Can I give my dog Benadryl?

Updated 24/04/2024

If you’re from State-side USA or Canada, Benadryl is a widely recognized brand of over-the-counter medicine. For the rest of us, it’s a human antihistamine that comes in the form of a pill, a liquid, or a spray. But, what about our pooch pals? When Spring arrives and your snuffle-bear starts sneezing, could this be a quick fix for them? Can dogs have Benadryl?

Dogs should never be given any type of medicine (for humans or doggos) without consulting your vet first. Never try to help your dog with something that has not been veterinary prescribed. We know Amazon can have some great deals on dog allergy treatments, but just isn’t worth the risk to your pup.

Okay, so with that all in order, let’s answer the question of ‘Can I give my dog Benadryl’ and other tips on allergy medicine for dogs.

What is Benadryl?

We think the American Kennel Club worded the answer to this best on their website…

“Benadryl is the brand name for the active ingredient diphenhydramine HCl. Diphenhydramine is a first-generation ethanolamine-derivative antihistamine.”

Couldn’t have said it better ourselves! Basically, it’s an antihistamine used to reduce the symptoms of itching, swelling, and sneezing for mild to moderate allergies and hive outbreaks. It was designed and tested for humans, so is there a Benadryl dosage for dogs?

Can I give my dog Benadryl?

There’s no clear ‘yes’ or ‘no’ to this answer, why? Because it’ll be up to your vet to decide whether to use Benadryl for dogs. In America, Benadryl is not certified as a vet treatment for pup allergies, however, this doesn’t mean they can’t prescribe it for them.

Depending on your dog, a small dosage of Benadryl can help if your fur baby is suffering from an allergic reaction. Vets may recommend about 0.9 to 1.8 milligrams per pound of your pup’s body weight, but it will hugely depend on the form of Benadryl you choose. Liquid Benadryl will enter your dog’s bloodstream a lot quicker but it is much more concentrated than the tablets - small dogs weighing less than 10 pounds can be given no more than 2ml of liquid Benadryl.

Like many antihistamines for humans, Benadryl can have a sedative effect on your pooch. If your vet is comfortable with you giving your pupper Benadryl, make sure their first dosage is with children’s Benadryl. This is not as strong as the adult form and will be gentler on their tummy.

For some pooches who suffer from bad motion sickness, Benadryl may also be suggested as a way to help them through those bumpy car rides.

It is worth noting that some formulations of Benadryl in the UK contain a sugar alternative such as Xylitol, which is toxic to pets including dogs so these formulations should not be used as they are unsafe. Some forms of Benadryl worldwide also contain sodium and/or alcohol, so these should also be avoided due to toxic effects (especially in smaller dogs in which the consequences could be significant and dangerous). 

Can I give my dog Benadryl for allergies?

There are a few different ways to help a dog with allergies, and your vet may suggest Benadryl is one of them. So long as you give them the correct dosage recommended or prescribed by your vet, you don’t notice their symptoms worsening, and they aren’t suffering from any other illnesses, this human antihistamine can be effective on allergies like hayfever in dogs, fleas, and dust mite allergies, and other skin allergy reactions. Sometimes, depending on the severity of allergy symptoms, antihistamines are not the most appropriate medication to treat the problem. If your pup's breathing is either increasingly rapid, indeed labored, or hindered by swelling caused by the allergic reaction, it’s important that you contact your vet as an emergency where appropriate emergency intervention can be implemented. 

How much Benadryl can I give my dog?

The recommended Benadryl dosage for dogs will be dependent on what your vet says. Their age, breed, medical history, and stomach sensitivity will all factor in how much, if any, they can take. As mentioned above, small dogs are far more susceptible to Benadryl side effects and will need the very smallest dosage possible. Giving too much of the drug can cause toxic effects ranging from excessive sleepiness (which could hinder your dog's breathing leading to respiratory distress) to kidney and liver damage. So, it’s important that you only use medication that is advised by your veterinarian, at a particular dose for your dog’s size and breed, and takes into account their current medical status. Using medicines without appropriate, qualified, medical guidance is strongly not recommended. 

How often can I give my dog Benadryl?

If your vet has given you the green light to give your dog Benadryl, they will suggest about one or two dosages a day. Benadryl can take up to and over an hour to take effect, so never try to give your dog more if you don’t think the medicine is working. Again, contact your vet if you’re worried their allergic reaction isn’t going away or is becoming worse.

Can I give my dog Benadryl for pain?

While Benadryl can have a sedative effect it is not a painkiller. If your pup is suffering from an injury or illness, never attempt a homemade remedy or human medicine. Always take them straight to the vet if they are in pain or you think they may be hurt.

Can I give my dog Benadryl for itching?

Itching can be a symptom of a dog having an allergic reaction, so as long as you’ve asked your vet if your dog can take Benadryl (and how much), this can help relieve itching. However, excessive scratching, hives, or dry skin may not be a sign of an allergy but of something else. If you’re ever in doubt, always contact their vet immediately.

Meet our veterinary expert, Lily

This article has been checked by veterinarian Lily Richards BSc (Hons) BVSc MRCVS. Lily qualified from Liverpool University in 2011 and spent 5 years as a veterinarian working in mixed animal practice. As Lily’s passion for exotics and exploring more complicated small animal medical cases developed, she stepped into small animal-only practice. By 2018 Lily was leading a busy branch of a large hospital practice with a fantastic team, enjoying working on both surgical and medical cases. Since falling poorly in 2021 Lily has found a new passion in medical writing. Sharing medical knowledge and writing for the public is a particular passion.

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