Cat Benadryl Dosage Calculator

Read this first

Before anything else, talk to your vet before giving your cat Benadryl. Cats are small and sensitive, so getting this right matters even more than it does with dogs, and a vet should sign off on the dose first. Use only plain diphenhydramine, with that as the single active ingredient, and never a combination cold or allergy medicine, since the decongestants and pain relievers in those can be deadly to cats. This tool is a reference for that conversation, not a reason to medicate on your own.

What this does

So your vet has mentioned Benadryl for your cat, or you want to understand the dosing first. This estimates a diphenhydramine dose from your cat's weight, and shows it in milligrams, as a liquid amount, and as a count of tablets and children's chewables. Treat it as a sanity check to bring to your vet, not a prescription.

How to use it

1. Enter your cat's weight, and pick the unit.
2. Choose the dosage unit and the liquid unit you want.
3. Tap Calculate to see the dose, the liquid amount, and the tablet counts.

Because cats are small, accuracy is important, so enter the weight in pounds and check everything with your vet.

How it works

The guideline vets reference for diphenhydramine is about 1 mg per pound of body weight. So the core sum is:

dose (mg) = body weight in pounds × 1

So a 10 pound cat works out at about 10 mg. The tool then shows that as a liquid amount, since children's liquid is 2.5 mg per millilitre, and as a number of 25 mg tablets or 12.5 mg children's chewables, which usually means a part tablet for a cat. With small animals especially, the exact dose and the product really need a vet's input first. It all runs on your device.

Safety, the part that matters most

The key points are simple but important. Use only plain diphenhydramine, never a combination product, because the extra ingredients in cold and flu medicines can poison a cat. Watch out for liquids that contain xylitol or alcohol, which are harmful. Because cats are small, the right dose is a small amount, and it is easy to give too much, which is another reason to let your vet confirm it. Some cats should not have it at all, including those that are very young, elderly, pregnant, or have other health conditions, or take other medicines. If your cat shows any sign of an overdose, such as agitation, a racing heart, unusual drowsiness, or tremors, contact your vet or a poison line right away.

Questions people ask

References

1. VCA Animal Hospitals. Diphenhydramine. https://vcahospitals.com/know-your-pet/diphenhydramine
2. Preventive Vet. How to Calculate Benadryl Doses for Your Dog or Cat. https://www.preventivevet.com/pet-antihistamine-diphenhydramine-dosage-calculator