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.

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.

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.)

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

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

Gastrointestinal:

• Diarrhea
• Vomiting
• Constipation

Cardiovascular:

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