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dogs and meds

Can I give my dog Benadryl?

What you need to know before giving your dog this antihistamine

Updated March 27, 2020

Created By

Griffin Miller,

It’s common for dog owners to consider giving their pets Benadryl, which is the brand name for the diphenhydramine HCl, the active ingredient. This antihistamine is often taken to relieve the symptoms of allergies in humans, but Benadryl can be effective for dogs much in the same way it is for humans.

That said, it’s generally considered safe to give your dog Benadryl. Although it’s not yet been approved by the FDA for use in animals, it’s fairly common for veterinarians to suggest giving your dog a dose of Benadryl to counteract the symptoms of integumentary diseases (skin-related conditions) and allergic reactions.

What’s the right dosage of Benadryl?

Although there are factors like pre-existing conditions and breed type that may come into play (consult with your vet), the Merck Veterinary Manual suggests the right dosage is 1-2 mg of Benadryl for every pound of body weight. Give your dog the proper dosage twice daily for the best results.

Always start with the low-end dosage. Diphenhydramine is an older generation antihistamine so a side effect is drowsiness. Most of my patients are like zombies when they get the high end of the dose range!

Erica Irish, DVM betterpet Advisor

Give your dog the Benadryl tablets, not liquid caplets. Benadryl comes in 25 mg tablets, which makes it easier to get closer to the exact dosage you need when preparing them for your pet, as opposed to the liquid caps. Plus, they’re easier to break in half for smaller dogs.

Benefits of Benadryl for dogs

The reasons you’d consider giving your dog a dose of Benadryl are similar to the reasons you’d give it to a person:

  • Symptoms of allergies (sneezing, redness of eyes, watery eyes, itching)
  • Reaction to an insect bite or bee sting
  • Skin allergies (redness, itchy skin, inflammation)

Since Benadryl is an antihistamine, it works by blocking the naturally occurring histamines in your dog’s body and some of the symptoms it causes. Keep in mind that when taken by mouth, it takes about 15 to 30 minutes to begin working. If your dog is experiencing some extreme sneezing or itching, it will take a bit of time before they’ll get relief. Don’t rush to give your dog a larger dose until sufficient time has passed for the Benadryl to start working.

In addition to relieving allergy-related symptoms, Benadryl can help with motion sickness and travel anxiety in dogs. Though it should be noted that the drug is not intended for this use and the real reason some believe it’s effective in these cases is that it can make you sleepy.

We’ve all been there — it’s time for a long road trip and your dog won’t stop fussing in the back seat. Maybe it’s their first time flying in a carrier and they’re having trouble getting comfortable or being still. It’s easy to give them a small dose of Benadryl to help them relax, just keep in mind that this is only a quick fix and not a perfect solution.

Since Benadryl just makes dogs sleepy and doesn’t address anxiety, our vets recommend Cerenia (maropitant) for motion sickness. Ask your vet about anxiety treatments before your next road trip. 🚙

Side effects and reasons to not give your dog Benadryl

As with any other drug, there can be side effects. Benadryl can have side effects in humans, not just dogs, so before giving your pup a dose, consider what some of the negative effects can be:

  • Drowsiness
  • Dry mouth

These are signs that Benadryl is probably not the best solution for your dog. Additionally, make sure to check with your vet before giving your dog any Benadryl if they have pre-existing conditions like:

  • Glaucoma
  • Heart failure
  • Prostatic hypertrophy

Benadryl can cause adverse reactions in dogs that have these conditions and those that are similar. One final thing to note is that if your dog is pregnant, it’s unlikely your veterinarian will give you the go-ahead to give them Benadryl at all.

How do I know if my dog is having an allergic reaction to Benadryl?

Similar to side effects, the signs of a severe allergic reaction to Benadryl will look like the following:

  • Rapid heartbeat
  • Dilated pupils
  • Agitation
  • Vomiting
  • Diarrhea

If you suspect your dog is having an allergic reaction to Benadryl, contact your vet or bring them to an emergency veterinarian hospital right away.

Over-the-counter alternatives

If your dog struggles with allergy-related conditions like atopic dermatitis, consider a few of these OTC alternatives that can help make a small dent in your dog’s symptoms.

  1. Quercetin. Quercetin is a flavonol found in many fruits and vegetables that has positive anti-inflammatory qualities. Foods like kale, spinach, blueberries, and strawberries are all rich in quercetin and safe to feed your dog.
  2. Turmeric. The anti-inflammatory qualities of turmeric are well-documented in humans, but they’re just as real with dogs, too. The best part is that it’s more common than ever now to find special pet treats specifically made with turmeric (no need to get messy with turmeric powders).

Baking soda. Funny enough, you can use a basic paste of baking soda and water to treat a red, itchy spot of skin on your dog. Leave the paste on for a few hours before washing clean, and do your best to keep it covered to prevent licking

Common side effects of Benadryl

Benadryl is a relatively safe drug for dogs, though of course there are possible side effects, including drowsiness, dry mouth, rapid breathing, and increased heart rate. Although it’s unlikely your dog will experience adverse effects from Benadryl, it’s important to be aware that they are a possibility. Since there are over-the-counter alternatives, if your dog’s symptoms are relatively mild, you may be better off skipping the Benadryl altogether.

As always, it’s advised to consult with a veterinarian before giving your dog a dose of anything, but if your pet is having a minor case of springtime snuffles, it’s likely more than okay to give them a small amount of Benadryl for relief.