Apoquel Vs. Zyrtec for Dogs: Comparison Guide

Allergies in dogs can manifest in various ways, from inflamed, itchy skin and relentless scratching to sneezing, watery eyes, and chronic ear infections. It’s a common concern among pet parents, and if your dog is suffering from allergies, you’re likely searching for the most effective, safest treatments to keep them comfortable. 

In this article, we’ll explore two popular allergy medications for dogs: Apoquel vs. Zyrtec. We’ll delve into their differences, benefits, and potential side effects to help you have the right conversation with your veterinarian and ensure your furry family member lives a more comfortable, allergy-controlled life. 

Apoquel Vs. Zyrtec: A Quick Comparison Guide

Apoquel Zyretc
Type of Medication Janus Kinase (JAK) Inhibitor Antihistamine
Active Ingredient(s) Oclacitinib Cetirizine
Used to Treat Itching (pruritus) and inflammation Itching (pruritis), respiratory allergies (sneezing, wheezing, ocular discharge), insect bites, hives (urticaria)
Efficacy Very effective Generally ineffective [1]
Available Forms Oral Tablets, Chewable Tablets Oral Tablets, Chewable Tablets, Liquid Gel Caps, Oral Solution
Prescription or OTC Prescription OTC
Dosing Frequency Twice daily for 1-2 weeks and then once daily for maintenance Once daily
When Does It Start Working? Within 4 hours of administration of the first dose with significant itch relief by 24 hours Within 4-7 hours of administration and peak effects are typically seen after 6-7 days of treatment
Possible Side Effects Transient GI effects (vomiting, diarrhea, anorexia) or lethargy. Increased liver enzymes and seizures have been noted in roughly 1-2 percent of patients. Potential link to increased susceptibility to infections.  Potential link to lowered white blood cell count [2] Vomiting, hypersalivation, drowsiness
Safe for Long-Term Use? Yes, with monitoring Yes
Drug Interactions None CNS depressants (acepromazine, benzodiazepines, opioids), Ivermectin (Heartgard, Tri-heart), P-Glycoprotein Substrates (cyclosporine, digoxin, vincristine)

Differences in How These Dog Allergy Medications Work

Apoquel, also known by its generic name oclacitinib, is a relatively recent addition to the arsenal of allergy relief medications for dogs. It belongs to a class of drugs called Janus kinase (JAK) inhibitors, and its unique mechanism of action sets it apart from traditional allergy treatments.  

This dog allergy medication works by inhibiting the activity of specific enzymes known as Janus kinases. These enzymes are involved in the signaling pathways responsible for inflammation and itching in dogs. By blocking these enzymes, Apoquel helps to alleviate the itching and inflammation associated with allergies directly at the source.

Zyrtec, known by its generic name cetirizine, falls under the category of antihistamines. Antihistamines are a well-established class of drugs used to manage allergies in both humans and dogs.  

Zyrtec works by blocking the effects of histamine, a chemical released by the body during an allergic reaction. Histamine is responsible for many of the classic allergy symptoms in dogs, such as itching, sneezing, and watery eyes. By inhibiting histamine’s actions, Zyrtec can relieve common allergy symptoms. 

Pros and Cons: Apoquel Vs. Zyrtec

Now that we know how these medications provide itch relief for dogs, let’s discuss the major pros and cons of Apoquel vs. Zyrtec.

Pros Cons
Apoquel Apoquel provides quick relief from itching and inflammation, providing your dog with immediate comfort.

This medication specifically targets the enzymes responsible for allergy-related itching, addressing the root cause of the problem.

Numerous studies have demonstrated that Apoquel works very well to quickly and effectively relieve itching and inflammation in dogs.

Apoquel can be used for both short-term and long-term allergy management, providing flexibility for various allergy scenarios.

Due to Apoquel’s highly specific mechanism of action, it will not interact with any other medications your dog may be taking.

Apoquel can be more expensive than some other allergy medications, which can be a deterrent for pet owners on a budget.

While generally well-tolerated, Apoquel can cause side effects like mild gastrointestinal upset or diarrhea in some dogs.  Due to potential links to more serious side effects, veterinarians also recommend annual monitoring, including blood tests to monitor liver enzymes and white blood cell counts.

You can only obtain Apoquel with a veterinarian’s prescription.

Zyrtec Zyrtec is generally more budget-friendly and widely available over-the-counter, which can be cost-effective for long-term use.

Zyrtec is suitable for multiple allergy types. It helps dogs with mild to moderate allergies or for seasonal allergy relief, as well as dogs that experience respiratory allergies, hives, and occasional insect bites.

Zyrtec typically has minimal side effects, with drowsiness being the most common, but not always observed in dogs.

Zyrtec is often available in both pill and liquid forms, making it easier to administer to dogs who are difficult to pill.

Zyrtec has a slower onset and may take time to build up in the dog’s system before providing relief. It’s not ideal for acute symptoms.

Studies have shown that Zyrtec is not as effective at relieving itching and inflammation as Apoquel, so it may not provide relief for severe, uncontrolled allergy symptoms.

Zyrtec addresses symptoms by blocking histamine but does not target the underlying cause of allergies. It may not be as effective for severe or chronic cases.

Some dogs may experience drowsiness as a side effect, which can be undesirable in active dogs or working breeds.

Effectiveness of Apoquel Vs. Zyrtec

When choosing to invest your time and finances in an allergy medicine for dogs, you want to know it’s going to work. Luckily, Apoquel is highly effective in providing rapid, reliable, and targeted relief from dog allergies, itchiness, and skin inflammation. Several studies demonstrated significant improvements in dog itchiness within hours of Apoquel administration  [2] [3].  

In contrast, while Zyrtec, an antihistamine, is effective in managing mild allergies and associated symptoms, research shows that it does not offer the same rapid and reliable relief for severe cases of itchiness and skin inflammation when compared to newer medications such as Apoquel [1]. While it doesn’t hurt to try Zyrtec for a few weeks before calling it a dud, it’s important to manage your expectations when trying this medication to control your pet’s allergies.  

Comparing Side Effects

Another important consideration when selecting Apoquel or Zyrtec for your dog is potential side effects. Generally, both medications are well tolerated in dogs and considered safe for both short and long term use. 

In the short term, Apoquel may lead to mild gastrointestinal upset, including stomach issues or diarrhea. Zyrtec can also cause vomiting, along with hypersalivation and drowsiness as short-term side effects.

When considering longer-term side effects, Apoquel may suppress the immune system, which could potentially make dogs more susceptible to infections. There are also reports of elevated liver enzymes and seizures. Therefore, your veterinarian will recommend annual blood tests for dogs receiving Apoquel long-term. 

In contrast, Zyrtec is considered safe for long-term use, with minimal long-term side effects reported. Annual blood tests and monitoring are generally not necessary for dogs taking Zyrtec chronically. 

It’s important to remember that individual dogs may react differently to medications, so close monitoring and regular veterinary check-ups are crucial for ensuring your dog’s wellbeing while on any medication.

Cost Comparison of Apoquel Vs. Zyrtec

The cost of managing dog allergies with Apoquel is typically more expensive compared to Zyrtec. Apoquel is a prescription medication and the cost is higher due to its specialized mechanism of action and rapid relief. 

While it may seem tempting to go with Zyrtec as the less expensive option, if your dog does not respond to treatment with antihistamines then there is no point spending money on that medication. Additionally, if your dog’s allergies are not managed, you may end up spending additional money treating secondary issues such as chronic skin and ear infections, making it more cost effective to simply pay for Apoquel.  

Can I Give My Dog Apoquel and Zyrtec Together?

Apoquel and Zyrtec can be used together, but this should only be done under the guidance and supervision of a veterinarian. Combining these medications may be necessary when a dog’s allergies are severe or not adequately controlled with one medication alone.

The Bottom Line 

In conclusion, choosing between Apoquel and Zyrtec depends on your dog’s specific allergy condition, the severity of symptoms, the chronicity of their allergies, and your budget.  

Both medications can be effective, but understanding how they work is crucial in determining which one is the best fit for your furry companion’s unique needs. Consulting with your veterinarian is essential to determine the best course of action for your dog’s well-being.


  1. Hsiao, Yun-Hsia et al. “Effects of cetirizine in dogs with chronic atopic dermatitis: a randomized, double blind, placebo-controlled trial.” Journal of veterinary science vol. 17,4 (2016): 549-553. doi:10.4142/jvs.2016.17.4.549 
  1. Marsella, Rosanna et al. “Oclacitinib 10 years later: lessons learned and directions for the future.” Journal of the American Veterinary Medical Association vol. 261,S1 S36-S47. 25 Mar. 2023, doi:10.2460/javma.22.12.0570 
  1. Gadeyne, Caroline et al. “Efficacy of oclacitinib (Apoquel®) compared with prednisolone for the control of pruritus and clinical signs associated with allergic dermatitis in client-owned dogs in Australia.” Veterinary dermatology vol. 25,6 (2014): 512-8, e86. doi:10.1111/vde.12166

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