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How Much Benadryl Can I Give My Dog? A Guide to Dosage and Alternatives

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It’s fairly common for dogs to have allergies. Some breeds, like Chinese Shar-Peis, Wirehaired Fox Terriers, Golden Retrievers, Dalmatians, Boxers, and Boston Terriers, among others, are predisposed to developing allergies. But any dog breed can get an allergic reaction to something. When they do, it’s essential as a dog parent to know how to treat it naturally or possibly with Benadryl.

Though Benadryl is a human medication made for people, most veterinarians will tell you it’s safe for dogs. After all, dogs can suffer from the same allergens we do. What’s important to keep track of is proper dosage.

This article will detail how to determine Benadryl dosage for dogs, what it’s used for, and the potential side effects. We’ll also review natural alternatives that might help with your dog’s itching, sneezing, runny nose, rash, or other allergy symptoms.

how much benadryl for dog

What Does Benadryl Do?

Benadryl is an over-the-counter antihistamine that also goes by its generic name, diphenhydramine HCL (this is also its active ingredient). Benadryl can help alleviate allergy symptoms in both you and your dog that come from seasonal allergies, environmental allergies, food allergies, and insect bites.

According to Catherine Barnette, DVM, and Ernest Ward, DVM of VCA Hospitals, the most common sign of a dog with an allergy is itching of the skin. Skin conditions can arise in conjunction with respiratory symptoms as well. “In some cases, the symptoms involve the respiratory system, with coughing, sneezing, and/or wheezing.”

Both the brand-name Benadryl and other diphenhydramine medications typically come in tablets of 25 milligrams. Luckily, the math involved to determine the proper Benadryl dose for dogs is quite straightforward.

Benadryl Dose for Dogs

Plumb’s Veterinary Drug Handbook recommends giving a standard dosage of 25 milligrams for a 25-pound dog two to three times per day.

As a general rule of thumb, use 1 milligram per pound of your dog’s body weight. For example, a 50-pound dog would be given two 25 milligram tablets. Small dogs under 25 pounds can be given children’s liquid Benadryl.

According to, at the standard concentration of children’s Benadryl, “every 5 milliliters of liquid contains 12.5 milligrams of diphenhydramine and can be given at a dosage of 0.4 milliliters per pound.”

But before you break open the medicine cabinet or head to the nearest pharmacy for over-the-counter drugs, talk to your vet first to ensure you are giving your pet the right dosage. This is especially critical if your pup is on any other medications or has existing medical conditions.

There are some cases where an allergic reaction is so severe that it requires a trip to the animal hospital for a shot. In such cases, the doctor might need to directly inject the medicine into the dog’s skin so it can act quickly to treat the symptoms.

Be conservative with an antihistamine like Benadryl because an overdose isn’t unheard of. Always consult your vet beforehand as new medications (or overusing the drug) can result in fatal diphenhydramine poisoning.

Signs of Benadryl overdose include constipation, agitation, dilated pupils, seizures, and rapid heart rate. If you suspect your dog is exhibiting signs of Benadryl overdose, contact your vet ASAP or call the Pet Poison Helpline at 855-764-7661.

benadryl dosage for dogs

Side Effects of Benadryl

Will Benadryl make my dog sleepy? It could, yes. Like most over-the-counter medications, Benadryl comes with some potential side effects. Common side effects include drowsiness, dry mouth, hypersalivation, increased heart rate, difficulty breathing, high blood pressure, sedation, urinary retention, and loss of appetite.

To avoid these possible adverse reactions or a potential overdose, consult your veterinarian first to be certain you administer the correct dosage of Benadryl.

Benadryl and Dog Anxiety

We’ve answered the questions, “How much Benadryl can I give my dog?” and “Can I give my dog Benadryl for allergies?” But there are some other instances where diphenhydramine HCL is used for dogs. Here’s what you need to know.

Due to its side effect of drowsiness, some pet parents use Benadryl as a mild sedative for anxious dogs in overwhelming situations like vet visits, car rides, fireworks, or thunderstorms. The Merck Veterinary Manual states that Benadryl may relieve symptoms of mild-to-moderate anxiety in dogs, especially during travel.

If you have a pooch with anxiety, you might also want to consider a natural calming supplement. Calming hemp-based chews, for example, can help make stressful situations less of an anxiety-inducing process. Look for a dog supplement that has soothing active ingredients such as chamomile, ginger root, passion flower, and hemp oil. These ingredients work together to curb your dog’s anxiety by creating a calming effect.

Natural Alternatives to Benadryl

If you’re uncomfortable giving your dog Benadryl for their seasonal allergies, environmental allergies, insect bites, hives, general itchiness, there are a handful of natural alternatives.


There are a number of natural allergy support supplements that support your dog’s health and immune system and give them support with environmental, food, skin and seasonal allergies. These kinds of supplements contain an ingredient called colostrum, an antibody-rich fluid that comes from mammary glands.

DVMs Steve Marsden, Shawn Messonnier, and Cheryl Yuill of VCA Hospitals found that this pre-milk superfood not only helps with  allergies, but it can also help with dental problems like gingivitis, and even food intolerances. Their research also suggests that colostrum is great for a healthy immune system and can help fight bacteria, fungi, and viruses.

In addition to colostrum, many allergy support supplements for dogs contain turmeric for its anti-inflammatory and antioxidant properties. Fish oil also does wonders for dry, itchy skin and it’s a common ingredient in allergy support chews as well.

Ultimately, it can’t hurt to give your pet a high-quality, well-rounded colostrum and turmeric-based allergy support chew as they do more than just help with symptoms of allergies. A supplemental chew that can help with allergies may help keep their immune system in tip-top shape for overall health.

benadryl dosage

The Bottom Line on Benadryl for Dogs

There are plenty of options out there for dogs suffering from allergies. Though Benadryl (or any other brand of diphenhydramine HCL) isn’t the be-all and end-all for relieving allergy symptoms, it can be an effective option for dog health as long as you consult your vet and give your dog the recommended dosage.

To learn more about supporting your pet’s allergies the natural way, check out Pet Honesty’s delicious and health-conscious supplements with all the allergy-fighting ingredients your dog needs to live well.