Benadryl Dosage for Cats Calculator
Cats can take diphenhydramine when a vet recommends it. The reference range published for cats is 2–4 mg/kg every 8–12 hours, but cats are small, so the practical dose is usually a fraction of an adult tablet.
Enter your cat's weight to see the published reference range. Used for mild allergic reactions, insect stings and occasionally travel.
How "mg per kg" dosing works
Cats also hate the taste: the liquid often causes heavy drooling or foaming. Ask your vet for the right form and dose before giving it.
Vets dose by body weight because the same amount of drug is spread through a bigger or smaller body. Drag the weight to see how the reference range and the number of tablets move together, and why a tablet sized for a 70 kg adult human can be a big dose for a small pet.
Range 9.1–18.1 mg = 0.75–1.5 tablets of Children's chewable, 12.5 mg. For comparison, a typical adult human dose is based on about 70 kg.
Warnings before giving Benadryl
- Never give a combination cold or sinus product: cats are extremely sensitive to acetaminophen and decongestants.
- The bitter taste can make cats foam at the mouth. That is usually harmless but upsetting; ask your vet about a compounded, flavoured version.
- Some cats become excited rather than sleepy after diphenhydramine.
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Questions owners ask
Can cats have Benadryl?
Yes, vets do use diphenhydramine in cats, but only plain diphenhydramine and only at a vet-approved dose. The published range is 2–4 mg/kg; for a 10 lb (4.5 kg) cat that is roughly 9–18 mg.
Why is my cat foaming after Benadryl?
Diphenhydramine tastes very bitter. Foaming or drooling right after dosing is a taste reaction. If your cat also seems agitated, wobbly or breathes fast, call your vet.
Will Benadryl calm my cat for travel?
It makes some cats drowsy and others hyper, so results are unpredictable. Your vet can prescribe medicines made for travel stress in cats.