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Pepcid Dosage Calculator for Dogs

Pepcid is a brand name for famotidine, a medicine that lowers stomach acid. The published dog dose is 0.5 to 1 mg/kg by mouth, every 24 hours (Merck Veterinary Manual), roughly 0.25 to 0.5 mg per pound. Enter your dog’s weight for the amount and a tablet count. Use plain famotidine only, and ask your vet first, especially if your dog is vomiting or will not eat.

By Sikander Malik · Updated October 19, 2026 · Sources

lb

Tablet strength

Dose from the Merck Veterinary Manual antiulcerative table (famotidine 0.5 to 1 mg/kg, every 24 hours). Plain famotidine only. Tablets split in halves.

Ask your vet before giving any medicine, and confirm the amount for your dog.

Typical dose (start low)

0.5× 10 mg tablets

= 5 mg (about 0.6 mg/kg), every 24 hours.

Full range5 mg–9 mg (0.5 tablets)
Never exceed9 mg (1 mg/kg) per dose
Use plain famotidine only, not “Pepcid Complete”. See the box below before you buy.

An estimate, not veterinary advice. Reviewed against the Merck Veterinary Manual antiulcerative drugs table and its gastrointestinal ulcer drug information, October 2026. Medical disclaimer.

Buy plain famotidine, not Pepcid Complete

Use a product whose only active ingredient is famotidine, such as plain Pepcid AC (10 mg) or Maximum Strength (20 mg). Check the active ingredient panel, because some products are different:
  • “Pepcid Complete” also contains calcium carbonate and magnesium hydroxide (two antacids). Do not use it.
  • Avoid any combination or flavoured product whose ingredients you cannot verify.

How much Pepcid can I give a dog?

Pepcid (famotidine) lowers stomach acid by blocking the H2 receptors on the cells that produce it. The published dog dose is 0.5 to 1 mg/kg by mouth, every 24 hours (Merck Veterinary Manual), which is roughly 0.25 to 0.5 mg per pound. It comes as 10 mg and 20 mg tablets; pick the strength that divides most cleanly for your dog, in half-tablet steps. The calculator leads with the lower amount and shows the full range. Confirm the amount, and how many days to use it, with your vet.

When it is not just an upset stomach

Famotidine eases symptoms; it does not fix the underlying cause. Vomiting that will not stop, black or tarry stool, blood, a swollen belly, or a dog that will not eat needs a vet visit, not just an antacid. Do not use it to put off care for a dog that is unwell.
Pepcid dose by weight
Pepcid dose for dogs by weight
WeightDose per dose10 mg tablets
10 lb3 mg–4 mgask your vet
12 lb3 mg–5 mg0.5
20 lb5 mg–9 mg0.5
40 lb10 mg–18 mg1–1.5
60 lb14 mg–27 mg1.5–2.5
80 lb19 mg–36 mg2–3.5
100 lb23 mg–45 mg2.5–4.5
0.5–1 mg/kg, every 24 hours. Tablet counts are in half steps and never exceed 1 mg/kg. Where no half tablet fits, ask your vet for a liquid or a compounded dose.
Source: Merck Veterinary Manual, Antiulcerative Drugs table (famotidine, dogs, 0.5–1 mg/kg, PO, q24h).

Cats: ask your vet, no dose here

We don’t list a cat dose because our source doesn’t give one specific to cats. Famotidine is used in cats, but at amounts we cannot confirm from a free, public reference, so we will not print a number. Ask your vet for a cat’s dose.

Who should not take it

Famotidine is usually well tolerated. Talk to your vet before giving it if your dog:

  • has kidney or liver disease;
  • has heart disease;
  • is pregnant or nursing;
  • is taking other medicines, which it can interact with;
  • is very old, very young or unwell.

General precautions for H2 blockers; see the Merck Veterinary Manual gastrointestinal ulcer drug information. Famotidine is cleared by the kidneys, so your vet may adjust it for a dog with kidney disease.

Overdose signs

Famotidine has a wide margin, so a single extra tablet rarely causes serious harm. A large overdose could cause:

  • vomiting or restlessness;
  • a fast or irregular heartbeat;
  • pale gums or weakness from low blood pressure.

If your dog ate a lot of tablets, or you gave much more than the amounts above, call your vet or the ASPCA right away.

If you think your dog had too much

Call your vet or the ASPCA Animal Poison Control Center at (888) 426-4435 (a consultation fee may apply), or go to your nearest emergency vet.

Questions owners ask

How often can I give Pepcid to a dog?
The published dog dose is once a day (every 24 hours), per the Merck Veterinary Manual antiulcerative table. Some vets prescribe it every 12 hours for certain problems. Follow your vet’s instructions.
Should I use 10 mg or 20 mg tablets?
Both are plain famotidine. Pick the strength that divides most cleanly for your dog’s weight, in half-tablet steps. Small dogs usually use the 10 mg tablet; larger dogs may use 20 mg. The calculator shows both.
Can I use Pepcid Complete?
No. "Pepcid Complete" adds calcium carbonate and magnesium hydroxide. Use a product whose only active ingredient is famotidine, and read the box every time.
When should I see a vet instead?
Vomiting that will not stop, black or tarry stool, blood, a swollen belly, or a dog that will not eat needs a vet, not just an antacid. Famotidine eases symptoms; it does not fix the cause.
Can I give Pepcid to my cat?
Ask your vet. We do not show a cat dose here because our source does not give a cat-specific amount we can verify.

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Sources

An estimate, not veterinary advice. Reviewed against the Merck Veterinary Manual antiulcerative drugs table and its gastrointestinal ulcer drug information, October 2026. Medical disclaimer.