Omeprazole (Prilosec) Dosage Calculator for Dogs by Weight
Dose ranges on this page are published veterinary references for education only. Your veterinarian's prescribed dose always wins. When in doubt, call your vet first.
Omeprazole (Prilosec) is a proton pump inhibitor (PPI) — a stronger and longer-lasting acid suppressant than famotidine. Veterinarians prescribe it for stomach ulcers, severe reflux, and gastritis in dogs. The commonly published dose is 0.5–1 mg per kg of body weight, given once daily.
Important: omeprazole takes 3–5 days to reach its full effect — it is not a fast-acting fix. Use the calculator below for the daily range, and talk to your vet about duration and whether tapering is needed after long courses.
Dose calculator
Dosage chart by weight
| Dog weight | Dose range per dose |
|---|---|
| 5 lb | 1.1–2.3 mg |
| 10 lb | 2.3–4.5 mg |
| 15 lb | 3.4–6.8 mg |
| 20 lb | 4.5–9.1 mg |
| 30 lb | 6.8–13.5 mg |
| 40 lb | 9.1–18 mg |
| 50 lb | 11.5–22.5 mg |
| 60 lb | 13.5–27 mg |
| 80 lb | 18–36.5 mg |
| 100 lb | 22.5–45.5 mg |
Chart uses the same conservative range as the calculator (0.5–1 mg per kg of body weight). Always confirm with your veterinarian.
Common formulations
- Capsules — 20 mg capsules
Standard OTC size; 10 mg capsules also available
Use the calculator above to convert any of these sizes into an amount for your pet's weight.
How often to give it
Once daily (every 24 hours). 0.5–1 mg per kg of body weight.
Common veterinary uses
- Stomach and intestinal ulcers
- Severe acid reflux / esophagitis
- Gastritis
- Stomach protection during NSAID therapy (vet-directed)
Safety warnings
Possible side effects
- Vomiting
- Decreased appetite
- Gas
- Diarrhea
- Generally well tolerated at prescribed doses
- Omeprazole capsules contain enteric-coated granules. Do not crush or split in ways that destroy the coating unless your vet instructs a specific method.
- It takes 3–5 days to reach full effect — do not increase the dose because day one seemed weak.
Do not use (or ask your vet first)
- Do not stop abruptly after weeks of use without vet guidance — rebound acid production can occur; vets often taper
- Tell your vet about all other medications — omeprazole affects the absorption of some drugs
When to see a veterinarian
- Vomiting blood or coffee-ground material
- Black, tarry stools
- Persistent vomiting, diarrhea, or appetite loss
- Abdominal pain or bloating
- No improvement after the timeframe your vet described
Frequently asked questions
How much omeprazole can I give my dog?
The commonly published range is 0.5–1 mg/kg once daily — for example, a 20 kg (44 lb) dog would be about 10–20 mg per day, roughly one 20 mg capsule or less. Confirm with your vet.
How long does omeprazole take to work in dogs?
It starts reducing acid within hours, but full effect builds over 3–5 days of daily dosing. Give it time before judging whether it is working.
Can dogs take omeprazole long-term?
Veterinarians do prescribe longer courses for ulcer disease, with monitoring. Long-term use and stopping should both be vet-directed — abrupt stops after prolonged use can cause rebound acidity.
Can I give omeprazole with food?
It is usually given on an empty stomach, about 30–60 minutes before a meal, but follow your veterinarian's specific instructions.
Omeprazole vs famotidine for dogs — which is better?
Omeprazole suppresses acid more strongly and for longer, which is why vets choose it for ulcers and severe reflux. Famotidine acts faster for mild, occasional issues. Your vet decides based on the diagnosis.
Sources
- BSAVA Client Information Leaflet — Omeprazole (via Moorgate Vets, PDF)
- Vet eBooks — Omeprazole Dose by Weight for Dogs, Cats
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Dose ranges on this page are published veterinary references for education only. Your veterinarian's prescribed dose always wins. When in doubt, call your vet first.