How Much Benadryl Can You Give A Cat?

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Any cat parents know that there are times their feline children get a bad allergy. Sometimes allergy symptoms are so mild that they can be neglected and left there to disappear on their own. But sometimes they are more noticeable and prolong cats’ suffering. In this case, cat owners often think of Benadryl as a common solution to allergy and itchiness. Maybe you’re one of them.

But medical administration to pets is not simple. There are so many questions to ask. Benadryl has been confirmed safe to give to cats, but the dose is very different from dogs. How does Benadryl work? How much Benadryl can you give a cat? How can you give the drug to cats? This article gives you exactly the answers you’ve been looking for.

What Benadryl Does For Cats?

Benadryl is currently most used in cats for following purposes: allergies, bug bites, bug stings, rashes, skin reactions, motion sickness (in this case, Benadryl is used as a slight sedative to help cats fight car sickness or sea sickness in long trips), nasal congestion, vaccine reactions.

However, you should keep in mind that Benadryl simply suppresses the symptoms. It is not intended to deal with the root causes of those symptoms.

How Does Benadryl Work?

When allergy or inflammation takes place, a chemical called Histamine is produced by the body. The chemical then makes a thorough trip through the body in search of histamine receptors. When it finds the right receptors, it attaches itself to them. At this point, histamine becomes the culprit behind swelling, itchiness as well as other symptoms typically associated with allergies.

Histamine receptors come in two different kinds: H1 and H2. The H1 receptors can cause problems for small blood vessels, smooth muscles. Once histamine connects with H1 receptors, small blood vessels expand. Fluid also starts leaking out. This is the beginning of tissue swelling as well as itchiness. Symptoms such as difficulty in breathing and tightness are a result of the constriction of smooth muscles that line small airways.

When histamine connects with H2 receptors, the heart starts to beat faster and an increase in stomach acid production can also be seen. This process heightens ulcer risks.

Antihistamine is the name used for drugs which act to prevent histamine from exerting an influence. Some antihistamines work better for the relief of allergies, and others work better for treating stomach acid. There are different antihistamines, depending on whether the histamine attaches to H1 or H2 receptors. Not many drugs on the market can treat both kinds of attachment well.

Diphenhydramine (Benadryl) is especially effective for reducing effects on health when histamine connects with H1 receptors. It’s why Benadryl is often used for the relief of swelling or itchiness.

When Can You Give Benadryl To A Cat?

Under no circumstances should you administer your pets any drugs without consulting your vet in advance. You do not just go to the store, buy anything with the name tag Benadryl and give it to your beloved feline friend at home. There are a few different kinds of Benadryl on the market. They have different active ingredients. If you don’t do some research and consult professionals first, you may end up giving your cat fatal chemicals.

Although this drug is considered to be somewhat safe, it has side effects, which we will discuss later in this article, reactions when mixed with other substances and can easily be overdosed. If your four-legged friend is suffering from heart problems or prostate problems or is carrying a child, this drug should not be administered to them. The bottom line is, always consult your vet first.

How Much Benadryl Can You Give A Cat?

Benadryl is sold in the form of tablet, drinking liquid and injectable. The tablet form and the drinking liquid form are administered orally (PO). The injectable form is administered by something called the intramuscular method (IM). IM means you give your cat injections deep through the muscles.

Tablets are available in the form of 12.5 mg per pill, 25 mg and 50 mg. For drinking liquid, there is one popular size of 12.5 mg per 5 ml. The injectable form comes with 50 mg per milliliter.

For cats only, if you give this drug via the PO (oral) method, you need exactly 0.25 mg to 0.5 mg per body pound every 12 hours. So, if your cat weighs 10 pounds, you need to give it a dose between 2.5 mg and 5 mg. For a cat in the average weight range nowadays, a dose equaling half of a 25 mg tablet would do. Consult your vet for more details based on your cat’s specific conditions. In case you want to opt for the IM (injection) method, you need to give your cat 0.5 mg to 1 mg per body pound.

The standard time between 2 administrations is 12 hours. That means you may have to feed your cat this drug twice a day. For how long you should give your cat the drug is based on specific health issues in question. If you have a prescription from your qualified vet, follow it and do not stop until you’ve done everything the prescription says. A sudden halt may result in recurring symptoms.

How To Give Benadryl To A Cat?


By:Amy Mc67 

You have probably seen many people giving drugs to their cats using syringes. This is a relatively fast way to administer drugs. It is also safe because you don’t have to mix drugs with food or anything else. The problem is, not all cats can stay calm in the presence of a syringe. Bad experiences of syringe may scare your cat away from drugs for a long time. If you do not know how to administer drugs in this way, read the next method.

Flavor The Drug

This is something you should not do at home. You can go to a compounding pharmacy and ask if the professionals there can flavor your liquid or tablets with tastes that cats love, for example, chicken, turkey, fish, etc.

Mix With Food

Consult your vet to see what kinds of food you can mix this drug with. It should not be very difficult. But your vet will be able to tell if there is any harmful combination to avoid.

Side Effects Of Benadryl To Cats

Expect these side effects when you give your cat Benadryl:

  • Cat may get unusually agitated (hyperexcitability).
  • Cat may urinate less.
  • Cat may experience sedation.
  • Cat’s mouth may get dry.
  • Cat may vomit unusually.
  • Cat may get diarrhea.
  • Cat may lose appetite.


We have answered thoroughly the most important question when it comes to Benadryl administration. How much Benadryl can you give a cat depends on your cat’s body weight. The instruction can’t be any clearer. But you have to consult your vet first to ensure the best safety for your cat.

Feel free to ask us any questions by leaving your comment below. If you like our post, don’t hesitate to share it. Thank you for reading and have a nice day!

A NOTE TO ALL OUR VISITORS: The information provided on this site is intended for your general knowledge only and is not a substitute for professional medical advice or treatment for specific medical conditions. You should not use this information to diagnose or treat a health problem or disease without consulting with a qualified healthcare provider. Always seek the advice of your veterinarian or other qualified health care provider with any questions you may have regarding a medical condition. *Never disregard medical advice or delay in seeking it because of something you have read on the petful101.com site.

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