Benadryl for Dogs

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Is Benadryl an option to treat your itchy dog?

You spend $$$ at the vet, and then it hits you: Why don't I try Benadryl?


However, while some (not all) Benadryl formulations are safe for some (not all) dogs, the results are often disappointing.

A dog owner considering giving their dog Benadryl should only do so after checking the active ingredients and speaking to your vet. This is because some Benadryl formulations contain drugs that are unsafe for dogs, and some health conditions make the use of Benadryl undesirable.

Also, if you're expecting Benadryl to be a miracle alternative to those costly prescription products then prepare for disappointment. Sadly, antihistamines are not nearly as effective in dogs as they are in people. And, last but not least, Benadryl is not FDA licensed for animals. This means there are no official safety trials of the drug in dogs, and giving it is at your own risk.

Benadryl Options

Look beyond the box and read what the active ingredients are. Benadryl is the trade name for the generic antihistamine, diphenhydramine. However, just because it says Benadryl on the box doesn't mean it's just diphenhydramine inside.

Benadryl US and Benadryl UK contain different medications (Diphenhydramine in the US but Acrivastine in the UK.) While quite a lot is known about the safety of diphenhydramine, information on acrivastine in dogs is limited and its use, therefore, should be avoided.

Another consideration is to check for additional ingredients such as xylitol (in Benadryl no-sugar syrups) or decongestants such as pseudoepinephrine. Both xylitol and pseudoepinephrine are potentially dangerous to dogs and should not be given. Thus, only consider giving Benadryl if it contains diphenhydramine and nothing else.

Benadryl Benefits

Diphenhydramine is an antihistamine. This group of medications is extremely helpful to people with allergies such as hay fever. An antihistamine does what it says on the label, it suppresses the production of histamine, which forms part of the allergic reaction.

It is histamine that causes a lot of the unpleasant symptoms of an allergy, such as a runny nose, sneezing, and itchiness. So with histamine crossed off the list, those symptoms subside.


Allergies are common in dogs, resulting in an irresistible itch and desirable to lick themselves sore. However, the action of Benadryl in dogs is often disappointing, plus it may make the dog drowsy.

Veterinary dermatologists suggest antihistamines do have a role in itch management, but when given in addition to existing treatments, rather than instead of. The best hope is to reduce the dose of those other medications, rather than knock out the itch altogether.

Benadryl Dose

Only consider giving Benadryl if your dog is fit and well. Certain drugs are not compatible with Benadryl, so always speak to your vet before dosing. In addition, dogs with glaucoma, high blood pressure, or urinary incontinence should not be given Benadryl.

For those dogs that get the green light, the dose is 1 to 4 mg/kg by mouth, two or three times a day. Most capsules are 25 mg, which means an average sized Labrador would take two capsules in one dose.

The Benadryl Bottom Line

For a healthy dog, there's little to be lost by giving Benadryl a go, but don't get your hopes too high. At best, it may play a role in reducing the dosages of prescription meds that control your dog's itch.

However, don't despair if your dog is itchy. There are lots of things you can do to help, such as bathing the dog, giving nutritional supplements, and reducing exposure to allergens. And if things get really intense, there are some great prescription meds that reduce itch but with minimal sides effects. Ask your vet for more details.