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Nature’s Benadryl: Quercetin

Bailey with Screech

Today we’re going to talk about allergies. You know – itchy skin, red and watery eyes, sneezing, runny nose. Allergies are a pain, and not just for us humans.

When I first got my German Shepherd, she had beautiful fluffy puppy fur, big wet nose, intense red eyes. Wait… what? Red eyes?! Yes, her eyes were red. Not because she was born that way, but because she was allergic to just about everything in her environment. Turns out my poor pup, born on a bed of hay, was allergic to not only grass, but an array of foods and microorganisms floating through the air.

Little did I know a natural solution existed in the peel of many fruits and vegetables: a mighty flavonoid called Quercetin. Although herbs and botanicals have been used for medicinal purposes in many countries for thousands of years, flavonoids were not discovered until the 1930s. Flavonoids are a plant-based compound with powerful antioxidant properties. What do antioxidants have to do with allergies? Well this mighty flavonoid presents not only anti-inflammatory but anti-histamine characteristics too!


An allergy is an abnormal response of the immune system. The body reacts to a usually harmless substance in the environment called an “allergen”. The immune system begins to identify certain everyday substances as dangerous. Allergens can be problematic when inhaled, ingested, or when it comes into contact with a dog’s skin.

As your dog’s body tries to get rid of the allergen, a variety of skin, digestive, and respiratory issues may surface. These include (but aren’t limited to) paw licking/chewing, ear infections, watery eyes, itchy skin, and a lot of scratching.

Remove the Itch!

One of the best ways to address allergies is to remove the allergen. Similarly to us humans, the less exposure to something the body doesn’t like, the less reactive we are to it. The more often your pet is exposed to an allergen they are sensitive to, the more intense and long-lasting their allergic response becomes.

There are two types of allergies: food and environmental. Your dog may have a food allergy which often shows up as itchiness, difficulty breathing, and/or gastrointestinal issues (upset stomach resulting in vomiting, diarrhea, and/or gas). Common food allergens include wheat, soy and corn.

The problem could also be an abundance of yeast. Too often, dogs are diagnosed with allergies when they are actually suffering from a systemic yeast infection which lives in the gut, which is, interestingly, where 70% of the immune system also resides.

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A few common environmental allergens can include: tree, grass and weed pollens, mold spores, dust/dust mites, cleaning products, insect bites, and insect control products. Also, just like us, our pets can have allergic reactions to prescription drugs. To minimize environmental allergens, keep things clean and make sure to use natural and environmentally friendly products and cleaners in and around your home. Limit the amount of time your pet spends outside when pollen counts are high.

The Big Player – Histamine

During an allergy attack, the immune system produces antibodies to a specific allergen. These antibodies then cause certain cells in the body to release chemicals into the bloodstream. One of these chemicals is “histamine”. It’s one of the biggest players in the allergic response, causing much of the inflammation, redness and irritation we and our pets experience. Once the body goes through this process, being exposed to the same allergen again will result in this antibody response, hence the allergic reaction.

A quick safety note: Sometimes, a serious reaction called anaphylaxis can occur. This is essentially a whole body response to an allergen and can be life threatening, therefore requiring immediate medical attention. All the symptoms of a “normal” allergic reaction are exaggerated and your pet may even lose consciousness. Go to the vet immediately!

Nature’s Benadryl

So let’s put what we know together. Quercetin is a flavonoid (also called a bioflavonoid) that has anti-oxidant, anti-histamine and anti-inflammatory properties. During an allergic reaction the body releases histamine. Histamine contributes to inflammation, redness and irritation. Research has shown that Quercetin can “turn off” histamine production and suppress, or at least moderate, inflammation. For this reason, many have coined it “Nature’s Benadryl”.

Furthermore, Quercetin helps suppress cellular activity associated with inflammation. This means less itching! It also inhibits the production of specific inflammatory molecules. This is exciting because Quercetin is actually helpful in treating asthma and respiratory issues involving inflammation. Bronchial tubes in the lungs become restricted during an asthma attack (bronchoconstriction). Medical studies show that Quercetin can actually minimize the amount of constriction!

And There’s More!

Quercetin has an anti-cancer effect!

Flavonoids in fruits and vegetables are important in cancer prevention. According to the University of Maryland Medical Centre, Quercetin and flavonoids have been shown to limit cancer cell growth in breast, colon, prostate, ovarian, endometrial and lung tumors.

Further to this point, our environment is becoming more and more toxic.

Our pets are susceptible to toxins in the environment and in their food. This outpouring of toxins causes inflammation. If the body is overweight and storing fat, this also causes inflammation. And to make matters worse, a lot of those nasty toxins are stored in fat cells. Cancer thrives off low-grade inflammation. Quercetin to the rescue!

Dr Demian Dressler, a renowned vet AKA The Cancer Doctor, adds that there are enzymes that are targeted during low dose chemotherapy treatment (metronomic chemotherapy) with the use of anti-inflammatory drugs. Blood flow to cancer cells is reduced which helps inhibit cancer growth.

Quercetin can partially block the very same enzymes!

Given our pets ingest Quercetin, Dr. Dressler advises using it for tumors in the digestive system where they can receive the highest dosage of a tablet. We will discuss more on supplement dosages shortly. But first, a few more key points about the benefits of Quercetin.

Studies have linked Quercetin to supporting bone health, weight reduction, addressing heart disease and overall performance. Test tube studies have even shown evidence that Quercetin may protect against the damage caused by bad cholesterol (LDL) and reduce blood pressure (hypertension). Really, you and your four-legged friends can’t go wrong with this mighty flavonoid!

Supplement safely

Quercetin can be found in many fruit and vegetables, particularly citrus fruits, apples, grapes, dark cherries, dark berries, onions, and parsley. It also occurs naturally in some teas and red wine. An important note: Onions and grapes may cause TOXIC reactions in pets, therefore do not feed them to your furry friends.

Quercetin supplements are available in pill and capsule form. They are often packaged with “Bromelain” which increases the bioavailability of Quercetin, meaning you get more bang for your buck when combined. Bromelain is an enzyme that also helps inhibit histamine. Together, Bromelain and Quercetin suppress a compound in the body associated with some types of pain and inflammation. Suppressing it can help decrease pain and inflammation that occurs with irritated mucous membranes and body parts.

Using Quercetin

The dosage for Quercetin supplements is often provided for humans weighing approximately 150 pounds and is around 1000mg. Here’s how to convert the dosage for your pet:

  • Take the weight of your pet and multiply it by 1000mg, then divide it by 150 to get the milligram dosage your pet needs.

  • Let’s take my 70-pound Shepherd as an example: (70lb x 1,000mg= 70,000 then divide by 150 = 466 mg).

  • The recommended dosage is 466mg all day. Rounding that to the closest whole number, the dosage for my girl is 500mg per day (best if split in half, meaning one 250mg dosages twice a day).

Research shows that Quercetin supplementation is generally safe for cats and dogs. Some potential side effects that have been observed in humans include upset stomach and headaches. Very high dosages of Quercetin may be damaging to the kidneys. Experts advise against taking it when one has kidney disease. There is not much known about Quercetin during pregnancy and lactation, therefore it is also advisable not to give it to your pet during these times.

Like many supplements, Quercetin isn’t meant to be taken on a long-term basis. Give your pet periodic breaks from the supplement, using only as needed. If your pet does have a preexisting condition, is currently on medication, has a planned surgery, or is pregnant, it’s advisable that you talk to your vet before feeding.

Stop the itch with nature’s Benadryl: Quercetin!

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