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Apoquel side effects in dogs are reported by many dog owners despite the fact that this is a relatively new drug recently launched on the market. 

If your dog is taking Apoquel, you may therefore be wondering what the risks and side effects in dogs taking this medication are, or perhaps, you may have been seeing already some Apoquel side effects in dogs you own and are wondering how common they are. 

While Apoquel has been benefiting many dogs, there are cases where Apoquel side effects in dogs have been taking place and some of them can be quite serious.

Apoquel for dog allergies

Apoquel for Dogs 

Apoquel (generic name, oclacitinib) is a fairly new medication that was launched in 2014 by the manufacturing company Zoetis. 

Apoquel for dogs is typically prescribed to manage the symptoms of canine atopic dermatitis.

 Canine atopic dermatitis is a medical condition that affects dogs suffering from allergic reactions to allergens in their environment such as pollen, grasses and molds.

Unlike people, when dogs suffer from allergies, their reaction is seen mostly in their skin rather than through sneezing fits and runny noses. 

Dogs suffering from canine atopic dermatitis will therefore develop intense skin itching (pruritus) and associated complications such as secondary yeast or bacterial skin infections.

In the past, canine atopic dermatitis was treated with steroids (oral prednisolone and injectable dexamethasone) or cyclosporine (brand name Atopica, produced by Novartis Animal Health). 

Today, the third option is Apoquel, which has been FDA approved and prescribed to treat canine atopic dermatitis now by many veterinarians and veterinary dermatologists.

Mode of Action

Apoquel for dog allergies works by inhibiting janus kinase (JAK “just another kinase”), special enzymes known for triggering the immune system and causing itching and inflammation. 

By inhibiting these enzymes, dogs are provided with relief because their immune system is suppressed.

 Apoquel is therefore classified as an immune system modulator.

Apoquel is particularly effective considering that it starts working fairly quickly. 

When Zoetis conducted several studies, it was found that Apoquel was capable of effectively inhibiting a cytokine responsible for causing itching, and when it did, it did so much faster compared to steroids. 

A big advantage of using Apoquel is therefore the fact that is provides quick relief from itching (within four hours of administration) without the damaging effects seen with the use of steroids.

However, as most drugs, Apoquel for dogs is not free from side effects. 

When the immune system is suppressed, there can be a cascading chain of events which can lead to secondary problems. 

Following are some side effects of using Apoquel for dogs.

"As much as I am using Apoquel and monitoring my patients carefully, I am still concerned about the long-term use and adverse effects down the road. Today, everyone wants a “quick fix” and Apoquel does work quickly without the damaging effects seen with corticosteroids—and I like that."~Alice M. Jeronim, veterinary dermatologist

Apoquel Side Effects in Dogs

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As mentioned, Apoquel can cause a variety of side effects in dogs. 

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The most common Apoquel side effects in dogs include digestive problems such as vomiting and diarrhea.

 Other side effects include loss of appetite, lethargy, irritation or infection of the skin or ears.

One problem with Apoquel is the fact that it suppresses the immune system. The immune system overreacts to allergies by producing antibodies meant to attack the foreign invader (allergens such as dust, mold or pollen).

While a drug that suppresses the immune system such as Apoquel is good news when it comes to allergic itching, the bad news is that the immune system also plays an important role in protecting a dog's body from bacteria, parasites and even cancer.

According to the manufacturer producing Apoquel, this drug can predispose dogs to infection, inflammatory disease from presence of demodex mites (do not use Apoquel in dogs under 1 year of age for this reason) and it may even exacerbate cancer.

There are also reports from dog owners of dogs developing viral papillomas (warts) after using Apoquel.

 This, again because Apoquel suppresses the immune system.

 Further side effects may include urinary tract infections, reactive, aggressive behavior, drug toxicity to the liver, bone marrow suppression, weight gain and seizures.

How to Report Apoquel Side Effects in Dogs 

Apoquel side effects in dogs can be reported directly to the manufacturing company. 

You can contact Zoetis Inc at 1-888-963-8471. Upon receiving your complaint, the drug company will have to submit a report of adverse drug experience to the FDA.

Adverse reactions can also be filed directly with the FDA using their form. 

Information on how to report an adverse reaction can be found here: Reporting Animal Drugs. 

Preventing Apoquel Side Effects in Dogs

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Apoquel side effects in dogs can be reduced by taking precautionary measures. 

Dogs should have blood work done before starting Apoquel, especially the older dogs since Apoquel should be used with caution in dogs with liver disease or kidney disease.

Because Apoquel can cause toxicity to the liver, it's a good idea to have a complete blood count and chemistry profile done after one month of the dog being on Apoquel, then after 6 months, and then yearly thereafter, suggests Dr. Nicole A Heinrich, a veterinary dermatologist working for McKeever Dermatology Clinics.

While Apoquel is a promising drug that can provide fast relief to a dog's itching and scratching, the risks for Apoquel side effects in dogs is something that needs to be considered. 

If your vet has prescribed your dog Apoquel, most likely he/she has evaluated the benefit and risk ratio based on several factors. 

Taking several precautionary measure can reduce the chances for side effects and dog owners should report any adverse effects immediately to their vet.

"We consider this drug to have a wide safety margin. It appears to be well-tolerated with transient gastrointestinal distress (vomiting, diarrhea, anorexia) possible often upon first administering the drug. If a dog vomits or acts "sick" after a dose, it's best to give with food at subsequent dosings."~Dr. Michael Salkin veterinarian


  • Fleck TJ, Humphrey WH, Galvan BA, et al. Comparison of the onset of anti-pruritic activity of the JAK inhibitor oclacitinib to prednisolone and dexamethasone in an IL-31 canine model of pruritus, in Proceedings. North American Veterinary Dermatology Forum, Louisville, Kentucky, 2013.
  •  Apoquel package insert, Zoetis, February, 2013.
  • DVM360: Apoquel Q&A: Will oclacitinib revolutionize the treatment of allergic dermatitis?
  • Dog Discoveries: Apoquel Side Effects in Dogs

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