Pepcid Dosage Calculator for Dogs

Calculate the correct famotidine (Pepcid) dose for your dog by weight and condition. Always confirm with your veterinarian before administering.

Important Safety Warnings

  • Do NOT use Pepcid AC Complete — it contains calcium carbonate and magnesium hydroxide, which are different products not appropriate for dogs
  • Do NOT give antacids within 2 hours of famotidine — they reduce its absorption
  • Dogs with kidney disease, liver disease, or heart conditions require veterinary dosing guidance
  • Use plain famotidine only — check the active ingredient label before purchasing

Famotidine (brand name: Pepcid) is one of the most commonly used over-the-counter medications in veterinary medicine. Whether your dog has acid reflux, is on NSAIDs that irritate the stomach, or has a bout of vomiting, this calculator helps you determine the right dose based on your dog's weight and condition — without guesswork.

What Is Famotidine (Pepcid) and Why Do Vets Recommend It for Dogs?

Famotidine is an H2 receptor antagonist — a type of medication that works by blocking histamine H2 receptors in the stomach lining. These receptors are part of the mechanism that signals the stomach to produce hydrochloric acid. By blocking them, famotidine significantly reduces the amount of acid the stomach produces, providing relief from acid-related conditions.

Unlike antacids (which neutralize existing acid), famotidine prevents acid production at the source. This makes it more effective for sustained acid control, particularly for conditions like GERD, esophagitis, and gastric ulcers. It also has a longer duration of action than most antacids — typically 12–24 hours from a single dose.

Vets recommend famotidine over other H2 blockers (like cimetidine or ranitidine) because it has fewer drug interactions, a better safety profile in dogs with mild organ disease, and is readily available OTC in the correct strengths for most dog sizes.

The Merck Veterinary Manual lists the standard dose as 0.5–1.0 mg/kg, given every 12–24 hours depending on the condition. This calculator uses that exact reference range.

How the Pepcid Dosage Calculator Works

The calculator converts your dog's weight from pounds to kilograms, then applies the appropriate dose multiplier based on the condition selected:

  • Vomiting/Nausea and General GI Upset: 0.5 mg/kg (the low end of the therapeutic range, appropriate for short-term symptomatic treatment)
  • Acid Reflux/GERD and Ulcer Prevention: 1.0 mg/kg (the full therapeutic dose, appropriate for acid suppression)

It then calculates the tablet count by dividing the dose in mg by your selected tablet strength, rounding to the nearest half-tablet for practical administration.

If the calculated dose falls below 5 mg, the calculator flags this as a "very small dose" and recommends liquid famotidine — because splitting a 10 mg tablet into quarters introduces too much dosing error for small dogs.

Conditions Famotidine Treats in Dogs

Acid Reflux / GERD / Esophagitis

Dogs with chronic acid reflux often show symptoms like grass-eating, lip-licking, gulping, regurgitation (separate from vomiting), and loss of appetite — particularly in the morning before eating. Famotidine reduces the acid that backs up into the esophagus, providing symptomatic relief and allowing the esophageal lining to heal.

Gastric Ulcer Prevention (NSAID/Aspirin Use)

Dogs on non-steroidal anti-inflammatory drugs (NSAIDs) like carprofen (Rimadyl), meloxicam (Metacam), or deracoxib (Deramaxx) are at risk of developing gastric ulcers because NSAIDs suppress prostaglandins that protect the stomach lining. Famotidine is frequently prescribed alongside NSAID therapy to reduce this risk.

Vomiting and Nausea

While famotidine is not a primary antiemetic (it does not directly block the vomiting reflex the way metoclopramide or maropitant do), it helps when vomiting is triggered or worsened by excess stomach acid. A common presentation is dogs who vomit yellow bile in the morning — a classic sign of acid reflux-induced nausea on an empty stomach.

General GI Upset

For dogs who ate something unusual or are experiencing transient stomach upset without a clear cause, a short 2–3 day course of famotidine at the lower dose can help settle the stomach while you monitor for improvement.

What Pepcid Does NOT Treat

Famotidine is an acid reducer, not a broad GI medication. It does not treat:

  • Intestinal infections or parasites — these require appropriate antiparasitic or antibiotic treatment
  • Pancreatitis — famotidine may be used as a supportive therapy but is not the primary treatment
  • Inflammatory bowel disease (IBD) — requires dietary management and often immunosuppressive therapy
  • Foreign body obstruction — this is a surgical emergency; famotidine cannot address a physical blockage
  • Parvovirus or other serious infections — requires intensive veterinary care
  • Motion sickness — use a specific antiemetic like maropitant (Cerenia) for this purpose

How to Give Famotidine to Your Dog

  1. Verify the product: Check the label to confirm the active ingredient is famotidine only. Do not use Pepcid AC Complete.
  2. Time the dose correctly: For acid reflux or nausea, give 30–60 minutes before the first meal of the day. For ulcer prevention, timing relative to food is flexible.
  3. Hide in food if needed: Most dogs accept tablets hidden in a small amount of peanut butter, cheese, or pill pocket. Avoid large amounts of food before the pre-meal dose.
  4. Cut tablets carefully: Use a pill splitter for accurate halving. Do not crush unless confirmed with your vet — some formulations should not be crushed.
  5. Monitor response: You should see improvement in symptoms within 24–48 hours for acid-related conditions. If there is no improvement after 3 days, contact your vet.
  6. Do not stop abruptly for long courses: For dogs on famotidine for more than 2 weeks, discuss a tapering plan with your vet to avoid acid rebound.

Frequently Asked Questions

Can I give my dog regular Pepcid from the pharmacy?

Yes — as long as it is plain famotidine (Pepcid AC original, or store-brand famotidine 10 mg). Always check the inactive ingredients and active ingredient panel to confirm famotidine is the only active drug.

Is 10 mg of famotidine safe for a small dog?

For dogs under ~15 lbs, 10 mg may be at or above the high end of the therapeutic range. Use the calculator to check — if the recommended dose is under 5 mg, ask your vet about liquid famotidine for more precise dosing.

Can famotidine cause side effects in dogs?

Famotidine is generally very well-tolerated. Rare side effects include decreased appetite, loose stools, or paradoxical vomiting. Dogs with kidney disease should be dosed conservatively, as famotidine is partly renally excreted.

Can I give famotidine with other medications?

Famotidine has relatively few drug interactions compared to other H2 blockers. However, it can reduce the absorption of drugs that require acidic conditions (like ketoconazole and itraconazole). Space antacids at least 2 hours from famotidine.

Why does my dog vomit yellow bile in the morning?

Morning yellow bile vomiting is a classic sign of bilious vomiting syndrome — acid and bile accumulating in an empty stomach overnight. Famotidine given at night or before the morning meal often resolves this. A late-night snack before bed can also help.

How long does famotidine take to work in dogs?

Famotidine is absorbed quickly and typically reaches peak effect within 1–3 hours of administration. For pre-meal dosing (acid reflux), giving it 30–60 minutes before food takes advantage of this timing to suppress acid before the meal stimulates more production.

Is famotidine better than omeprazole for dogs?

Omeprazole (Prilosec) is a proton pump inhibitor (PPI) and provides stronger, longer-lasting acid suppression than famotidine. For severe acid reflux, esophagitis, or confirmed ulcers, vets often prefer omeprazole. Famotidine is appropriate for mild-to-moderate conditions and short-term use.

What if I accidentally give my dog too much famotidine?

Famotidine has a wide safety margin. Accidental mild overdose (e.g., one extra tablet) is unlikely to cause serious harm in most dogs. However, if you are concerned, contact your vet or the ASPCA Animal Poison Control Center (888-426-4435).

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A Note on Veterinary Guidance

This calculator is designed to help you understand standard famotidine dosing guidelines as published in veterinary references. It is a starting point — not a replacement for veterinary advice. Your vet may recommend a different dose based on your dog's full health picture, current medications, and the severity of the condition.

If your dog has recurring or worsening GI symptoms, a proper diagnosis is important. Many conditions that cause vomiting, acid reflux, or GI upset in dogs have specific underlying causes — from dietary indiscretion to inflammatory bowel disease to liver disease — that require targeted treatment beyond acid suppression.