Are you wondering whether you can give your dog Benadryl to help with itching, allergies, or anxiety? Benadryl (Diphenhydramine) is generally safe for most dogs when used correctly. However, before administering this medication to your furry friend, it's crucial to know the recommended dosage based on your dog's weight.

Key Takeaways:
  • Benadryl is generally considered safe for most dogs.
  • To calculate Benadryl dosage in milliliters (ml), take your dogs weight in pounds (lbs) and divide it by 2.5.
  • Liquid dosage is ideal for dogs less than 10lbs and tablets are preferred for dogs weighing more than 10lbs.

This article will serve as a comprehensive guide for how much Benadryl you can give your dog, how to calculate the proper dosage, and the potential side effects to keep an eye on. 

Please remember to consult your veterinarian before administering Benadryl or any other medication to your pet. Your vet can assist with dosage amounts based on your dog's needs while providing guidance on monitoring and managing their symptoms.

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Is Benadryl Safe for Dogs?

Benadryl (diphenhydramine) is safe for dogs when given at the appropriate dosage. It is an antihistamine that can help alleviate symptoms of allergies, such as itching, swelling, and sneezing.

The medication comes in various forms, including tablets, capsules, and liquid, and the dosage will vary based on your dog's weight, age, and overall health status.

However, dogs with certain medical conditions may not be good candidates for Benadryl and should only be given the medicine under the guidance of a veterinarian.

Consulting with a veterinarian will help ensure that you use Benadryl safely and effectively to manage your dog's symptoms.

How Much Benadryl is Recommended for Dogs?

When administering Benadryl to dogs, the general recommendation is to give 2 to 4 milligrams per kilogram of body weight, or 0.9 to 1.8 milligrams per pound of your dog's body weight 1-2 times per day. The effects of the medication typically last for around 6-8 hours.

Liquid Benadryl is typically recommended for dogs weighing less than 10 pounds, as this can make it easier to achieve an accurate and appropriate dose.

For dogs weighing more than 10 pounds, most veterinarians recommend tablets, which come in 25-50 mg sizes. Achieving the appropriate dose requires breaking the tablets into quarters as closely as possible. However, it is important to note that the exact dosing will depend on your dog's individual needs and medical history.

Benadryl Dosage Calculator for Pets

Benadryl Dosage Calculator for Pets

Benadryl Dosage Calculator for Pets

Below, enter your pet’s weight to find out the recommended dosage for Benadryl in both milligrams (for capsules) and milliliters (for liquid).

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Your Pet's Benadryl Dosage

In mg (tablets):
In ml (liquid - 12.4 mg/5ml concentration):
Number of 25 mg tablets:

Tablets or Liquid?
Liquid is ideal for cats and dogs weighing less than 10 lbs, and tablets are preferred for pets weighing more than 10 lbs. Make sure to check the ingredients of liquid Benadryl for the artificial sweetener xylitol, as it is toxic for dogs. For those pets who do not like the liquid flavors, the tablets can be more easily hidden in tasty treats.

The typical recommended frequency of Benadryl for pets is up to 3 times per day (every 8 hours in a 24-hour period). Always consult with your veterinarian to find out how often your pet can safely take Benadryl and never give more than the recommended dosage of Benadryl or more often than every eight hours in a 24-hour period. Giving more than the recommended dose of Benadryl or giving too many doses in a 24-hour period increases the risk of Benadryl overdose in your dog or cat.

If you’d like to chat with a veterinarian about a safe dosage and frequency to administer Benadryl to your pet, a virtual vet visit is a great way to connect with a doctor quickly without leaving home.

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Liquid Benadryl Dosage Formula for Dogs

If you need to calculate the appropriate liquid dosage of Benadryl for your dog, you can use a simple formula. First, divide your dog's weight in pounds by 2.5. The result will give you the appropriate dose in milliliters (ml).

For example, if your dog weighs 10 pounds, you would calculate its dosage as follows: 10lbs ÷ 2.5 = 4 ml.

Once you have determined the appropriate dosage, you can measure it using a syringe or a measuring spoon. It is important to note that one teaspoon is equal to 5 ml, so if your dog requires a dose of more than one teaspoon, you will need to use multiple teaspoons to measure the appropriate amount.

Benadryl Dosage by Weight (lbs) Chart

Below is a table illustrating how much Benadryl you can give your dog depending on how much it weighs. 

Dog Weight (lbs) Benadryl dosage (ml)
10 4
20 8
30 12
40 16


60 24
70 28
80 32
90 36
100 40
110 44
120 48
130 52
140 56
150 60
160 64
170 68
180 72
190 76
200 80

What Else Can You Use Benadryl for in Dogs?

In addition to its use in managing allergy symptoms, Benadryl can have a range of other applications when used in dogs. Again, before deciding to treat your dog with Benadryl, you should always consult with your veterinarian.

Some use cases of Benadryl in dogs may include:

It is also worth noting that while Benadryl can be an effective tool in managing specific health issues in dogs, it may not be appropriate for every situation, and other treatments or interventions may be necessary.

Side Effects of Benadryl on Dogs

While Benadryl is generally considered safe for dogs, some potential side effects do exist. Benadryl's most common side effect is drowsiness or sleepiness, which can be a desired effect if the medication intends to help calm an anxious or nervous dog.

However, some dogs may experience other side effects from Benadryl, including:
  • Upset stomach or diarrhea: If your dog experiences diarrhea or an upset stomach, it is essential to discontinue using Benadryl and consult with a veterinarian.
  • Dry mouth or urinary retention: Benadryl can cause these symptoms in some dogs, mainly if taken for an extended period.
  • Increased heart rate or breathing rate: In rare cases, Benadryl can cause an increase in breathing rate or heart rate, which may be a sign of an allergic reaction or overdose.

It is crucial to monitor your dog for any signs of side effects when giving them Benadryl and to consult with a veterinarian if you have any concerns or questions about your pet's health.


In summary, Benadryl (diphenhydramine) can be a helpful and safe medication for treating mild itching, to be used as a mild sedative, and to prevent acute allergic reactions in dogs.

Common side effects of Benadryl in dogs include sleepiness and gastrointestinal symptoms but most dogs will tolerate the medication well.

If you have concerns about giving Benadryl to your dog or if your dog experiences any adverse effects, consult with your veterinarian.

Frequently Asked Questions

How long does Benadryl last in dogs?

Benadryl typically lasts 6-8 hours in dogs. However, the actual duration of effect may vary depending on factors such as your dog's weight, age, and health status.

How long does it take for Benadryl to work on dogs?

Benadryl typically takes effect within 30 minutes to an hour of administration. However, this time may vary depending on your dog's weight, age, and health status.

Can dogs be allergic to Benadryl?

Yes, dogs can be allergic to Benadryl or any other medication. While it is generally well-tolerated, some dogs may experience allergic reactions to Benadryl, such as itching, hives, swelling, or difficulty breathing. 

Can I give my dog Benadryl?

Benadryl is commonly used in dogs with mild-to-moderate allergies. It can help relieve symptoms like itching, sneezing, and watery eyes. However, it's important to talk to your vet before giving your dog Benadryl, as it can interact with other medications or health conditions.

The recommended dosage to administer the medication is typically 0.9 to 1.8 milligrams per pound of your dog's body weight, given 1-2 times per day. Always use the appropriate formulation and dosage for your pet's size and weight, and follow your vet's instructions carefully.

Can I give my dog Benadryl for itching?

Yes, you can give your dog Benadryl for itching. Benadryl contains an antihistamine called diphenhydramine, which can help alleviate itching in dogs.

Can I give my dog human Benadryl?

Yes. Benadryl is an over-the-counter medication that is labeled for humans but is generally considered safe for dogs in the appropriate dosage. Always consult with your veterinarian before giving your dog any medication.

Can I give my dog Benadryl every day?

It is generally safe to give your dog Benadryl daily for short periods, as directed by your veterinarian. However, if you plan to give your dog Benadryl for longer than a few days, you should consult your vet to discuss potential risks or concerns.

Can I use Benadryl to sedate my dog for travel?

While Benadryl may have a mild sedative effect on some dogs, veterinarians typically do not recommend it as a primary sedation method for travel. Instead, discussing options for safe and effective sedation with your veterinarian would be best.

How much Benadryl to give a 50 LB dog?

It is generally recommended to provide two 25-milligram tablets, but it's crucial to consult with a veterinarian beforehand to ensure that Benadryl is suitable for your dog's specific requirements and to verify the correct dosage based on your dog's weight and other health considerations.

Read more: 10 Tips for Traveling with Your Pet