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. 

Note: Please remember to consult a veterinarian before administering Benadryl or any other medication to your pet.

Is Benadryl Safe for Dogs?

As a licensed veterinarian, I would say Benadryl 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.

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.

Types of Benadryl

Diphenhydramine comes in various forms, including tablets, capsules, and liquid. Each has its own level of strength in milligrams (mg).

Benadryl is available in:

  1. Tablets - small round tables that come in 25mg or 50mg strength.

  2. Capsules - small capsules that also come in 25mg or 50mg strength.

  3. Liquid - similar to other liquid medications and following a mg/mL dosing, these typically come in a strength of 12.5mg/5ml (2.5mg/ml). If you choose the liquid form, make sure that it does not contain xylitol or other active ingredients.

How Much Benadryl is Recommended for Dogs?

The general guideline for Benadryl dosage is quite straightforward: 1 mg of Benadryl per pound of body weight, administered every 8 to 12 hours. This frequency helps maintain the medication's effectiveness throughout the day.

Benadryl Dosage Chart_01

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 = 4ml.

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.

Dog Benadryl Dosage by Weight Chart

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

Dog Weight (lbs)

Liquid Dosage (mL)*

Tablet Dosage (mg)

Total Daily Dosage (mg)


2 mL

5 mg

10 mg


4 mL

10 mg

20 mg


6 mL

15 mg

30 mg


8 mL

20 mg

40 mg


10 mL

25 mg

50 mg


12 mL

30 mg

60 mg


14 mL

35 mg

70 mg


16 mL

40 mg

80 mg


18 mL

45 mg

90 mg


20 mL

50 mg

100 mg


22 mL

55 mg

110 mg


24 mL

60 mg

120 mg


26 mL

65 mg

130 mg


28 mL

70 mg

140 mg


30 mL

75 mg

150 mg

*Assuming a liquid concentration of 12.5mg/5mL, which is a common formulation. 

Can You Use Benadryl to Treat Allergies in Dogs?

Yes, Benadryl is effective for treating a range of allergy symptoms in dogs. Whether it's seasonal allergies or reactions to an environmental irritant, Benadryl can offer quick relief, making it a go-to in my practice for immediate symptom management.

Here are the allergy symptoms Benadryl can help treat in dogs:

  • Sneezing: Reduces sneezing caused by environmental allergens.

  • Reverse Sneezing: Can alleviate episodes of reverse sneezing, which are often benign but can be triggered by irritants or allergens.

  • Red Eyes: Helps soothe red, irritated eyes resulting from allergic reactions.

  • Watery Eyes: Reduces excessive tear production associated with allergies.

  • Itching: Eases skin itchiness due to allergies, helping to prevent scratching that can lead to skin infections.

  • Hives: Reduces the occurrence of hives secondary to an allergic reaction.

  • Skin Allergies: Offers relief from discomfort caused by allergic dermatitis and other skin allergies.

  • Seasonal Allergies: Mitigates symptoms associated with seasonal allergies, such as pollen.

If you are unsure if Benadryl is the right medication to treat your dog’s allergy-related symptoms, schedule a virtual vet visit with one of our online veterinarians.

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.

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.

Common Side Effects of Benadryl in Dogs

When administering Benadryl, the most frequently observed side effect is drowsiness. This is due to the sedative properties of diphenhydramine, the active ingredient in Benadryl.

While this can be beneficial in calming allergic reactions, it's important to monitor your pet to ensure they are comfortably resting and not overly sedated.

When giving your dog Benadryl, watch for these side effects:

  • Drowsiness: The most common effect, due to Benadryl's sedating properties.

  • Dry Mouth: Increased thirst and frequent water seeking are signs to look out for.

  • Nausea and Vomiting: Less common, but some dogs may become nauseous.

  • Increased Heart Rate: A serious side effect that requires immediate veterinary attention.

  • Rapid Breathing: Another critical sign indicating the medication may not be well-tolerated.

  • Urinary Retention: Difficulty urinating, a less common but important side effect to monitor.

Can a Dog Overdose on Benadryl?

Yes, a dog can indeed overdose on Benadryl. Overdosing can lead to severe health complications. It's crucial to adhere strictly to the recommended dosage guidelines and consult with your veterinarian to prevent such a situation. 

Here are the signs of a Benadryl overdose in dogs that you should be aware of:

  • Rapid Heartbeat: An increase in heart rate beyond the normal range.

  • Dilated Pupils: Noticeable enlargement of the pupils.

  • Agitation or Hyperactivity: Uncharacteristic restlessness or increased activity.

  • Constipation: A noticeable decrease in or absence of bowel movements.

  • Seizures: Convulsions or severe twitching, which are medical emergencies.

  • Dry Mouth: Significantly reduced saliva production or extreme thirst.

  • Urinary Retention: Difficulty urinating or an inability to urinate.

If you observe any of these signs in your dog after administering Benadryl, it's imperative to seek emergency veterinary care immediately.

An overdose requires prompt medical attention to mitigate the risks and ensure your pet's safety and well-being.


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.

Does Your Pet Have Itchy Paws or Flaky Skin?

Our veterinarians can bring relief. Schedule a visit for allergy testing in the comfort of your home.

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

Sources and References

  1. Worth, A.C., Wismer, T.A. and Dorman, D.C., 2016. Diphenhydramine exposure in dogs: 621 cases (2008–2013). Journal of the American Veterinary Medical Association, 249(1), pp.77-82.

  2. Loew, E.R., MacMILLAN, R.O.B.E.R.T. and Kaiser, M.E., 1946. The anti-histamine properties of Benadryl, β-dimethylaminoethyl benzhydryl ether hydrochloride. Journal of Pharmacology and Experimental Therapeutics, 86(3), pp.229-238.

  3. Cortinovis, C., Pizzo, F. and Caloni, F., 2015. Poisoning of dogs and cats by drugs intended for human use. The Veterinary Journal, 203(1), pp.52-58.