Benzocaine for Cats

Benadryl allergy box held up in front of brown and white cat sitting on a tan rug

Cats should occasionally be administered Benadryl, a medicine. While ordinary Benadryl is often safe to provide, it is crucial to understand exactly what Benadryl is, how much to give your cat, when to administer it, and if it is appropriate to administer Benadryl to cats that already have or are at risk for certain medical issues.

What Is Benadryl?

Diphenhydramine hydrochloride is a medication that goes by the brand name Benadryl. Since Benadryl is an over-the-counter antihistamine, a prescription is not necessary to purchase it. Depending on your needs, you may get this antihistamine as pills, capsules, liquid gels, or even liquid in a variety of strengths or milligrams. Sometimes, Benadryl is used alongside additional drugs that cats may find harmful. Because of this, you should be sure to carefully read the packaging when buying the medication to make sure that the medicine you are buying for your cat only contains diphenhydramine, which is the active component in Benadryl. Additionally, your veterinarian may have access to a faster-acting injectable type of diphenhydramine that is available in generic form. Please speak with your veterinarian before contemplating using Benadryl to treat symptoms in your cat.

How Does Benadryl Work?

Benadryl inhibits the effects of histamine on the body since it is an antihistamine. These substances are secreted in the body in response to an allergic reaction in people, dogs, and other animals in addition to cats. The symptoms of allergies or allergic reactions, such as watery eyes, runny noses, swelling, sneezing, itching, and more, are treated with benadryl.

What to Treat With Benadryl

Benadryl is frequently prescribed for cats that have known allergies or who are traveling by vehicle or airline, but there are other situations in which it can be appropriate for your cat. Your veterinarian may prescribe Benadryl in the following situations, for example:

  • When a cat is stung or bit by an .
  • When a cat is bit by a venomous reptile, such as a snake.
  • When a cat is itching or scratching from environmental or food allergies. Flea allergy dermatitis is a common problem in cats and Benadryl may be recommended to temporarily relieve itching while the fleas are treated.
  • When a cat is traveling and may experience motion sickness. Benadryl may help prevent your cat from vomiting as it also has anti-nausea effects.
  • When a cat is in need of something to make it a little sleepy, such as during travel, so that it doesn't get too stressed when it needs to be calm and quiet.
  • When pre-treatment of an antihistamine is needed prior to a vaccination that is known to cause an allergic reaction in that cat. Vaccine reactions are not common but if they do occur or have occurred in your cat in the past, Benadryl may be recommended by your veterinarian.

Even if you never intend to travel with your cat or it doesn't have any known allergies, you should have some Benadryl on hand in your pet first aid kit. Knowing when an insect may strike your cat and trigger an allergic reaction is difficult, if not impossible. Giving your cat a dosage of Benadryl, if you have some on hand, may help to minimize the allergic reaction it might otherwise have. Benadryl or any other over-the-counter drug should not be used without first speaking to your veterinarian.


Some allergic reactions are fatal. Some cats experience an allergic reaction to insects or poisonous reptiles that they become lifeless without prompt medical attention. This is particularly true for breeds like Persians that have brachycephalic or "smush face" faces and already have impaired airways without the additional airway constriction that an allergic response might bring about.

When Not to Use Benadryl

Benadryl is not safe for every cat to take. Some examples of when a cat should not take Benadryl include:

  • If you have a highly stressed or anxious cat and want to make it sleepy. Its anxiety and stress need to be diagnosed and treated by a veterinarian instead of just sedating it with Benadryl.
  • If your , consult your veterinarian before giving Benadryl.
  • If your cat has high blood pressure, consult your veterinarian before giving Benadryl.
  • If your cat has glaucoma, consult your veterinarian before giving Benadryl.
  • If your cat has a chronic medical condition, especially asthma, hyperthyroidism, a seizure disorder, or liver disease, consult your veterinarian before giving Benedryl.
  • If your cat is prone to dry eye (certain breeds are more at risk) or has had injuries to its cornea, consult your veterinarian before giving Benadryl.
  • If your cat is taking specific medications, you should discuss the safety of giving your cat Benadryl with your veterinarian prior to administering it.
  • Benadryl is not the sole remedy, nor is it the most effective treatment available for allergic reactions, motion sickness, or sedation. You should always consult your veterinarian to find the best treatment for the circumstances.

Benadryl Dosage for Cats

Cats typically take two to three doses of 1 mg of Benadryl per pound of body weight each day. According to your veterinarian's advice, a 12.5-pound cat will take 12.5mg (or half of a 25 mg Benadryl pill) up to three times each day. Children's Benadryl liquid may be easier to administer for cats under 12.5 pounds since it can be dosed more precisely, but many cats may object to the bubblegum flavour. It is crucial to constantly confirm that Benadryl contains solely diphenhydramine HCl as its active component.

Potential Side Effects and Risks of Benadryl

Benadryl may make you drowsy, dry mouthed, or have urine retention. It may also disturb your stomach and result in diarrhea and/or vomiting. It can also have a counterintuitive impact on cats, making them hyperactive or too aroused rather than sleeping.

Benadryl Overdose

Giving your cat too much Benadryl may result in either lethargy or enthusiasm. In rare cases, a cat may also have dry mouth, respiratory depression, convulsions, coma, or even death if a sufficient amount is given.

Before giving your cat any type of medication, supplement, or over-the-counter medication, you should always discuss it with your veterinarian.


Before giving your cat any type of medication, supplement, or over-the-counter medication, you should always discuss it with your veterinarian.

If you suspect your pet is sick, call your vet immediately. For health-related questions, always consult your veterinarian, as they have examined your pet, know the pet's health history, and can make the best recommendations for your pet.


"National Center for Biotechnology Information. PubChem Compound Summary for CID 3100, Diphenhydramine. PubChem. Accessed 18 November, 2021", "First Aid for Insect Stings in Cats. VCA Animal Hospital", "Diphenhydramine. VCA Animal Hospital" ;