Can You Give Cats Benadryl®?

Updated May 6, 2024
A cat scratches themselves in a field of grass.

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Perhaps at some point, your veterinarian has recommended Benadryl® for one of your pets. Maybe you’ve heard of someone using it for their pet, and you’re wondering if you can safely give it to your cat to make her a little sleepy before her next vet trip.

Benadryl is a name-brand medication whose primary active ingredient is diphenhydramine, an antihistamine. Although it is not specifically labeled for use in pets, it’s commonly recommended and used by veterinarians “off label.”

Here’s what you need to know about giving cats Benadryl.

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Can You Give Cats Benadryl®?

For a healthy adult cat, diphenhydramine is considered safe to use but should only be given under the direction of your veterinarian.

Benadryl for cats should never be administered without specific diagnostic and dosing advice from your vet.

What Is Benadryl® Used For?

The antihistamine diphenhydramine is used to treat acute allergic reactions (such as bee stings), for which it is very effective to resolve the swelling.

However, it’s also prescribed for chronic allergies—although Benadryl® does not work well in all cats, and some trial and error might be needed to find which antihistamine works best for your cat.

Benadryl® can also be used to help reduce the severity of motion sickness or to provide minor sedation. It may help some cats who are vomiting as well.

Benadryl® Dosage for Cats

Most veterinarians will dose Benadryl® for cats using a combination of recommended doses and practical experience, since it is not labeled for use in cats. Always chat with your vet to ensure the correct dosage of Benadryl will be given to your cat. Factors such as health, weight, and age will need to be considered.

Benadryl® can be given orally or as an injection in veterinary hospitals. Quite a few oral formulations are available, so you need to consult with your veterinarian if you are considering Benadryl® for your cat.

Many over-the-counter options made for people have additional medications added or are extended-release formulas, both of which should be avoided.

Tablets that are not scored should never be split or broken for administration, as the medication may not be evenly distributed, and an accidental over- or under-dosing can occur.

Is Benadryl® Safe for Cats?

Benadryl® is generally considered safe for healthy, adult cats.

However, it should only be administered under the direct supervision of your veterinarian and at the dosage your vet recommends.

Cats that should not be given diphenhydramine include:

In most cases, severe symptoms (such as anaphylaxis) should not be treated at home with diphenhydramine without immediately seeing the vet.

Even milder signs, such as itching or sneezing, should be diagnosed before diphenhydramine is administered. Giving this medication can mask symptoms that are helpful to your veterinarian in making an accurate diagnosis.

Benadryl® for Cats Side Effects

Although vets do consider diphenhydramine safe to use for cats, there are several possible side effects:

If your cat experiences any of the above symptoms, contact your vet immediately.

Because of the significant number of side effects seen with diphenhydramine, in most cases, it is appropriate only on a short-term basis.

Keep in mind that your veterinarian may have different recommendations for your pet’s individual situation.

Is Benadryl® the Best Medication for Cat Allergies?

Although diphenhydramine is sometimes used to treat chronic environmental allergies in cats, antihistamine use in cats can be very hit or miss. While some patients will see a reduction in allergies when diphenhydramine is used, most do not.

If a cat doesn’t respond to one antihistamine (such as diphenhydramine), they may respond to a different one. Because of this, it may be necessary to try several different medications to find one that works.

Typically, antihistamines are not a first-line treatment for cats with environmental allergies, and they are never used to treat other allergies, such as food allergies.

It’s important to have your cat tested, determine what they are allergic to, and then have your vet tailor the right treatment for your pet.

For example, flea allergies are best treated with appropriate flea control, while food allergies are treated with diet trials. 

Skin allergies in cats may be treated with allergy injections, steroids, or immune-mediating medications.

Respiratory allergies (with symptoms such as runny nose and eyes as well as sneezing) are very rare in cats.

Most cats with these signs have a respiratory infection and are not generally treated with antihistamines. Because of this, don’t assume your cat has allergies if you see these signs or try to treat them at home with human allergy medications.

If your vet is recommending diphenhydramine, it’s most likely to treat an allergic reaction to something like a bee sting or to help combat motion sickness.

Sandra C. Mitchell, DVM, DABVP


Sandra C. Mitchell, DVM, DABVP


Sandra Mitchell is a 1995 graduate of the New York State College of Veterinary Medicine. Since graduation, she has worked in many fields...

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