Abiding by the one mg/pound dose, one 25 mg tablet would be the correct dose for a 25-pound dog. The dose can be repeated twice in the day. The dose can be repeated twice in the day. Benadryl, also known by its common name diphenhydramine, is an antihistamine. So a 35-pound dog should get 35 mg of Benadryl per dose. The Benadryl dose for 16 lb dog would be 16mg. Ask your vet for more help with dosing frequency, but the typical dose is 3 times a day, every 8 hours apart. How much LIQUID children's Benedryl can I give my dog per pound? Every article I've found tells you for millilgrams for giving tablets but I've yet to find an answer telling me how much MILLILITERS of the LIQUID to give a dog per pound of body weight. My 8 month old puppy gets car sick. One of my friends told me that they give their dog Benadryl so they sleep during the trip. They said their vet told them to give 1/2 tablet for every 25 lbs. How much Benadryl should I give? The standard dosage for oral Benadryl is 1 mg per pound of body weight, given 2-3 times a day. Most drug store diphenhydramine tablets are 25 mg, which is the size used for a 25 pound dog. Call a vet. Don't risk poisoning your animal. How much benadryl can you give a 40 pound dog for itching? - Answered by a verified Dog Specialist - Answered by a verified Dog Specialist We use cookies to give you the best possible experience on our website. My 8 month old puppy gets car sick. One of my friends told me that they give their dog Benadryl so they sleep during the trip. They said their vet told them to give 1/2 tablet for every 25 lbs. You shouldn't give benadryl to a pup that small. I was instructed to give my (45 pound) dog a half of a children's tab when he's stung by a bee. I don't think you could even cut up a children's benadryl enough for it to be safe. You can always call a vet, but you wouldn't want to risk your dog overdosing. Benadryl dosage for dogs - I've heard that you can give benadryl to a dog, so how much should I give to my dog with allergies - weighs around 25 lbs.