Benadryl for Dogs: Is It Safe? How Much Can I Give My Dog?

Suffering from pesky seasonal allergies? Having an allergic reaction to an insect bite? Feeling those food allergy or motion sickness woes? Benadryl to the rescue! This over-the-counter antihistamine is a go-to for many of us pet parents. But did you know you can give your dog this human medication, too?

We spoke with a vet expert about the ins and outs of Benadryl for dogs: when it’s appropriate to give a dog Benadryl, how Benadryl can help, how much Benadryl you can safely give your fur baby and more.

Consult your veterinarian before giving your pet Benadryl or any other medication. Your vet can assist with appropriate dosage amounts and provide guidance on managing your dog’s symptoms.

What Does Benadryl Treat in Dogs?

Benadryl has a number of uses for dogs. Dog allergies are definitely a thing, and this over-the-counter med is sometimes the answer. While many uses are related to treating the symptoms of allergies, Benadryl’s benefits go beyond just those.

The following are health conditions your dog could have that you may consider treating with Benadryl (with your vet’s approval):

  • Itchiness from skin allergies/itchy skin
  • Environmental allergies
  • Seasonal allergies
  • Food allergies
  • Swelling/inflammation
  • Hives
  • Runny nose
  • Watery or runny eyes
  • Coughing
  • Sneezing
  • Allergic reactions to insect bites
  • Allergic reactions to insect stings
  • Allergic reactions to snake bites
  • Motion sickness (Benadryl can cause drowsiness)
  • Anxiety (Benadrly has a mild sedative effect)
  • Mast cell tumors (Benadryl helps mitigate histamine-release effects)
  • Used with certain medications or vaccines to prevent allergic reactions

Again, seek your vet’s advice before giving your dog Benadryl. Your vet needs to determine the underlying health condition causing the symptom(s) so they know whether Benadryl is an appropriate treatment.

For example, you may notice your dog has goopy red eyes and think, “It’s allergy season! Fido must have a case of seasonal allergies that are annoying his eyes.”

That’s certainly possible. However, goopy, red eyes are also a symptom of dry eyes or even a health condition that affects the eyes called glaucoma. Benadryl won’t help either of those. Furthermore, the actual problem would remain untreated if you went straight to the antihistamine.

Also note that in the case of anxiety, medication—both prescription and over-the-counter—usually isn’t the first-line treatment. So it’s important that pet parents don’t diagnose and treat their dogs on their own.

What Kind of Benadryl Should I Give My Dog?

And what should I avoid?

Benadryl comes in several forms:

  • Benadryl tablets
  • Benadryl chewable tablets
  • Children’s liquid Benadryl
  • Liqui-gel Benadryl capsules

In addition to the regular form for adults, there’s also children’s Benadryl.

Dr. Jason Dombrosky, DVM, medical director at VEG in San Ramon, California, says one form isn’t necessarily superior to another.

However, he emphasizes, you always want to read the ingredients because some forms, including generics, contain additives that are harmful to dogs. Xylitol, an artificial sweetener, is one example of a dangerous additive. It’s toxic to dogs, so pet parents should always ensure anything they give a dog doesn’t contain it.

Also note that as long as you’re reading ingredients and avoiding additives, a generic form of Benadryl—diphenhydramine is the main active ingredient, and the medication will often be sold under various store brands—is just as effective as the brand name.

The main difference is that the generic form of this over-the-counter med is generally less expensive than the name brand form.

How Much Benadryl Can I Give My Dog?

What’s the correct Benadryl dosage for dogs? And how often can I give my dog Benadryl?

It’s extremely important to ensure you’re giving your dog the correct dosage of Benadryl.

The appropriate dose of Benadryl for dogs is determined by your dog’s weight. The Merck Veterinary Manual states that for every 1 kilogram (or 2.2 pounds) of body weight, you can give your dog 2-4 mgs of diphenhydramine.

An easier way to look at it, especially for small dogs: The correct dosage is roughly 1-2 mg of Benadryl per 1 pound of body weight.

Sticking closer to the lower end of the Benadryl dosage for dogs, the following chart can help you determine the correct dosage of Benadryl for your pup. (It also includes the correct dosage for liquid Benadryl.)

Dog’s weight
Benadryl tablets
Liquid Benadryl
Dog’s weight

10 pounds

Benadryl tablets

10 mg

Liquid Benadryl

4 ml

Dog’s weight

20 pounds

Benadryl tablets

20 mg

Liquid Benadryl

8 ml

Dog’s weight

30 pounds

Benadryl tablets

30 mg

Liquid Benadryl

12 ml

Dog’s weight

40 pounds

Benadryl tablets

40 mg

Liquid Benadryl

16 ml

Dog’s weight

50 pounds

Benadryl tablets

50 mg

Liquid Benadryl

20 ml

Dog’s weight

60 pounds

Benadryl tablets

60 mg

Liquid Benadryl

24 ml

Dog’s weight

70 pounds

Benadryl tablets

70 mg

Liquid Benadryl

28 ml

Dog’s weight

80 pounds

Benadryl tablets

80 mg

Liquid Benadryl

32 ml

Dog’s weight

90 pounds

Benadryl tablets

90 mg

Liquid Benadryl

36 ml

Dog’s weight

100 pounds

Benadryl tablets

100 mg

Liquid Benadryl

40 ml

Benadryl adult tablets typically come in 25 mg tablets. Because of that, it can be a little tricky to get the right Benadryl dosage for dogs using the tablet form of this antihistamine.

While hiding a pill in a treat is usually easier than wrangling your dog to administer a liquid med, you may be able to stick to the dosage guidelines better with liquid Benadryl, especially when it comes to small dogs.

How often can I give my dog Benadryl?

Dr. Dombrosky says you can safely give your dog two to three doses of Benadryl during each 24-hour period as long as you’re following the guidelines for the correct dosage.

What Benadryl Side Effects Should I Watch For?

As with all medications, there are potential side effects when using Benadryl for dogs.

Dr. Dombrosky suggests pet parents keep an eye out for the following:

Common side effects:

  • Drowsiness
  • Dry mouth
  • Urinary retention

Less common side effects:

  • Behavioral changes
  • Gastrointestinal issues
  • Increased heart rate

How to Spot a Benadryl Overdose

Additionally, it’s possible for your dog to experience a Benadryl overdose if the Benadryl dosage guidelines aren’t carefully followed. Dr. Dombrosky says the followings are signs of a Benadryl overdose in dogs:

Central nervous system (CNS):

  • Agitation
  • Excessive excitement
  • Seizures
  • Pronounced sedation


  • Diarrhea
  • Vomiting
  • Constipation


  • Abnormal blood pressure
  • Hypotension (low blood pressure), if xylitol is in the liquid formulation
  • Abnormal heart rate

FAQs about Benadryl for Dogs


Does Benadryl work for an anaphylactic reaction?

A:Benadryl is an antihistamine. However, a dog experiencing anaphylaxis often experiences difficulty breathing, among other serious problems, and it’s an emergency situation that must be assessed and treated by a vet ASAP.


Is Benadryl given to dogs as a premedication for vaccines or medications?

A:Yes, it can be used to cut down the likelihood of a reaction to vaccines as well as medications used for heartworm. Your doctor will advise you on when it’s appropriate to use Benadryl prophylactically (ahead time) to ward off a potential allergic reaction.


Should a pet parent use children’s Benadryl or regular Benadryl?

A:Either is fine, but pet parents must be aware of the concentration, ingredients and correct dosages.


Is Benadryl a mild sedative?



How much Benadryl can I give my dog?

A:Your dog can have 2-4 mg of Benadryl per 2.2 pounds of body weight. Refer to our chart above on Benadryl dosage for dogs.
From an insect bite allergic reaction to motion sickness to seasonal allergies, this over-the-counter antihistamine is pretty versatile. Just remember: While Benadryl is a pretty inexpensive option to treat many health conditions in your dog, pet parents must check with their vet before deciding to give their dog Benadryl. Next, here are more tips on managing dog allergies.

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