Cat Benadryl Dosage Calculator

Created by Mariamy Chrdileli
Reviewed by Anna Szczepanek, PhD and Rijk de Wet
Last updated: Sep 28, 2023

Welcome to Omni's cat Benadryl dosage calculator, a simple tool to determine what dose of Benadryl is safe for your cat. If your cat has been displaying symptoms of an allergic reaction, motion sickness, or vomiting 😿 and you've been wondering about Benadryl dosage for cats by weight, our tool is here to help. 👩‍🏫

Some of the critical questions you will get answers to are:

  • What is Benadryl used for?
  • How much Benadryl can I give my cat?
  • Is liquid Benadryl safe for cats?
  • What are the side effects of Benadryl?

❗ Before we talk about Benadryl, keep in mind that you should never give any medication to your pet without consulting your veterinarian.

What is Benadryl and what it is used for?

Benadryl is an antihistamine medication mainly used to relieve symptoms of allergic reactions. When encountering specific allergens (dust, grass, plastic, pollen, fungi, etc.), your cat's immune system may release histamines and other chemicals, which can cause allergic symptoms, such as:

  • Sneezing;
  • Coughing and wheezing;
  • Itchy skin (excessive scratching and overgrooming);
  • Vomiting and diarrhea; and
  • Gas and bloating.

Antihistamines, including Benadryl, decrease the body's response to histamines and alleviate the above-mentioned symptoms. Besides relieving allergic symptoms, your veterinarian may recommend Benadryl for other medical reasons, such as anxiety and the prevention of motion sickness and nausea.

Note that if your cat is experiencing anaphylaxis (a severe allergic reaction that is distinguished by difficulty breathing, facial swelling, seizures, or collapse), Benadryl may not be of help — you need to take your cat to the nearest veterinarian clinic urgently. 🏥

🙋 Benadryl is a brand name for diphenhydramine (antihistamine). Other brand names for diphenhydramine that you may find on the U.S. market are Vetadryl, Banophen, Genahist, Diphenhist, Unisom, and Sominex.

Can cats have Benadryl? Is Benadryl safe for cats?

Although, in general, cats can have Benadryl, you should never give Benadryl to your cat without consulting with your veterinarian to avoid serious health complications. Antihistamine for cats is not always safe, especially considering your cat may be allergic to allergy medication. Here are some precautions you should take to ensure your precious fluffy pet is safely getting the treatment it needs:

  • 💊 Avoid gel capsules, which contain a solvent (a dissolving medium) that can cause irritation or may even be toxic to cats.

  • 💡 Pay attention to the active ingredient of the medication you're purchasing. If the medication contains other active ingredients than diphenhydramine, you need to consult your veterinarian.

  • 🔎 Make sure your cat receives the correct dosage according to its exact weight. If you're in doubt, you can always double-check with your veterinarian and triple-check using our cat Benadryl dosage calculator!

  • 🆘 Monitor your cat's behavior and make sure it is not experiencing any adverse side effects. It would be best if you looked out for

    • Hyperexcitability;
    • Dry mouth;
    • Nausea;
    • Decreased interest in food;
    • Decreased urination;
    • Sedation; and
    • Diarrhea.
  • 👩‍⚕️ Make sure you can reach your veterinarian or nearest veterinarian clinic for help, in case your cat experiences adverse side effects.

How does cat Benadryl dosage calculator work?

Our cat Benadryl dosage calculator is straightforward to use. Here is how it works:

  1. First, you need to enter your cat's weight. Feel free to change units at your convenience.
  2. You'll see the results right away! If it's possible to convert this dosage into quarters of a 25 mg tablet, our cat Benadryl dosage calculator will also do that. You will also be given the amount of liquid and the number of chewable tablets appropriate for your cat.

See the next section if you need to know how to calculate this by hand and what the correct formula is. You can also check out cat calorie calculator to determine the best diet for your cat.

How much Benadryl can I give my cat?

Now that we have established how our calculator works, let's talk about calculating Benadryl dosage for cats by weight. Ensuring that our furry friends receive a safe amount of medication is very important.

Q: How much Benadryl can I give my cat?

A: Veterinarians recommend approximately one milligram of Benadryl per pound of body weight.

Benadryl dosage in mg = cat's weight in lb × 1 mg

Meaning if you have a 10-pound (approximately 4.5 kg) cat, you should give it 10 mg of Benadryl.

Q: Is liquid Benadryl safe for cats?

A: Yes! You can give your cat liquid Benadryl, and sometimes it is easier to measure as well. If you're giving your 10-pound cat Liquid Benadryl with 12.5 mg per 5 ml concentration, you should carefully measure out 4 ml of liquid. Why 4ml? Let's calculate:

First, you need to calculate the number of milligrams you would give your 10-pound cat:

Benadryl dosage in mg = 10 lb × 1 mg

Then you should milligrams into milliliters (remember that liquid concentration is 12.5 mg per 5 ml).

12.5 mg / 5 ml = 2.5 mg/ml

Lastly, you need to divide the weight of our cat by 2.5 ml:

10 / 2.5 = 4 ml

Therefore, 4 ml of liquid Benadryl would be a safe dose for your 10 lb cat!

Still not clear? When in doubt, you can always turn to our cat Benadryl dosage calculator. 😉 For more cat health-related tools, check out our other catty calculators, such as cat chocolate toxicity calculator and cat BMI calculator.

Mariamy Chrdileli
🐈 Your cat's weight
Benadryl dosage
In mg
Liquid (12.4 mg/5ml concentration)
⁍  Number of 25 mg tablets: -
⁍  Number of 12.5 mg chewable tablets: -
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