Should You Give Cats Benadryl? [And How Much Is Too Much?]


You may be familiar with Benadryl as the medication of choice for allergy symptoms. But can you give cats Benadryl? If your feline friend experiences itching or sneezing, is it safe to administer this drug without adverse reactions? This guide addresses these questions and more.

What Is Benadryl and What Is It Used For?

Benadryl is a brand name for diphenhydramine hydrochloride, a common over-the-counter medication. This drug group is used to treat symptoms of allergy and blocks histamine—a chemical released by the immune system that causes an allergic response. Its primary use is to treat allergy symptoms in people, but veterinarian professionals attest that the drug is safe to use for cats. Of course, it’s always best to consult your vet before you give cats Benadryl, which comes in tablets, capsules, liquids, and liquid gels.

Benadryl addresses symptoms by drying out runny noses and watery eyes and decreases swelling, itching, and sneezing.

Can You Give Cats Benadryl?

Even though Benadryl is not approved by the Food and Drug Administration (FDA) for use in cats, it’s widely accepted by the veterinary community as safe to provide. Giving your cat Benadryl will help treat swelling, itching, sneezing, or hives. Keep in mind, however, that this medication only treats allergy symptoms, not its cause. So you should consult your vet before dosing your cat with an antihistamine.

Note the following situations wherein you can give your cat Benadryl.

  • When Stung or Bit by an Insect

A safe amount of Benadryl for cats would prevent or minimize an allergic reaction and decrease itching. Many cat owners swear by this antihistamine drug but advise that it’s best to consult with your vet first to determine the correct dosage and severity of the allergic reaction. Not all cats display the same symptoms after being stung by an insect, and the degree of reaction depends on the cat’s immune system and the type of insect.

  • When Bitten by a Venomous Reptile

A dose of Benadryl for cats could be given for those bitten by a snake. In this case, you should immediately administer the drug—one milligram per pound of bodyweight would be the proper amount. After administering the appropriate dose, you should take your cat to the vet, where it would receive an anti-venom. (Note that anti-venoms are quite expensive, so having pet insurance would be helpful when managing the medical bill.)

  • When Itching or Scratching From Environmental or Food Allergies

Like humans, cats can be allergic to specific food proteins or grains, as well as such environmental allergens as pollen, mold, grass, and weeds. A Benadryl dose for cats would treat their allergy symptoms by quickly reducing the itching and scratching.

  • With Motion Sickness

You can also use this antihistamine medication to potentially prevent motion sickness in your cat before traveling, thereby preventing dizziness or vomiting.

  • For Calmness

Benadryl for cats will cause sedation. If you need your cat to stay calm in a stressful situation—e.g., during travel—giving them this aid will make your cat sleepy and prevent it from crying or becoming impatient or bored.

This antihistamine, however, can cause the opposite effect in cats—a phenomenon known as a paradoxical effect, manifested by extreme excitement or nervousness.

As with all medication, there are precautions that you need to take before giving Benadryl—it may not be safe for all cats. Note some following examples of when Benadryl may not be safe for cats.

  • Constant/High Levels of Anxiety: It’s not advisable to regularly sedate your cat with Benadryl to alleviate stress. Instead of continual sedation, address the problem and find its cause to treat it appropriately.
  • Heart Disease: If your cat suffers from heart disease, high blood pressure, or even glaucoma, consult your vet before giving them Benadryl.
  • Medication: If your cat is on specific medication or chronic medication therapy, consult your vet on whether it’s safe to administer Benadryl.

Benadryl for cats can cause side effects, some of which include:

  • Sleepiness
  • Agitation/excitement
  • Dry mouth
  • Urination problems
  • Drooling
  • Diarrhea
  • Vomiting

Again, talk to your vet before administering Benadryl to your cat to see if it’s safe and if it would interfere with other medication.

Did You Know? Benadryl is often combined with other medication that might be dangerous to your cat. Therefore, before purchasing the drug, read the package carefully to ensure that diphenhydramine (the active ingredient) is the only drug the product contains.

How to Give Cats Benadryl 

A Benadryl dose for cats should be given cautiously. Vets advise providing this medication in liquid form with a syringe. But there is the possibility that your cat won’t like its taste or odor. If so, you can go to a compounding pharmacy, where staff could flavor the liquid with a cat-approved taste, such as fish or chicken. Pills can also be flavored if that’s how you want to administer the drug.

Another alternative to giving cats Benadryl—especially for senior cats—is to mix it with senior cat food, which should be easier to ingest. You might also avoid certain gel capsules, as some kinds of solvents in them might be toxic or irritating to cats.

Did You Know? It will be easier to give your cat medication if you prepare them first by taking them to a quiet place, where they feel safe and comfortable. They will then be less likely to get scared, and you’ll be able to give them the medication quickly.

How Often Can You Give Cats Benadryl?

Typically, the prescribed Benadryl dosage for cats is 1mg per pound of body weight, two to three times a day. So an average cat of around 12 pounds would need to take half of a 25mg Benadryl tablet every eight to 12 hours. As with any medication, you should use Benadryl cautiously and with guidance from your vet.

What Is the Lethal Dose of Benadryl for Cats?

Administering more than the recommended dosage of Benadryl for cats may cause lethargy, dry mouth, respiratory depression, or seizures. Therefore, you should be extra careful not to give your cat a lethal dose.

Make sure you weigh your cat before giving the medication and provide only the recommended amount. Do not give more than 1mg per pound of your cat’s body weight, and never administer Benadryl more than every eight hours in a 24-hour period.

How Long Does It Take for Benadryl to Work on Cats?

Absorption of the liquid form of Benadryl has proven to be effectively quicker than a tablet. On average, after a cat has been given a Benadryl dosage, it takes about 30 minutes to an hour to start working, and the effect lasts around eight to 12 hours.

Did You Know? Benadryl side effects can last quite some time. For example, Benadryl can make cats sleepy and lethargic for about 12 hours. This short-acting medication should stop working within 24 hours, but its effects can be longer in pets with liver or kidney disease.


Benadryl is a safe and effective option to help an itchy or sneezing cat. But always double-check the Benadryl for cats dosage and monitor your cat’s reaction to the medicine. It’s best to first consult your vet before administering this drug, just like any other OTC medicine.


Is Benadryl safe for cats?

Benadryl is an antihistamine you don’t need a prescription for. And though it’s human medicine, it’s also considered safe for cats. It’s best, however, to consult your vet before you give your cats Benadryl.

Can you give cats Benadryl for allergies?

You can give your cat Benadryl to treat an allergic reaction or allergies. As in people, this medicine lessens the symptoms of food or environmental allergies in cats.

Can you give cats Benadryl for sneezing?

Can you give cats Benadryl for sneezing and other similar problems? Yes. You can also provide this drug to your cat to alleviate upper respiratory symptoms caused by allergies, as well as watery eyes, runny noses, itching, hives, and more.


When she couldn’t decide between being a nurse, a psychotherapist, and a financial genius, Ofelia decided to do all three. Her interests run far and wide, and she loves researching about everything you get to read on our website. Credit cards or top-notch software, she’s here to tell it all like it is.

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