How Much Benadryl Tablet For A 25lb Dog?

Benadryl contains Diphenhydramine which is a antihistamine and used to treat allergy. Benadryl is for human use and FDA has not approved for animal use. But vet can prescribe this drug as extra label drug. Its dose in dogs is 1-4 mg per Kg body weigh or 0.5 to 2 mg per lb body weight,  2-3 times a day. As your dog is 25 lb, so you can give 12.5 to 50 mg benadryl. Remember, don't use any medicine without vet supervision.