How to Use Liquid Benadryl for Cats: Our Vet Explains

Benadryl is a common over-the-counter medication recommended by veterinarians for things like bee stings, bug bites, and itchiness from allergies. In most healthy kitties, it is safe to use, but be sure that you only do so under the supervision of a veterinarian.

What is liquid Benadryl? When is liquid Benadryl used for cats?

Liquid Benadryl is a form of diphenhydramine, an antihistamine commonly used by people for managing allergies and allergic reactions. It is used in cats to treat the same types of reactions. It can help decrease the severity of bee stings or bug bites, and to decrease itchiness associated with a contact or environmental allergen.

bottle of liquid Benadryl with a little container to contain and administer the liquid

Benadryl is generally recognized as safe to use in a variety of companion animals, as long as the correct dosage is administered. Administration of liquid Benadryl, or any medication, should always be done under the guidance of a licensed veterinarian.

It is not recommended to use liquid Benadryl for cats without consulting with a veterinarian first. While Benadryl (also known as diphenhydramine) can be used to treat allergic reactions in cats, the dosage and frequency of administration can vary based on the cat’s weight, health status, and other factors. Using the wrong dose can lead to serious side effects, including sedation, agitation, rapid heart rate, and respiratory depression.

Additionally, some cats may have underlying medical conditions and Benadryl can cause complications with these. A veterinarian can evaluate your cat’s health history to determine if Benadryl is a safe treatment option, and can also provide guidance on proper dosing and administration.

Dosage for liquid Benadryl for cats

If a veterinarian determines that Benadryl (diphenhydramine) is safe and appropriate for your cat, they will calculate the proper dose based on the cat’s weight, age, medical history, and the reason for treatment. In general, the recommended dosage of Benadryl for cats is 1 mg per pound of body weight, given orally every 8-12 hours.

Only plain Benadryl should be given. Do not give Benadryl that has added ingredients such as decongestants, as these can be toxic to cats. Don’t use Benedryl tablets or capsules on cats as these can be difficult to properly divide for the correct dose.

How to administer liquid Benadryl to cats

To administer any liquid medication to a cat, there are a few technique options:

  1. Using a syringe: A syringe can be used to measure the correct amount of medication and to administer it directly into the cat’s mouth. Gently hold the cat’s head and insert the syringe into the side of the mouth, aiming for the back of the mouth. Check it out here.
  2. Mixing medication with food: Some liquid medications can be mixed with a small amount of wet cat food to make them more palatable for cats. Be sure to watch the cat eat to make sure they have consumed all of the medication. Many cats do not respond well to this method and may stop eating the food that was offered, even if there is no medication in it in the future.
  3. Rewarding the cat: After administering medication, be sure to offer your cat a treat or some extra attention to reinforce good behavior and make medication time a positive experience.

If your veterinarian has prescribed a Benadryl dose for your cat, be sure to follow their exact instructions. Liquid Benadryl is most often administered using a syringe that has milliliter markings on the side. Pay attention to the difference between full milliliter markings (mL) and the hash-lines in between full milliliter doses (just like lines on a ruler, the lines between inches represent a portion of an inch.) If your veterinarian prescribes 0.5mL or “half a milliliter”, only draw up medication to the appropriate line on the syringe.

How liquid Benadryl differs from other forms of Benadryl

Compared to other forms of Benadryl, such as tablets or capsules, liquid Benadryl has a few differences:

  1. Dosage: Liquid Benadryl has a lower concentration, and the total dose depends on the volume of liquid measured out, which allows for more precise dosing compared to tablets or capsules
  2. Absorption rate: Liquid Benadryl is absorbed more quickly by the body compared to tablets or capsules
  3. Administration: Liquid Benadryl might be easier to administer to some cats as it can be mixed with food or given directly into the mouth with a syringe. Who here’s tried to pill a cat?!? However it is important to note some cats will not eat if medications are mixed with food. Additionally, some cats take a tablet/capsule hidden in food better than a liquid.

While liquid Benadryl may have certain advantages, the medication should only be given under the guidance of a licensed veterinarian.

Use caution when choosing a Benadryl or a diphenhydramine product for your cat if prescribed by your veterinarian. Some liquid medications contain artificial sweeteners that may not be safe for cats.

Best liquid Benadryl products

Benedryl, or diphenhydramine, is an over-the-counter medication, so you can find it at nearly any pharmacy or retailer. You can even find it online, and it’s not a bad idea to have some on-hand should you need it urgently if your cat gets stung.

Amazon Basic Care Children’s Allergy Liquid is a good option. It is flavored, which your cat doesn’t need, but it doesn’t contain any toxic sweeteners. It is also easy to dose.

Benedryl Children’s Dye-Free Allergy Liquid is another namebrand option that doesn’t contain any sugar or high fructose corn syrup. It also doesn’t contain harmful sweeteners and will be easy to adminster to cats.

Precautions to take when administering liquid Benadryl to cats

  • Consult with a veterinarian: do not give any medication to your cat without consulting your veterinarian first
  • Use plain Benadryl: do not give Benadryl that contains the sweetener xylitol or that has any added ingredients like decongestants or others
  • Measure the correct dose: Only use the measuring device provided in the package or provided by your veterinarian, follow instructions closely
  • Administer the medication safely: Only administer the medication by the route prescribed by your veterinarian (if it is to be given orally, do not administer rectally, or by injection or any other method
  • Watch for side effects: Watch your cat for any signs of side effects or adverse reactions
  • Store the medication properly: Consult the package instructions for storage recommendations

Potential side effects and risks

  1. Sedation: Benadryl can cause drowsiness and sedation in both humans and animals. Benadryl, or a benadryl overdose, can cause your cat to become lethargic or unresponsive.
  2. Dry mouth: Benadryl can cause dry mouth or reduced saliva production
  3. Urinary retention: In some cases, Benadryl can cause urinary retention or difficulty urinating, especially in male cats. This can be a serious condition and requires immediate veterinary attention.
  4. Overdose: Overdose of Benadryl can cause serious health problems in cats, including seizures, coma, and even death. It’s important to follow the dosage instructions provided by the veterinarian and avoid giving additional doses without their guidance.
  5. Interactions with other medications: Benadryl may not be safe to use in combination with certain drugs or medical conditions.

When to visit the vet

Be sure to visit your vet before giving any Benedryl to your cat. This is to ensure that your cat’s issues can be treated with Benedryl and that they are healthy enough to take it. It will also help your vet determine the proper dosage.

Revisit your vet if the Benedryl isn’t helping with your cat’s symptoms. If the itching persists or the swelling from the bee sting doesn’t go down, schedule an appointment. Also, visit your vet if your kitty is experiencing any side effects from the medications. Prolonged sedation, unresponsiveness, seizures, or urine retention require immediate attention.

Frequently Asked Questions

How long does it take for liquid Benadryl to take effect in cats?

In general, liquid Benadryl starts to take effect within 30 minutes to 1 hour after administration. However this can vary depending on several factors, such as age, weight, and medical conditions.

Can I give my cat liquid Benadryl without consulting a veterinarian?

Benadryl should only be used under the guidance of a veterinarian, as the dosage depends on the cat’s weight, medical history, and specific condition. Your veterinarian can help determine whether Benadryl is a safe and appropriate treatment option for your cat’s allergies.

Can liquid Benadryl be used to treat allergies in cats?

Benadryl can be used to treat allergies in cats under the direction of your veterinarian. Benadryl is an antihistamine that blocks the effects of histamine, which is released during an allergic reaction. By blocking the effects of histamine, Benadryl can help alleviate symptoms of allergies, such as itching, sneezing, and inflammation.

What health conditions preclude safe use of Benadryl in cats?

If your cat has a history of any of these conditions, Benadryl may not be safe to use:

  • Glaucoma
  • Cardiovascular disease/ Heart disease
  • Urinary obstruction
  • Hypertension/ high blood pressure
  • Liver or kidney disease
  • Pregnancy or nursing


  • Dr. Bonk, Veterinarian

    Dr. Chyrle Bonk has worked as a licensed veterinarian for Clearwater Valley Veterinary Clinic in Orofino, Idaho for over 10 years. She graduated from Oregon State University in 2010 with a Doctorate in Veterinary Medicine (DVM).

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