Giving Benadryl to your dog: should you do it? Is it helpful and harmless? Or is Benadryl for dogs dangerous and a bad idea? Used properly, in the right situations, Benadryl can be a lifesaver—preventing headaches and alleviating discomfort for your dog. You can give them 1mg of benadryl per pound your dog weighs three times per day. Sunday 2019-03-03 13:10:35 pm | How Much Benadryl Can A 20 Pound Dog Have Free Download PDF Video provide in-home dog training and puppy training, Boost Your Dog's Intelligence, Eliminate Bad Behavior And Create a Loving Obedient Pet. Dog Training: Sunday 2019-03-03 13:10:35 pm how much benadryl can a 20 pound dog have. BY How Much Benadryl Can A 20 Pound Dog Have in Articles. How Much. 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. 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. The dose of Benedryl for dogs is 1 mg per pound that your dog weighs so a 20 lb dog would get 20 mg. This can be repeated two to three times per day. You can use this table as an instrument to see how much Benadryl (Diphenhydramine) you can give your dog. You should administer this dosage every 8 hours/3 times a day. You should administer this dosage every 8 hours/3 times a day. The dosage is 1/2 - 2 mg. per pound of body weight every 8 hours,so you could safely give the dog one 25 mg. tablet or capsule. This is for Benadryl in the US. If you're in the UK or elsewhere ,Benadryl contains a different ingredient and you cannot give it to dogs. This is important information in determining how much Benadryl can I give my dog, or if you can give it at all. This is especially true if you have an older dog that is taking other medications. Your vet will advise you on the correct dosage, as this may vary due to interaction with other medications and other factors. Give 1mg of Benadryl per pound such that if your dog weighs 30pounds, you should give it 30 mg of Benadryl. Administer themedicine three times in a day Talk your veterinarian - while.