as an H2 blocker. It blocks H2 receptors in the stomach lining, preventing histamine from binding to them and reducing the secretion of stomach acid.

Lower stomach acid levels help protect the lining of the esophagus, stomach, and duodenum, allowing ulcers and irritated tissue to heal while helping prevent further damage.

How To Give Famotidine

Give famotidine exactly as directed by your veterinarian.

Administration tips:

• Follow the directions on the prescription label or those provided by your veterinarian.
• Famotidine is best given on an empty stomach, preferably before your pet's first meal of the day.
• If your pet develops stomach upset when the medication is given on an empty stomach, it may be given with a treat or a small amount of food.

Missed a Dose?

If you miss a dose of famotidine, contact your veterinarian for guidance. In many cases, they may recommend giving the missed dose when you remember. 

However, if it is almost time for your pet's next scheduled dose, they may advise skipping the missed dose and resuming the normal dosing schedule.

In most cases, do not give extra or double doses.

Famotidine Side Effects

Famotidine is generally well tolerated, and side effects are uncommon.

Possible side effects include:

• Loss of appetite
• Vomiting
• Diarrhea

Human Side Effects

Although famotidine is also prescribed for people, human and veterinary doses differ. Never take medication prescribed for your pet, and never give your pet medication prescribed for a person.

If you accidentally ingest a pet medication, contact your physician, seek medical attention, or call the National Poison Control Center at 800-222-1222.

Monitoring Your Pet

No specific monitoring is required while your pet is taking famotidine. However, your veterinarian may recommend routine testing based on your pet's health, other medications, or the condition being treated.

When To Call Your Veterinarian

Contact your veterinarian if:

• Your pet develops severe side effects.
• Your pet's condition worsens or does not improve with treatment.
• You suspect your pet has received an overdose.
• You have additional questions or concerns about using famotidine.

Famotidine Overdose

Famotidine has a wide margin of safety, but overdoses can still occur. The severity of symptoms depends on the amount ingested.

Moderate overdoses may cause:

• Vomiting
• Pale gums
• Drowsiness
• Restlessness
• A red tint to the ears and areas around the mouth

Large overdoses may cause:

• Low blood pressure
• High heart rate
• Collapse

If you suspect your pet has received an overdose, contact your veterinarian immediately, seek emergency veterinary care, or contact an animal poison control center. Consultation fees may apply.

• Pet Poison Helpline: (855) 764-7661
• ASPCA Animal Poison Control: (888) 426-4435

How To Store Famotidine

Store famotidine according to the product label to help maintain its safety and effectiveness.

Storage instructions:

• Store famotidine at controlled room temperatures between 68 F and 77 F (20 C–25 C).
• Always confirm storage instructions by reading the product label.
• Keep the container tightly closed to protect the medication from moisture and light.
• Store compounded formulations according to the instructions provided by the compounding pharmacy.
• Keep out of reach of children and pets.