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Apoquel Side Effects in Dogs

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Apoquel side effects in dogs can include vomiting, diarrhea, lethargy, and anorexia.  Not all dogs will have these side-effects. The dogs who do have side-effects will likely be limited to gastrointestinal issues.

There’s a general fear in the public that Apoquel side effects in dogs include cancer, although there’s no conclusive evidence on that. Unfortunately, there will always be a small percentage of dogs who fall under the “severe side effect” category. To help lessen the chances of severe side-effects, it’s always a good idea to talk to the veterinarian about any other drugs your dog is on, including supplements.

Apoquel does suppress the immune system, but there’s no proof that it directly causes cancer. By suppressing the immune system, Apoquel quiets down the receptors that tell the body it’s itchy. Getting rid of that intense itching helps the body to rest. Proper rest and nutrition work hand-in-hand to increase immunity, which is exactly what your dog needs.

Indirectly, it’s possible that a compromised immune system could allow for the development of cancer that was already there. 

Every sign and symptom a dog has once placed on Apoquel isn’t necessarily being caused by the drug.

If you suspect your dog is having serious side effects (noted below), speak with the veterinarian. In some cases, a lower dose will reduce Apoquel side effects in dogs.

Severe side effects include increased cholesterol and lipase, low white blood cells and decreased globulins.

Some dogs will develop more lumps and bumps and may develop ear and urinary tract infections. This drug should not be given to dogs under the age of 12 months.

Apoquel was designed to be a short-term solution (two weeks), but has been treated long-term with success.

It is used to treat various types of dermatitis. 

The veterinarian’s job is to address the cause of the itch and provide relief for your dog as soon as possible. Apoquel, which is known to work quickly, is sometimes the best choice.

If the veterinarian thinks your dog would benefit from taking Apoquel beyond 14 days, he/she will assess your dog’s health and reduce the dosage.

Keep reading to get a full understanding of what Apoquel is, how it can help your dog, and how to make an informed decision when discussing Apoquel with the veterinarian.

The Truth about Apoquel Side Effects in Dogs

Apoquel (brand name Oclacitinib) was FDA approved in 2013 for use in dogs with atopic and/or allergic dermatitis.

You worry about your dog and you want to do the right thing.  It’s easy to uncover false reports on adverse effects. It’s also easy to get confused amidst the hype and (sometimes) hysteria. 

For that reason, I went directly to the source:  The United Stated Food and Drug Administration (FDA).

Adverse Drug Effects Reporting 

The FDA currently maintains a database of reported Apoquel side effects in dogs. The information comes from the Center for Veterinary Medicine and is kept updated monthly.

As of October 14th, 2018, there was no report submitted to the database on any side effects (mild to severe) on Apoquel. That included a search using the brand name “Apoquel” and the generic name “Oclacitinib”.

It looks like the latest update was in 2013. In fact, there’s a statement from the FDA that implies a new report is due soon (2017/2018). 


Reports submitted to the database take into account the dosage and diagnosis. In addition, things like product defects are considered.

The most common side-effect noted on the product insert is gastrointestinal upset which may resolve on its own.

Apoquel hasn’t been evaluated for use in combination with steroids or other immune-suppressing drugs.

It’s Still Early Days for Apoquel!

A clear picture of short or long-term effects takes years to develop.  Apoquel has only been on the market for five years.

Naturally, the manufacturers highlight the benefits of a new drug and minimize the potential harm.  

Zoetis, the company behind Apoquel, was recently served a warning on their usage of the word “safe”. 

According to the FDA, the company places a lot of emphasis on the safety of the drug, claiming it is safer than steriods and minimize the risks of Apoquel.

Read the Warning Letter Here

Unusual but Serious Apoquel Side Effects in Dogs

Side effects you probably won’t find on the product insert include:


Dr. Melissa Eisenschenk, DVM, DACVD published an article on the Dog Dermatology Clinic site.

She states, “Interestingly, a few dogs developed polydipsia, increased appetite, and aggression, similar to what may be seen with steroids.”

 Bone Marrow Suppression

Bone marrow is the soft tissue found in the middle of long bones.  If you’re worried about immune system suppression, this is where it starts. 

Red blood cells, white blood cells, and platelets are generated in bone marrow and released into the blood stream. 

These are initially created from stem cells, which then develop into blood cells. The type of blood cells formed are based on what the body requires.

Bone marrow suppression (myelotoxicity) decreases the production of blood cells.  Suddenly, the white blood cells that would normally fight infection are unable to do their job. 

Other drugs that can induce immune suppression include some antibiotics, non-steroidal anti-inflammatory drugs (in rare cases) and drugs used to treat chemotherapy can induce blood marrow suppression.

Don’t Miss Follow-Up Appointments

If your veterinarian prescribes Apoquel for your dog, make sure to stick with the follow-up appointments. He/she will want to monitor your dog to watch for adverse effects.

If any major side effects occur, the veterinarian can take steps to reduce dosage or recommend another course of treatment.

Concerned Veterinarians Take a Closer Look

In 2015, when Apoquel was fresh off the shelf, a round table discussion was held at the North American Veterinary Dermatology Form in Nashville, TN. 

A team of veterinarian professionals came together to discuss reported Apoquel side effects in dogs.

Overall, it was felt that Apoquel was well tolerated.  The concerns they had included weight gain, demodicosis, warts, urinary tract infections, loss of protein in the urine, low white blood cell counts, elevated liver values, and rectal bleeding.

NOTE: Rectal bleeding was seen in 3 patients and doctors were not able to determine that it was caused by Apoquel.

Some patients (dogs) developed malignant tumors.  However, none of the participants felt that Apoquel was to blame.

One dog suffered a heart attack (5 year old Labrador). However, it couldn’t be determined whether Apoquel was the cause.

At the end of the day, participants suspected Apoquel may have contributed to interdigital cysts, pneumonia, and fungal infections.

STATISTIC: Only 1% of pets on Apoquel have shown bone marrow suppression.

Apoquel Versus Cytopoint

The most important factors in considering which drug to administer include the age of the dog, whether the dog is on other medications, and whether the condition can be supported long-term. 

Is Cytopoint Safer than Apoquel?

All drugs have side effects and the range from mild to extreme depends on a number of things including the overall health of the dog and other medications the dog might be taking.

With these two drugs, it’s not a question of which is safer, it’s a question as to which drug will be most effective with fewer side effects. 

Cytopoint is given by injection every month or so.  Apoquel is a tablet that can be administered at home. Either way, your going to have to bring your dog to the vet for follow-up, especially if taking either of these drugs long-term.

Does Dosage Affect Apoquel Side Effects in Dogs?

Any drug administered beyond the recommended dosage could create unwanted side-effects. 

Apoquel side effects in dogs are not well-documented using high doses.

Generally, Apoquel is administered twice per day for 14 days.  If required over a longer period, the dose is alternated every other day.

Dosage depends on the size of the dog. Large breeds between 130 and 175 pounds would be given 16 mg.

Small breeds would only take a half tablet and the dogs that fall in between would take one tablet.

REMEMBER: Your veterinarian will give the appropriate dosage instructions based on the unique breed and health condition of your dog.

Is There an Apoquel Alternative for Dogs?

There are no good alternatives to Apoquel that meet its unique formulation.

Yes, there are other options for atopic dermatitis, but each drug has it’s own unique side effects.

If you are concerned about Apoquel side effects in dogs, make sure to bring it up with your veterinarian.

Is it True That Apoquel Causes Cancer?

I am not a veterinarian, but in the research I’ve done, the answer seems to be “NO”.  Many people will argue that point. 

The reality is that there are no “miracle drugs” on the market.  Side-effects occur in just about every medicine.  In most cases, Apoquel side effects in dogs are mild. The most commonly reported side effects are gastrointestinal upset.

Apoquel, however, is still relatively new and long-term studies have yet to be confirmed.  

Beating Down the Immune System

Suppressing the immune system doesn’t make sense until you understand why it’s done.

The first thing to understand is how allergies work. To be allergic to something means that your body’s defences overreact when exposed to certain things like dust, mold, grass, certain foods, etc. 

In people, one example of a severe allergic reaction would be anaphylaxis.

These are people who are so severely affected by things like bee stings, peanuts, or seafood that they have to carry an Epi-Pen.  That’s because their immune system over-reacts to certain allergens.

Histamines are the Culprit

Histamine is produced by the granules in mast cells and basophils cells (type of white blood cells).

These elements respond to the presence of invading bodies by releasing histamine through the blood stream.

It’s completely normal for the body to do this. In fact, it’s the body’s way of protecting itself against foreign elements.

In people, histamines are released when you have a cold virus, for example. The body signals itself to make more mucus and to protect the thin nasal walls with thick secretions.

It does this to allow other chemicals to step up and clean out the virus or bacteria. 

Unfortunately, in some people – and dogs – the reaction is overkill. Excessive amounts of histamine are released causing symptoms like extreme itch and swelling. 

When this happens to dogs, the skin becomes unbearably itchy. Naturally, the dog scratches the itch.

Over time, the skin barrier breaks open leaving it vulnerable to bacteria. Not only is your dog miserable, but now he has to be treated for a secondary infection

You can treat mild itch with a variety of over-the-counter creams, gels, and lotions. There are a variety of things on the market, including oral supplements, that can help. 

The problem comes when you’re dealing with a systemic problem that goes beyond the typical (mild) allergic reaction.  

What You Need to Know About Suppressing the Immune System.

When talking about Apoquel side effects in dogs, people often refer to the dangers of suppressing the immune system.

What you have to remember is that the immune system of a dog with atopic dermatitis is already over-producing histamine. Histamine is the major element in allergic reactions. It’s the thing that causes the severe itching.

In order to adequately protect the skin barrier, the immune system needs to be tamed.

In the short-term, that’s actually a good thing. In fact, it’s the factor that leads to many veterinarians prescribing Apoquel in the first place.

Apoquel is approved for short-term use and within that 14 day period, you’re probably not going to witness any serious side effects.

Once your dog has been on Apoquel longer, the veterinarian will start watching for signs of bone marrow suppression or serious infection.

Apoquel Just Isn’t Enough

Unless the dog’s condition is treated effectively, Apoquel will just mask the problem.  Yes, it will take care of the itch which will allow the skin to heal.  But what happens when you stop the medication?

If the veterinarian can determine the cause of your dog’s allergies, steps can then be taken to treat those allergies.

It’s easy to get a monthly topical prescription that will eradicate fleas. Ticks? Gone. Allergic to certain foods? Gone.  Some dogs, however, have serious allergies that aren’t that easily taken care of.

Severe itching in dogs isn’t unusual. The problem is when the dog begins to bite and chew the skin.

Inflammation, cracked skin, and infection can settle.  Atopic dermatitis is caused by an allergic reaction to things like dust, mold, grass, certain foods, etc.

The veterinarian may want to try eliminating known allergens while supplementing treatment with corticosteroids. 

Topic creams or shampoos are available to help stop itch.  None of them, however, are as fast-acting as Apoquel.

READ THIS:  7 Flavors of Dermatitis in Dogs 

Companies like Zoetis report their findings based on their own clinical studies. The FDA may request its own set of clinical studies as well 

Clinical studies are conducted through double-blind tests.


doubleblind study is one in which neither the participants nor the experimenters know who is receiving a particular treatment. This procedure is utilized to prevent bias in research results.

The definition above was quoted from the website:

Clinical Trial Examples:

The following is a list of clinical trails related to Apoquel side effects in dogs. Rather than rewrite every study, I’ve included a brief description along with the link.

Example 1

Little PR, King VL, Davis KR, Cosgrove SB, Stegemann MR.

A blinded, randomized clinical trial comparing the efficacy and safety of oclacitinib and ciclosporin for the control of atopic dermatitis in client-owned dogs. Veterinary Dermatology. 2015;26(1):23-e8. doi:10.1111/vde.12186.

This study was first published online Dec 12th, 2014.  Note: Oclacitinib is the generic name for Apoquel.

Click this link to read the study

Example 2

Efficacy of oclacitinib (Apoquel®) compared with prednisolone for the control of pruritus (severe itching) and clinical signs associated with allergic dermatitis in client‐owned dogs in Australia

CONFLICT OF INTEREST:  Please note that the people involved in this study were/are all employees of the manufacturer of Apoquel (Zoetis).

Example 3

A blinded, randomized, placebo-controlled trial of the efficacy and safety of the Janus kinase inhibitor oclacitinib (Apoquel®) in client-owned dogs with atopic dermatitis.

Author Unknown.

Click this link to get to the article text.

Real Stories on Apoquel Side Effects in Dogs

You’re never going to see a drug company release new medication with an insert that reads:  We’re really not 100% sure about this, but it should be okay. 

Prescription medications, especially those that are new to the market, tend to be hyped by the marketplace and feared by consumers.  That’s not always the case, but it is my unbiased observation as a consumer.

I’ve curated a wide variety of anecdotes from various online forums just to give you an idea of how people feel about Apoquel side effects in dogs.  

Anecdotal Quotes Online Forums – Identities Protected

The FDA goes through a rigorous process to determine the safety and effectiveness of any new drug.  The FDA is a science-led organization that calls upon the collective knowledge of its members. 

#Number 1

“My advice is to research the risks and only use it as a last resort. The FDA sent a warning letter to the makers of Apoquel telling them to stop promoting how safe it is.”

Click this link to read the FDA warning letter

“Had our boy on Apoquel and it helped a bit, stopped it while we tried raw feeding which made no difference. Put him back on Apoquel this month and his scratching has stopped, his coat is gleaming and has had nothing but compliments about how good he looks.”

Read:  Raw Meat for Dog Allergies

#Number 2

“So I am writing to give an update since I started my dog Charger on Apoquel. It’s been 2 days and he is not scratching like he was. He is NOT leaving the room to go and rub on things beyond the living room. I read all the responses and was a little scared as some say Apoquel causes cancer.

#Number 3

I am happy to see my dog finally getting some relief. Hydroxyzine was his last allergy med. Did not work. Will follow up with our vet to monitor his progress indeed.”

More Anecdotes:

#Number 4

“My dog has been taking Apoquel for years due to allergy and he’s amazing with it and without the pill he will scratch himself till he bleeds”

#Number 5

“Have a 3 year old staffy mix who’s been on apoquel for almost 2 years for her yeast and allergies. It’s has been amazing for her! I am just now being aware of the horrible story’s. I’m now so scared. But the thing is, my dog is happy and healthy that we know of! My friends dog passed away from being on it for about 2 years as well. “

#Number 6

“My frenchies before and after Apoquel pics so many dogs are happily on this medication with no issues so please don’t be put off by others. You only hear the horror stories but rarely hear the ones that aren’t! My dog is happy and healthy on Apoquel.”

How Drugs Like Apoquel Make it to Market

Clinical tests and trials must be done before the FDA will approve a drug for human

FDA Approval Process

The FDA must make sure that the drug in question has been reviewed by the Center for Drug Evaluation and Research.

In addition, the drug has to be shown to provide benefits that outweigh risks.

A structured framework for drug approval involves:

-Analysis of the target condition and available treatments

-Assessment of benefits and risks from clinical dat

It Boils Down to This

Understanding the risks of any drug is important, just don’t buy into fear from anecdotal evidence.  Yes, serious Apoquel side effects in dogs can happen. However, with careful monitoring by an experienced veterinarian, the risks are minimized.

If you decide to give your dog Apoquel, be consistent with the treatment and do not stop suddenly. Communicate with your veterinarian for the best possible outcome. 

Still worried about immune function and side effects? Talk to your veterinarian about supplementation to keep the immune system as strong as possible. 

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