What You Need To Know About Zyrtec For Dogs?

As a dog parent, you have probably heard of Zyrtec. It is a brand of cetirizine hydrochloride, an over-the-counter (OTC) antihistamine for pets.

Of course, you have definitely heard of Benadryl, which is more familiar to many people since it has existed for ages. So, many of you might wonder, “what is the difference between Benadryl and Zyrtec for dogs?”

In this article, we will find out whether Zyrtec is 100% safe for dogs or not. We will also determine potential side effects and how effective it is as an antihistamine.

Zyrtec For Dogs​


Generally speaking, Zyrtec is safe for dogs. As long as you follow the vet’s prescription, there is no need to worry about your pet.

Part of responsible pet care is making sure that your furball has eaten enough before taking any medications. It is not absolutely necessary but it is always a good practice.

Make sure that every dose you get for your pet only has cetirizine as its active ingredient. Some knock-off products contain harmful ingredients such as pseudoephedrine. To avoid being fooled, only buy from your trusted drug stores. It is better if your vet clinic has its own pharmacy. That way, you can get your prescription without worry.


Obviously, giving the right dosage at the right time makes all the difference. The safety of Zyrtec for dogs would not matter if you fail to meet the prescription requirements. That being said, always consult your vet before giving any medicines or treatments to your pet.

Even if your pet has a previous Zyrtec prescription, there is no guarantee that the same will work for his or her present health condition. So, make it a habit to bring your pet to the vet as soon as he or she starts showing signs of sickness.

However, keep this in mind: normally, Zyrtec is administered orally and once a day. At most, the proper dosage depends on your pet’s weight. For dogs weighing less than 10 lbs., a ½ 10-mg tablet once a day will do. Meanwhile, those weighing 10 lbs. and above can handle a whole 10-mg tablet once a day.

Zyrtec For Dogs

​In some rare cases, following the prescription does not ensure that your pet will not overdose on Zyrtec. Should this happen, bring your pet to the vet immediately. Do not attempt to “google” your way out of this one because it can be fatal. This is especially true if necessary steps are not taken right away.


Mainly, as an antihistamine, Zyrtec for dogs treats allergic reactions and skin problems. The most common one is allergic dermatitis, which is characterized by extreme itchiness. It usually occurs when your pet is one to three years old.

The following symptoms indicate that your pet might be suffering from skin allergies:

  • Excessive chewing of legs and/or paws;
  • Excessive face rubbing and/or scratching due to skin irritation;
  • Excessive head shaking;
  • Excessive licking
  • Hair loss; and
  • Swelling

Side Effects

Of course, no medicine has ever done away with a couple of side effects. As for Zyrtec, here are the common side effects you need to be mindful of over the course of the medication:

  • Constipation
  • Drowsiness
  • Heavy sedation
  • Hypersalivation
  • Urine retention
  • Vomiting

Should you notice your pet showing any of these side effects, stop giving him or her Zyrtec immediately. More importantly, contact the vet and tell him or her as many details as possible. By doing so, you will find out if the dosage needs modification or not. It is also possible that you will get a new antihistamine prescription for your pet.


As we have discussed earlier, Zyrtec for dogs is safe. Nonetheless, you still need to be cautious if your pet experiences the following health conditions:


Some dogs have hypersensitivity. They react adversely to certain antihistamine formulas. If your pet is one of them, do not give him or her Zyrtec without thorough consultation with the vet. If he or she has to undergo a few tests, do not think twice about it.

Zyrtec For Dogs-2

Photo by Mpho Mojapelo on Unsplash

Liver and/or Kidney Failures

Liver and/or kidney failure is a severe health problem not just for us, humans, but for dogs as well. Given this, you must be careful about what you let your pet ingest. It can make the difference between life and death. So, again, always consult the vet to find out if Zyrtec will affect your pet’s existing medical condition(s). After all, it does not hurt to be cautious when it comes to serious matters such as health.


When nursing, dogs pass their milk to their puppies. So, giving your pet medicines during this period is not a smart move. It may affect her newborn puppies.


Pregnant dogs might be highly sensitive to certain medications. Also, there are no substantial research efforts backing the safety of Zyrtec for dogs that are pregnant. So, if your pet is pregnant and needs to take antihistamine, ask the vet for safer alternatives. In some cases, Zyrtec works perfectly fine. However, we cannot easily dismiss the probability that it would not.

Benadryl vs Zyrtec

The main difference between Benadryl and Zyrtec lies in their formulas. The former has diphenhydramine as its active ingredient while the latter has cetirizine. These two work well as antihistamines, depending on your pet’s tolerance and other factors.

Accordingly, Zyrtec causes less sedation than Benadryl. For this reason, some dog parents and vets prefer it over Benadryl.

To Wrap It Up…

Overall, you do not need to worry if your vet prescribes your pet with Zyrtec. As we have proven in our discussion today, Zyrtec for dogs is safe and effective. It is especially true if your pet has allergic dermatitis. Potentially, it is also an ideal treatment for some skin problems characterized by the following symptoms:

  • Excessive itching
  • Excessive biting
  • Hair loss
  • Among others

As a dog parent, of course, you still need to know when it is not absolutely safe for your pet. You need to be cautious about giving Zyrtec to your pet if he or she has any of the following:

  • Hypersensitivity
  • Liver and/or kidney failure

The same goes if your pet is pregnant or nursing. Medications may be extremely harmful to her puppies.

If your pet exhibits any side effects, it could mean two things; it is either:​

  • He or she needs dosage modification
  • He or she needs a different antihistamine formula

Now, only the vet can safely say which is which, so bring your pet to the vet clinic before everything gets worse.

Which antihistamines have you tried for your pets? Which one works best? What other skin treatments do you recommend? Let us know your experiences!

I hope that this discussion has answered all your questions about Zyrtec and antihistamines. Should you have further concerns, do not hesitate to reach out to us! We always love hearing from you!

Thanks for reading. Have a good day ahead!​

Jennifer Wood

Hi there, my name is Jennifer Wood, founder of Eforpets.com - a great resource for pets lovers.

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