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It's always best to ask your vet before giving your dog new medications

It should come as no surprise to most dog owners that our furry friends can be affected by allergies just like we can. Itchy skin, watery eyes, sneezing, and a runny nose are all symptoms of canine allergies. So, how can you help?

With Zyrtec.

What is Zyrtec?

Zyrtec is a brand name over-the-counter allergy medication. It contains an antihistamine typically used for human allergy symptoms, such as itchy eyes and stuffy noses. One of the reasons it’s so popular is because it doesn’t cause drowsiness, like Benadryl. While it isn’t FDA approved yet, Zyrtec has become a popular drug for dogs suffering with allergies.

What is Cetirizine?

Cetirizine is the active ingredient in Zyrtec which relieves the allergy symptoms. It works by blocking the natural substances called histamines that your body produces when you experience an allergic reaction. It has become a popular option for dog owners because most dogs handle the medicine well without becoming groggy and sedated.

Zyrtec dosage for dogs

It’s important to talk to your vet for the proper dosing for your furry friend. Generally, one tablet a day is safe for dogs to take, but this can vary based on your dog’s body weight and symptoms. Giving your dog too high of a dosage can actually cause symptoms to worsen or lead to harmful side effects.

🚨 Never give your dog Zyrtec-D. Zyrtec-D contains the active ingredient pseudoephedrine which is extremely dangerous for dogs (it can lead to high blood pressure, seizures, and even death). Zyrtec contains cetirizine, which vets have deemed safe for dogs when used properly.

Potential side effects of Zyrtec

While Zyrtec doesn’t usually show any adverse side effects, every medicine comes with precautions. Research shows that antihistamines only work in about 30% of cases. Also, antihistamines aren’t really a cure, but more of a band-aid to an underlying cause. Zyrtec can also cause additional issues for dogs with kidney problems and liver problems.

The most common side effect of Zyrtec is sleepiness. Others may include:

  • Constipation
  • Vomiting
  • Urine retention
  • Impulsive responses (they might be more irritable or reactive than normal)
  • Excessive salivation

Certain dogs shouldn’t take Zyrtec

Urine retention can present serious problems in a dog with kidney problems. Zyrtec can also lead to further liver conditions and make any current liver or kidney situations worse than before.

There aren’t many studies that look at the use of Zyrtec in pregnant dogs or nursing dogs. One study found that only 3% of the medicine is excreted in the milk, so it is likely safe for nursing pups but it’s best to check in with your veterinarian.

🚨 Your vet should always be aware of any other medications being given to your dog. It’s vital to give your vet all the information, as mixing certain drugs could lead to adverse reactions in your dog.

What do vets think about Zyrtec for dogs?

In a recent trial, 22 dogs with symptoms of canine atopic dermatitis (skin irritation/allergies) were administered a 10 mg tablet Zyrtec daily with a fair response. Four out of the 22 dogs (18%) had “satisfactorily reduced” symptoms, while others showed no benefit or detriment. “Cetirizine was well tolerated by most dogs in this trial, with only 2 dogs (9%) experiencing mild and transient side effects.”

Some vets also recommend other natural ways to help relieve your pup from allergies, such as an omega 3/fatty acid supplement or CBD.

FAQs answered by vets

Q. Do antihistamines only work for seasonal allergies, or do they help with food allergies as well?

A. Antihistamines can help with all allergies because histamines are just a few of the inflammatory mediators that are implicated in allergic reactions. Generally, antihistamines will help with mild allergic reactions.

Q. Can it be given long term or daily, like we humans use it?

A. There aren’t any studies that look at long term use. I know this is a concern in human medicine, but our life expectancy is so much longer, so long term usage seems less likely of a problem for our pups.

The low down on allergies in dogs

Common Causes

There are a few things that can commonly cause allergies in your dog.

  • Fleas. Saliva from fleas and flea bites can trigger allergic reactions.
  • Environmental allergens. Weeds, grass, pollen, and dust mites are all culprits.
  • Food. More than likely, the flavor of the food (lamb, beef, chicken, etc) and sometimes soy, eggs, and dairy can be causes of allergic reaction.


Symptoms or signs that your dog is suffering from allergies include:

  • Skin irritation/hot spots
  • Swelling
  • Excessive itchiness
  • Rubbing of the face and muzzle repeatedly
  • Biting/chewing of the paws or legs

If dogs’ allergies are left untreated, hair loss and skin infections (including bacterial and yeast infections) may develop.

Some allergic reactions may cause anaphylactic shock

In extreme cases, allergic reactions may lead to hives or anaphylactic shock. Signs of this include:

  • Excessive drooling
  • Sudden onset of diarrhea and/or vomiting
  • Pale gums
  • Seizures
  • Coma

👉 If you think your dog may be going into anaphylactic shock, it is imperative to get them to the vet as it is life-threatening and can lead to death.

At the end of the day, allergies are no fun and we just want our fur babies to be happy and healthy. But it’s important to do your research so you can feel confident choosing the best option for you and your pet. And, as always, check with your vet before giving your dog Zyrtec or any other medication.