Is Benadryl® Safe for Cats and Dogs?

Dog and owner at home
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Benadryl® (also known as Diphenhydramine Hydrochloride)is the registered trademark of Pfizer. The non-trade name of this antihistamine drug is Diphenhydramine Hydrochloride (HCl)1. Benadryl® is the most commonly recognized trade name of this drug (in the US). There are other antihistamines available and on the market. Speak to your veterinarian or human physician about what antihistamine is right for your pet should he or she need one. 

Allergic Reactions

Like humans, dogs and cats get bitten and stung by insects, especially in the warmer months. This may yield little effect, or it could be an emergency situation, depending on the venom, the pet's allergic reaction, and the location of the bite, as swelling in the neck and throat region could cause severe difficulty breathing. Dogs most commonly have swelling of the face and muzzle from snapping at insects with their mouth; cats more often suffer from swollen paws from batting at insects.

What to Watch For

After the initial pain from the sting or bite, the allergic swelling that results isn't too painful. It is usually sudden, dramatic, and itchy. Conversely, infections (i.e. bacterial) typically are painful. The swelling needs to be monitored closely to make sure the animal can breathe and eat properly and that the skin isn't too "tight," eventually suffering cell death (necrosis) and secondary infection. If spiders are a concern in your location, please check with local health officials to learn what the signs and symptoms could be for spiders in your location.

Using Benadryl®

Benadryl® is a great emergency drug for allergic reactions related to insect bites and stings. Relatively safe, it can be used in most pets, children, and adults to calm the allergic reaction and possibly avert an emergency situation due to extreme swelling. Using caution is advised for pregnant and nursing animals. The most commonly seen side effect is drowsiness.

Drug Cautions

While a fairly safe drug, Benadryl® does have potential adverse effects; it's not for every pet and should be used with extreme caution in patients with glaucoma, prostatic disease, cardiovascular disease, and hyperthyroid, among other conditions.

This class of drug may also interact with other medications that your pet is taking, so be sure to discuss the use of any drugs for your pet with your vet first.

Be Prepared

Speak to your veterinarian to determine if Benadryl® is a drug that would be appropriate for your pet should the need arise (i.e. while camping). If so, your veterinarian should be able to give you an idea of safe dosage range based on the weight, age, and condition of your pet.

Reference 1Diphenhydramine HCl/Benadryl® reference: Veterinary Drug Handbook, 3rd. Edition, Donald C. Plumb, pp 248-250

Please note: This article has been provided for informational purposes only. If your pet is showing any signs of illness, please consult a veterinarian as quickly as possible.