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Using Zyrtec for Dogs

Allergies can be more than a minor nuisance even for our beloved dogs. The itchy eyes, runny nose, non-stop sneezing, and irritated skin are never fun. Dog allergies are normal and, most of the time, relatively harmless. But as a loving pet parent, you want to spare your fur kid any kind of discomfort. Using Zyrtec for dogs and cats is a commonly prescribed treatment for allergy symptoms. 

As an antihistamine formulated for humans, you should be aware of proper Zyrtec use for your best bud and the precautions you should take. 

Using Zyrtec for Dogs

What is Zyrtec?

Zyrtec is one of the brand names for Cetirizine, an antihistamine that is used to treat itchy skin caused by atopic dermatitis, hives, and insect bites. It also helps relieve other symptoms of an allergic reaction, such as coughing, sneezing, runny or stuffy nose, and irritated eyes. 

As an antihistamine, Zyrtec works by blocking histamine receptors so that the allergic response - the itchiness, etc. - is inhibited. 

Zyrtec is an over-the-counter anti-allergy medication commonly used to remedy the symptoms of seasonal allergies, allergic rhinitis, and even asthma in humans. Unlike Benadryl and other antihistamines, Zyrtec does not cause drowsiness. 

The drug is not approved by the FDA for use in veterinary medicine, but vets commonly prescribe Zyrtec for dogs that suffer from allergies as an equivalent medication for animals is yet to be developed. When a drug is used beyond what is approved by the FDA, it is termed an extra-label or off-label drug.  

Using Zyrtec for Dogs

Zyrtec for Dogs

Veterinarians typically prescribe Zyrtec for dogs who develop allergic reactions associated with atopic dermatitis or allergic contact dermatitis. These reactions include inflammation, itching, hives, and swelling. 

Zyrtec is administered orally, with or without food; if your dog refuses to swallow the medicine or vomits it out, you can crush the tablet into powder or use the oral syrup and mix it with a small amount of food.

Your vet will prescribe the appropriate dosage of Zyrtec tablet or syrup to give to Fido, depending on his weight. The recommended dosage is 1 mg of Zyrtec per kilogram of weight. 

Fido will show signs of improvement within one to two hours after being given the drug. It’s important that you strictly follow when and how much Zyrtec to give your dog. If you miss a dose and he’s supposed to take the medicine once a day, you can give it to him as soon as you remember; if he’s supposed to receive Zyrtec twice a day and you forget to give him the 2nd dose, do not give him an extra dose when the next dose schedule comes around. 

Using Zyrtec for Dogs

What are the potential side effects, risk factors, and contra-indications?

Side effects from Zyrtec are not common, although some dogs may experience increased salivation and vomiting. Small dogs may experience sleepiness if they’re given high doses of Zyrtec. You should stop the medication and consult your vet immediately if you observe severe side effects or if they become worse. 

Zyrtec may not be an option if your dog is or has any of the following:

  • Constipated or has difficulty urinating
  • A history of seizures
  • Glaucoma
  • Thyroid problems
  • Heart, kidney, or liver disease
  • Enlarged prostate
  • Pregnant or nursing 
  • A senior

If Fido is taking any of the following medications, your vet may also advise against using Zyrtec for his allergies.

  • Diazepam and other depressants
  • Digoxin

Additionally, always advise your vet of any supplements or herbal medicines you’re giving Fido as these could also adversely interact with Zyrtec. 

Your vet will normally prescribe standard or generic Zyrtec; but if you’re going straight to the pharmacy or your medicine cabinet, make sure not to give your dog Zyrtec-D which contains pseudoephedrine, an ingredient that can result in high blood pressure, seizures, and even death in dogs. 

Using Zyrtec for Dogs

Causes and Signs of Allergies in Dogs

Dogs can have an allergic response to a wide variety of things, including:

  • Flea bites and saliva
  • Certain foods or food additives
  • Environmental allergens, such as dust mites, grass, pollen, and weeds
  • Insect bites

If you notice Fido exhibiting any of the following symptoms, he may be experiencing an allergic reaction and should be given the appropriate treatment. 

  • Skin irritation, such as itching and redness
  • Runny or stuffy nose
  • Red, irritated, itchy eyes
  • Coughing or sneezing
  • Swelling
  • Repeated rubbing of the muzzle, eyes, and face
  • Frequent biting of paws and legs

Depending on the cause of the allergies, Fido may suffer from hair loss, hot spots, and secondary skin infections caused by bacteria or yeast if his condition is left untreated. As with humans, a severe allergic reaction may also lead to anaphylactic shock, which can be fatal. 

Watch out for signs of anaphylactic shock, which include excessive drooling, pale gums, vomiting, sudden diarrhea, cold and clammy limbs, abnormally fast pulse and heartbeat, seizures, and coma. Take Fido to the vet immediately if any of the aforementioned symptoms appear. 

Using Zyrtec for Dogs

Zyrtec for Dogs: Final Thoughts

Although formulated for humans, Zyrtec is also commonly prescribed by vets to treat mild allergic reactions in dogs, as well as cats and other pets. This is an over-the-counter drug, but it is always best to consult your vet before giving it to Fido to help remedy his allergy symptoms. As with any medication, it’s important to give him the correct dosage and a vet is the only one qualified to determine what it is. If your dog has an underlying condition or is taking other medications, such as vitamins, supplements, herbal medicine, or prescription drugs, mention this to your vet as some meds can adversely interact with Zyrtec.