Let’s face it, allergies are no fun, and we all have to deal with them to some degree. It may surprise some pet owners to learn that the itchy-eyes, irritated skin, and sneezing that are associated with allergies do not only affect humans but our furry companions as well.

While they often manifest in different ways, allergies can affect our dogs just as much as they can affect us. However, our dogs aren’t exactly able to communicate with us about what’s going on.

So, as a dog owner, what do you do?

What is Zyrtec? 


If you’re prone to seasonal allergies, you've likely heard of the over-the-counter antihistamine, Zyrtec®.

The conventional medication is one of the second-generation antihistamines that is often prescribed for human use in coping with environmental changes that often leave us with stuffy noses and red, itchy eyes.

One of Zyrtec's most appealing features is that it does not cause drowsiness like other antihistamines such as Benadryl.

Although the FDA has not yet approved its use in animals, more and more vets are prescribing the drug for dogs to reduce itching and other clinical signs of allergic reactions.

What is Cetirizine 

Cetirizine is an antihistamine and the active ingredient in Zyrtec and several other allergy medications, including Zyrtec Allergy, Children's Zyrtec Allergy, Children's Zyrtec Hives Relief, PediaCare Children's 24-Hour Allergy, Aller-Tec, and Wal-Zyr.

Cetirizine works by blocking a specific natural substance (histamine) that your body produces when you experience an allergic reaction.

Because it blocks histamine, cetirizine is included among a class of medications referred to as antihistamines.

Zyrtec for Dogs 

If Fido is affected by various allergic reactions, your veterinarian may recommend Zyrtec.

These allergic reactions are typically associated with allergic contact dermatitis and atopic dermatitis.

Both contact dermatitis and atopic dermatitis will trigger allergic reactions such as inflammation, hives, itching, and swelling.

Signs of Allergies in Dogs 

Just like in humans, dogs can also be allergic to nearly anything you can think of. Also similar to humans, certain allergens can have a greater effect on dogs than others.

What Causes Dog Allergies 

Common allergies seen in dogs include those triggered by fleas (particularly the saliva from fleas and flea bites), environmental allergens such as weeds, grass, pollen, and dust mites, as well as food allergies (including the food itself, but more specifically, food additives).

Signs of Allergies in Dogs 

While we may think of allergies in terms of a runny nose and watery eyes, dogs may also show allergy symptoms in those ways as well as others.

If your pup is prone to allergies and/or is having an allergic reaction, you'll likely notice the following symptoms:

  • Skin redness

  • Skin irritation

  • Swelling

  • Excessive itching

  • Rubbing of the face and muzzle repeatedly

  • Biting of the paws or legs

dog scratching itself

If dog allergies are left untreated, hair loss and skin infections, including bacterial infections and yeast infections, as well as hot spots may develop.

Additionally, if your dog has a severe allergic reaction, this can lead to hives and in extreme cases, can cause anaphylactic shock.

Signs of anaphylactic shock can include excessive drooling, the sudden onset of diarrhea, vomiting, seizures, coma, and even death. If you’re able to check your dog’s gums, they may appear paler than normal, instead of a healthy pink. Instead of the normal warmth in their limbs, their legs and paws may also feel cold. Your vet will also be able to detect any abnormalities in your dog’s heart rate and pulse. If you believe that your dog is showing signs of anaphylactic shock, it is imperative that you seek veterinary intervention straight away, as anaphylactic shock can be life-threatening.

Zyrtec Dosage for Dogs 

Generally, a typical dose of Zyrtec for dogs is determined by their size. Your veterinarian will likely prescribe Zyrtec to be given once a day, orally.

However, this is a general rule of thumb and not an exact science. For this reason, it is vital that you see your vet to determine an accurate dosage for your pet.

Furthermore, the dosage of Zyrtec will also vary, based on what you are treating. For instance, the dosage to treat itchy skin will be different from the dose to treat an allergic reaction such as a bee sting.

Zyrtec-D Warnings: What Pet Owners Should Know

Perhaps the most important thing for pet owners to know if choosing to use Zyrtec is to never, ever use Zyrtec-D.

Zyrtec-D contains the active ingredient pseudoephedrine, which can be incredibly harmful to dogs and can cause high blood pressure, seizures, and even death.

Standard Zyrtec and generic Zyrtec contain the active ingredient cetirizine, which veterinarians deem safe when administered appropriately.

Zyrtec Side Effects

Typically, Zyrtec doesn’t present many adverse side effects that are too troublesome for pet owners, especially if you are familiar with the potential side effects of other conventional medications.

However, there is still some concern associated with the use of Zyrtec in dogs. Research shows that antihistamines only work in approximately 30% of dogs (sometimes less!). The worrisome part is that up to 25% of those dogs may experience adverse reactions.

Additionally, antihistamines are not a cure, but more like a ‘band-aid’, which only provides relief. While antihistamines will treat the signs, they will not cure the underlying problem, which may be something more severe than a simple seasonal allergy.

The most common side effect of Zyrtec is sleepiness.

However, other side effects include:

  • Constipation

  • Vomiting

  • Urine retention

  • Impulsive responses

  • Excessive salivation

dog salivating

If your dog gets uneasy or is showing impulsive responses Honest Paws offers the best calming treats for dogs which might help with those issues.

Furthermore, even scarier is the fact that Zyrtec can cause additional issues for dogs with kidney problems and liver problems.

While your dog may no longer show any signs of allergies, it is entirely possible that Zyrtec may exacerbate other issues that may be much worse than itchy skin.

Zyrtec Precautions

As mentioned above, one of the potential side effects of Zyrtec in dogs is urine retention. Urine retention can present serious problems in a dog with kidney problems, as administration of the drug can make the pre-existing conditions much worse.

The same potential harm exists for dogs with liver issues. Zyrtec can lead to further liver conditions and make the current situation worse than before.

Furthermore, there haven’t been enough studies to determine whether or not the drug is safe for pregnant dogs. For that reason, we advise pet owners to steer clear from Zyrtec if your dog is pregnant.

pregnant dog

Additionally, nursing dogs should not be given Zyrtec, as the medication can be passed onto puppies through the mother's milk. Nursing puppies are far too young to be given conventional drugs such as Zyrtec.

Lastly, your vet should always be aware of any other medications being given to your dog. This applies when prescribing a drug like Zyrtec or any other medication.

It’s important for your veterinarian to be informed of everything that your dog is being given so that they can prescribe a drug that is less likely to have adverse effects when mixed with their current medical treatment.

Dog Allergy Home Remedies 

Thankfully, as a pet owner, you have options! There are some extremely effective and safe alternatives to Zyrtec that may support skin health and other ailments.

In fact, the options we are about to list come with virtually no side effects.

Take a look!

Oatmeal Bath

Interestingly enough, oatmeal can serve as a soothing home remedy for irritated, itchy skin.

All you need to do is add water to the oatmeal and apply to irritated skin. Or you can fill a tub and pour the oatmeal into the water.

 Allow your pup to soak in the mixture for up to 10 minutes to relieve irritated skin.

dog on grass

Zyrtec for Dogs: The Bottom Line

At the end of the day, we know you want what’s best for your dog. They are an important, furry member of your family. So when Fido isn’t feeling quite right, it can cause some grief for you, the pet owner.

Zyrtec may be safe for dogs at the appropriate dose. However, it’s better to be safe than sorry. As a pet owner, you should always consult your vet before giving your dog a new medication. You should also learn all that you can about the medication you’re giving to your dog and its potential side effects.

At the end of the day, allergies are no fun. Be informed, consult your vet, and always choose the best option for your pet.

We hope your dog feels better soon!

Frequently Asked Questions (FAQs)

What is Zyrtec?

Zyrtec is an antihistamine that is often prescribed by veterinarians to reduce itching in dogs along with other clinical signs of allergic reactions.

What are signs of allergies in dogs?

Signs of allergies in dogs include skin redness, skin irritation, swelling, excessive itching, rubbing of the face and muzzle repeatedly, and biting of the paws or legs.

What is the Zyrtec dosage for dogs?

Your veterinarian will likely prescribe Zyrtec to be given once a day orally. However, it's vital to speak with your vet to determine an accurate dosage for your pet, as it's generally based on your dog's size.

What are the side effects of Zyrtec?

The most common side effect of Zyrtec is sleepiness. Other side effects can include conspitation, vomiting, urine retention, impulsive responses, and excessive salivation.

What are home remedies for dog allergies?

One of the most common remedies for dog allergies is an oatmeal bath. Oatmeal is a great way to soothe irritated, itchy skin and can be applied as a half-water/half-oatmeal paste or simply added to a warm bath.