ToolsDose calculator

How much Zyrtec, Claritin or Benadryl for my dog?

Pick the medicine, type your dog's weight, read the warning, and get a tablet count from my chart. The warning comes first, every time.

By Dr. Steve Pelton, DVM, Hearthstone Animal Clinic

Last reviewed by Dr. Steve Pelton, DVM on October 5, 2026

Dose by weight

How much can I give my dog?

Pick the medicine, tell me your dog's weight, read the warning, and you'll get the number from my chart.

1. Which medicine?

Plain ZyrtecCetirizine, 10 mg tabletsPlain ClaritinLoratadine, 10 mg tabletsPlain BenadrylDiphenhydramine, 25 mg tablets

Allegra will show up here once Dr. P signs off on its chart.

2. How much does your dog weigh?

If you enter kilograms, I convert them to pounds (1 kg is about 2.2 lb). Then the weight is rounded to the nearest whole pound and matched to the chart. Weigh your dog if you can, because a guess can land you in the wrong row.

3. Read this first. Every time.

Call your vet before giving an antihistamine if your dog:

is pregnant or nursing, or is a young puppy
has glaucoma
has heart disease or high blood pressure
has ever had a seizure
has trouble peeing, or an enlarged prostate
has thyroid, kidney or liver disease
is a senior, or takes any other medicine, including sedatives or anxiety pills

I've checked: plain tablet, one active ingredient, no -D, no xylitol.

Pick a medicine to start.

General education, not veterinary advice. If your dog is miserable, see your vet.