Omeprazole (Prilosec) Dosage Calculator for Cats 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 is used in cats for the same acid-related conditions as in dogs — ulcers, severe reflux, and gastritis. Veterinary references (BSAVA) list about 0.75–1 mg/kg once daily for cats; this calculator uses the conservative 0.5–1 mg/kg end of the published range.
As in dogs, full effect takes several days of daily dosing. Cat doses are small fractions of a capsule, so confirm the plan — including how to administer it — with your veterinarian.
Dose calculator
Dosage chart by weight
| Cat weight | Dose range per dose |
|---|---|
| 5 lb | 1.1–2.3 mg |
| 8 lb | 1.8–3.6 mg |
| 10 lb | 2.3–4.5 mg |
| 12 lb | 2.7–5.4 mg |
| 15 lb | 3.4–6.8 mg |
| 18 lb | 4.1–8.2 mg |
| 20 lb | 4.5–9.1 mg |
Chart uses the same conservative range as the calculator (0.5–1 mg per kg of body weight (conservative end of the published feline range)). Always confirm with your veterinarian.
Common formulations
- Capsules — 20 mg capsules
Cat doses are small fractions — ask your vet about compounding or administration method
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 (conservative end of the published feline range).
Common veterinary uses
- Stomach ulcers
- Severe reflux / esophagitis
- Gastritis (vet-directed)
Safety warnings
Possible side effects
- Vomiting
- Decreased appetite
- Diarrhea
- Usually well tolerated
- Do not crush enteric-coated granules unless your vet gives a specific method — the coating protects the drug from stomach acid.
- Full effect takes 3–5 days; do not raise the dose because the first day seemed weak.
Do not use (or ask your vet first)
- Do not stop abruptly after prolonged use without vet guidance
- Tell your vet about all other medications
When to see a veterinarian
- Vomiting blood or coffee-ground material
- Black, tarry stools
- Persistent vomiting or refusal to eat
- Lethargy or hiding
Frequently asked questions
How much omeprazole can I give my cat?
Published feline references center on about 0.75–1 mg/kg once daily. A 4 kg (9 lb) cat would be roughly 2–4 mg per day — a small fraction of a capsule. Confirm the exact plan with your vet, including how to give such a small dose.
How do you give a cat such a tiny omeprazole dose?
This is a genuine practical problem — ask your veterinarian about compounding pharmacies, which can prepare an accurate liquid or smaller capsule for cats.
How long until omeprazole works in cats?
Acid suppression begins within hours, but maximal effect builds over 3–5 days of daily dosing.
Can cats take omeprazole long-term?
Only under veterinary direction with monitoring, and stopping after long courses is usually tapered rather than abrupt.
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.