Famotidine vs Omeprazole: what's the difference?
How Famotidine and Omeprazole compare: what each is for, how it works, side effects and cost, side by side.
Last updated: October 2026 · 2 sources · see sources
Side by side
| Famotidine | Omeprazole | |
|---|---|---|
| Generic name | Famotidine | Omeprazole |
| Brand names | Pepcid | Prilosec, Gastrogard |
| For | Dogs and cats | Dogs and cats |
| Prescription | Over the counter (ask your vet first) | Over the counter (ask your vet first) |
| Used for | Lowers stomach acid for ulcers, stomach inflammation and acid reflux. [1] | Treats stomach and upper gut ulcers and helps prevent ulcers from drugs like NSAIDs. [2] |
| How it works | An H2 blocker: it cuts acid production in the stomach. [1] | A proton-pump inhibitor: it lowers acid more strongly than famotidine. [2] |
| Common side effects | Vomiting, diarrhea or low appetite; dry mouth. [1] | Vomiting, low appetite, gas and diarrhea. [2] |
| Use with care | Ask your vet first: some products contain extra ingredients. Use caution in older pets and pets with liver, kidney or heart disease. [1] | Use caution in pets with liver or kidney disease. Ask your vet before giving a human product. [2] |
| Full guide | Famotidine (Pepcid) guide | Omeprazole (Prilosec) guide |
Key differences
On the basics they are alike: same kind of animal, same way to get them. The differences are in how they work and what else they cover, shown in the table above.
Which one is right for my pet?
That is a call for your vet. They weigh your pet's age, weight, other health problems, other medicines and what you can realistically give at home.
Switching from Famotidine to Omeprazole is common, but do it only with your vet's plan.
Common questions
What is the difference between Famotidine and Omeprazole?
Both lower stomach acid. Omeprazole is a proton-pump inhibitor and lowers acid more strongly than famotidine.
Is Famotidine better than Omeprazole?
Neither is better for every pet. Your vet chooses based on your pet's species, age, health history, other medicines and what you can manage at home.
Can my pet take Famotidine and Omeprazole together?
Only if your vet says so. Some medicines in the same family should not be combined, and others are often used together. Always check before adding or switching.
Do Famotidine and Omeprazole need a prescription?
Famotidine: Many forms are sold without a prescription. Still, check with your vet first. Pet doses and safe products are not the same as for people. Omeprazole: Many forms are sold without a prescription. Still, check with your vet first. Pet doses and safe products are not the same as for people.
Related
This page is general information for planning, not veterinary advice. Talk to your vet about your own pet.