Can you Give Your Cat Benadryl?

Picture of a cute cat

Are cats allergic to Benadryl or could you give this medication to your cat in case she has an allergy? We’ve written about whether you can give Benadryl to your dog before, but in today’s article, we’ll look at whether it makes a good option for cats.

A Word about Human Medication

It’s generally a good idea to avoid giving your pets medication that’s originally intended for humans. If you don’t have a talk with your vet or even do a bit of research online, you might not know whether you risk making your furry friend go through a life-threatening episode.

We’re all well-intended when trying to treat pet health issues at home, but sometimes, it pays off to be informed and learn more about various medications and whether they are safe to use on animals.

Can You Give Your Cat Benadryl?

The short answer to this question is yes. In fact, some vets use it in therapy, as well. The dosage, however, needs to be the correct one in order to prevent adverse effects from happening. Diphenhydramine, the active ingredient in Benadryl, is usually safe for animals and it can be administered orally in different forms (crushed, pills, or liquid).

There are vets that recommend giving one milligram Benadryl per pound of body weight, but calculating the concentration can be challenging. So, for a cat that weighs in at 10 pounds, you can use 4 ml of a 12.5mg/5ml concentration, or you can give her approximately half of a 25mg tablet.

The dosage depends on other factors, not just the pet’s weight. For example, other things that matter are the cat’s age, whether she has any other medical conditions for which she receives medication, whether she has any allergies, and a variety of other things. Usually, it’s a better idea to ask your vet if you are allowed to use Benadryl with your specific feline companion.

It’s also worth noting that the effects of one dose of Benadryl can last for as many as eight to twelve hours, which can obviously make a responsible cat parent get a little panicky.

What Can Benadryl Be Used For?

You’ll be surprised by the variety of problems that Benadryl can fix or at least improve the symptoms of. Let’s have a look at each and every one.


Allergies in cats can be developed spontaneously. If your cat is allergic to your deodorizer, houseplant, perfume, or household cleaner, she might not be able to breathe properly. Removing the allergen sometimes doesn’t fix the problem or it could take a couple of days for the allergy symptoms to go away.

Also, cats might have sensitive skin and develop redness or inflammation as a result of being allergic to plastic bowls, detergent, woolen bedding, or even some types of toys (such as those made of latex). Benadryl can make all of the clinical signs of a cat allergy milder.

Reactions to vaccines

There are many cats that are likely to have an allergic reaction to vaccinations. That’s why some vets give Benadryl to a cat even before they give her the shot. Even if your cat has never had an allergic response to a vaccine before, that doesn’t eliminate the possibility that it happens in the future.

Manufacturers use different additives and preservatives in their biological products, and if you switch from one to another without even realizing it, your cat could be allergic to the new one.

Motion sickness

If you intend to take your cat on a trip in your car, think again. Many cats experience motion sickness, so they can get quite nauseated when they are in a car or even on a train. Benadryl can help a cat relax a little, but if you’re looking to prevent nausea and vomiting episodes, you should probably choose a different medication.

Anxiety or stress

Since Benadryl is a mild sedative, it can prove its worth under some circumstances. For example, if the cat is going to be confined to a small space for some time (such as you going to the vet and keeping your feline buddy in a carrier), you could give your pet a small amount of Benadryl. At least she’s not going to be stressed out, and she might even take a nap. Just make sure you don’t overdo it with the dosage, especially in these cases.

Bug bites

Lots of insects can bother a cat, but fleas are the most horrible of all as they make her itchy and uncomfortable. Plus, if you didn’t know, some cats are actually allergic to flea bites. Benadryl can at least help the cat scratch less, therefore minimizing the amount of aggression from which her skin would suffer.

When You Shouldn’t Use Benadryl

If your cat receives medication for some other kind of health problem, avoid using Benadryl as it might either interfere with that drug’s action or cause serious side effects. Here’s a list of medications that it interferes with:

  • Amitraz
  • Epinephrine
  • Selegiline
  • Furazolidone
  • Warfarin
  • Heparin
  • CNC depressants (usually given to cats who have anxiety)

If your cat has been bitten by a snake, scorpion, or any other type of insect/animal, don’t just give her Benadryl because it won’t fix the problem. She needs to be taken to a vet right away, instead. If your cat is known for having loose stools or she has problems with her digestion, in general, avoid giving her this medication as it could cause diarrhea episodes.

Side Effects

Here are some potential adverse reactions that you could see in your cat if you’ve given her Benadryl.

  • Disorientation
  • Nausea or vomiting
  • Hyperexcitability
  • Loss of appetite
  • Diarrhea
  • Lowered urination frequency and quantity
  • Dry mouth


It would certainly be a good idea to have Benadryl in your home in case you do need to give it to your cat at one point or the other. However, as is the case with many other types of medications primarily intended for people, Benadryl shouldn’t be given to cats in excess, too often, or while the cat is under treatment with other types of drugs.

Last, but not least, we have to note that Benadryl only solves the symptoms of an issue. This means that if the cat is allergic to something, she will still have an allergy if the allergen does not disappear from her living environment. Find the cause and eliminate it, if you can.

Benadryl is a somewhat safe method of sedation, but you shouldn’t overdo it. Plus, be prepared to witness your cat being dizzy and confused for a period of eight to fourteen hours. Measure every dose carefully when giving this medication to your feline friend.



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