Question: how much diphenhydramine to give your dog?
Answer: Benadryl Dosage for Dogs The standard dosage for a dog is 1 milligram per pound of body weight, so one tablet is perfect for a 25-pound dog. Veterinarians suggest giving a dose every 8-12 hours (about 2-3 times a day). Small dogs under 25 pounds can take the children's formula of liquid Benadryl.