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Benadryl for Cats: Does It Work?

Cats are curious creatures, and although this trait is not as fatal as that oft-repeated quote implies, it can still lead to some undesirable outcomes - such as allergies. As a cat person, you should be more than familiar with the various potential causes of an allergic reaction in domesticated felines and what you need to do if your cat’s curiosity gives her allergies and kills her fun. Should you give your cat Benadryl? Read on to learn more.  

Benadryl and Your Cat

Benadryl is one of a number of human medications that can be safely given to pets, with the appropriate supervision of a vet. As with humans, administering the correct dosage is important, as well as knowing what possible side effects to watch out for and when you should not give Benadryl for allergies in cats. 

Because Benadryl is an over-the-counter medication and it treats one of the most common human ailments, this medicine is often a standard - and even an essential - item in first-aid kits and medicine cabinets. They are available in liquid form, as liquid gels, capsules, and tablets. 

Medically known as diphenhydramine hydrochloride, Benadryl is classified as an antihistamine - which simply means “anti-allergies.” The medicine works by blocking histamine receptors, so that even when histamine is produced in response to an allergen, the appearance of the usual symptoms does not occur. 

Benadryl works as effectively in cats as it does in humans when used appropriately. Remember, however, that while you may not experience adverse reactions when you use Benadryl, the same may not be the case with your cat. So you should consult your vet before giving kitty some Benadryl to relieve her allergy symptoms, especially if it’ll be her first time taking it. 

Another thing you should take note of is that some brands combine diphenhydramine with other ingredients, some of which could be harmful to kitty. So always check the package information to make sure your Benadryl only contains diphenhydramine. 

When given to cats, Benadryl helps provide relief from itchy and watery eyes, runny or stuffy nose, sneezing, itchy skin, swelling, and other allergy symptoms. 

When Should You Give Your Cat Benadryl?

Benadryl for cats can actually do more than just remedy symptoms of allergies; because it causes drowsiness, it is also oftentimes used as a mild sedative to relieve anxiety and motion sickness. Your vet may prescribe Benadryl for kitty to address any of the following:

  • Skin itchiness from a food allergy, environmental allergy, or dermatitis from bug bites such as fleas. 
  • A sting from a bee or scorpion, or an insect bite.
  • A bite from a snake or some other venomous reptile. 
  • A known allergic reaction to a vaccine.
  • Motion sickness.
  • Anxiety or restlessness, such as from travel.
  • Cat cold.

Pet owners should definitely include Benadryl in their pet’s first-aid kit, whether or not their cat has any known allergies or even if  they don’t travel with kitty. It’s better to have it and not need it, than need it and not have it. 

Having Benadryl in your emergency arsenal should not make you feel less worried about the risk of your feline companion developing an allergic reaction. Some cats can react more severely than others to bites or food or environmental allergens; cat breeds that are characterized as brachycephalic, for example, have naturally compromised airways as a result of their short nose and often experience serious breathing difficulties when an allergic reaction causes their airway to constrict further. 

Giving your brachycephalic cat an antihistamine may not be enough, and you will have to bring her to the vet immediately. Cat breeds with a smushed face include Persians and Himalayans.   

Allergy Symptoms

If kitty has any of the following, chances are high that she is suffering from an allergic reaction. It’s important to determine the exact cause of her allergy, if it’s her first time showing these symptoms, so that you can prevent or reduce the risk of recurrence. Always keep an eye out for the following signs so you can give kitty timely and appropriate treatment. 

  • Sneezing
  • Wheezing
  • Coughing
  • Itchy and irritated skin
  • Red and itchy eyes
  • An ear infection
  • Swelling, particularly in the paws
  • Snoring
  • Diarrhea and vomiting

How Much Benadryl Should You Give Your Cat?

Veterinarians usually recommend 1 milligram of Benadryl per pound of body weight, two to three times a day. While it is easy enough to make the calculation yourself, always consult with your vet regarding dosage and for how long kitty needs to take Benadryl - especially if it’s her first time receiving the medicine. Bigger and older cats that weigh 12.5 pounds or more can be given Benadryl tabs or capsules; kittens and cats that weigh less than 12.5 pounds should be given liquid Benadryl for children for a more accurate dose measurement. 

Benadryl is relatively safe, but some cats may still develop an adverse reaction to the drug or suffer from an overdose. Symptoms of an overdose include dry mouth, excessive lethargy, respiratory problems, seizures, or coma and require an emergency trip to the vet. 

Other side effects of Benadryl that may be cause for concern and cessation of use of the drug include urinary retention, diarrhea, vomiting, and overexcitement. 

Benadryl may also adversely react with your cat’s other medications, if she’s taking any for a pre-existing condition. Your vet will most likely opt for a different kind of allergy medication if kitty is taking any of the following:

  • Amitraz for prevention of ticks
  • Central Nervous System (CNS) depressants
  • Epinephrine, which is given for anaphylaxis - an extreme allergic reaction that severely constricts or completely closes the airway
  • Blood thinners, such as heparin and warfarin
  • Selegiline, which is a prescription drug for age-related cognitive dysfunction
  • The antibacterial Furazolidon

Benadryl for Cats: Final Thoughts

Benadryl is relatively safe for cats, but you should always consult your vet before giving kitty any new medication. Even if you have previously treated her with Benadryl, any changes in her overall health, age, and weight will most likely mean a change in dosage, so seek your vet’s advice to be on the safe side. 

You should also make your vet aware of any health issues your cat may have, as well as any medications that she’s taking, including vitamins and herbal supplements. And talk to your vet about alternative treatment options for allergies and the steps you can take to prevent or reduce the risk of your cat suffering from another allergic reaction.