The Benefits Of Quercetin For Dogs

Marie Gagne

Fruits and vegetables are great additions to your dog’s diet because of the flavonoids they contain. And there’s one in particular: quercetin.

Quercetin for dogs has some powerful health benefits.  
University of Maryland review showed quercetin can have the following effects …

  • Antioxidant Protection
  • Help Maintain Normal Histamine Levels
  • Help Maintain A Normal Inflammatory Reponse

Here’s a look at the specific ways quercetin can help your dog.

1. Quercetin For Dogs With Seasonal & Environmental Allergies

When your dog has allergies, his body sees the allergen as a threat. Whether it’s pollen, dust, food or something else entirely, his immune system will want it out. To do this, his body releases histamines. Histamines force the allergen from your dog’s system and cause an allergic reaction. You may see reactions like:

  • Sneezing
  • Watery eyes
  • Runny nose

But histamines are also the reason your dog may experience inflammation, redness and irritation. They increase blood flow so his immune system can do its job.  

If you take your dog to the vet, she’ll likely prescribe an allergy drug. But these can do more harm than good and only mask the symptoms.

Quercetin helps maintain normal histamine levels and help can support a normal inflammatory response.

2. Quercetin Supports Respiratory Health

Quercetin is also a good option for asthmatic dogs or dogs with respiratory issues.

During an asthma attack, your dog’s body releases histamines and leukotrienes (2)Like histamines, leukotrienes are a natural immune response. They can cause an increase in mucus production and the narrowing of airways.

Quercetin can help support normal respiratory function and health.

3. Quercetin As Antioxidant

Free radicals are cells with missing electrons. To make themselves whole again, these damaged cells will steal electrons from other cells. But as you can guess … this starts a vicious cycle. One cell is repaired but another is now incomplete.

Free radicals are created when cells metabolize and even during exercise. Toxins in our environment like pesticides and pollution also trigger free radicals.

If the free radicals aren’t controlled, this can cause oxidative stress. Fatty tissue, DNA and proteins are damaged. And this damage can lead to …

  • Premature aging
  • Diabetes

… and many other chronic diseases.

To prevent oxidative stress, your dog must have an adequate supply of antioxidants. Antioxidants have electrons to spare. They stabilize the free radicals and stop the damaging chain reaction. Quercetin can help remove damaging free radicals.

Other Ways Quercetin Helps Dogs

Studies show that chronic oxidative stress is also linked to periodontal disease (6) and bone loss (7)Antioxidants, like quercetin, help to reduce oxidative stress. But that isn’t all they do. Quercetin has been shown to help bone health.   

Quercetin also enhance cardiovascular function (9, 10). It protects against the damage caused by “bad” cholesterol (LDL), reduces blood pressure (hypertension), and protects endothelial function and valuable nitric oxide from oxidative stress. 

Your four-legged friend can’t go wrong with this mighty flavonoid!

Sources of Quercetin for Dogs 

The perfect way to help your dog benefit from these flavonoids is to feed him a balanced raw diet with fruits and vegetables rich in quercetin. Safe choices include:

  • Apples (including the skin)
  • Broccoli
  • Dark leafy greens
  • Peppers
  • Raspberries
  • Blueberries

Caution:  Don’t feed onions and grapes to your dog. They’re full of quercetin, but they can also be toxic to dogs.

If your dog isn’t getting enough fruits and vegetables, you can give your dog a quercetin supplement.

How To Choose A Good Quercetin Supplement for Your Dog

When choosing a supplement, find one that’s sourced from whole foods. Organic powder supplements are the best choice. Find out if they’re produced at temperatures below 118 °F … which means they’re considered raw. 

Tablets, capsules and “chews” are more likely to contain additives that provide little to no benefit to your dog. So always check ingredient lists for things like …

  • Fillers that increase the volume of the supplement … like cornstarch, cellulose or sorbitol. 
  • Binders that hold ingredients together …. like cellulose, sorbitol, gum arabic.
  • Flavorings and sweeteners that make supplements or chews “tasty” for your dog … fructose, sucrose, maltodextrin, artificial flavor (and even “natural flavor” usually isn’t natural). 
  • Colors to make the product more attractive (which your dog doesn’t care about) … avoid artificial colors like Blue 2, Red 3, Yellow 6, etc. 
  • Preservatives like sulfur, selenium, synthetic vitamins (E and C)

There are few rules about what goes into pet supplements. So .. make sure your dog’s supplements only contain the good stuff, and buy one without chemicals, fillers or inactive ingredients. 

Is Quercetin Safe For Dogs?

Research shows quercetin is extremely safe for dogs, even long term. Some side effects seen in people include upset stomach and headaches. So, keep your eye on your dog for any digestive issues or signs he's not feeling his best. 

And if you give quercetin by adding quercetin-rich foods and veggies to your dog's meals, it's "just food" and you don't have to worry about side effects. (Just avoid onions and grapes, as mentioned earlier). 

Caution: If your dog has kidney disease, ask your vet before using quercetin.  Quercetin safety hasn’t been shown for pregnant or lactating females.

That way you can feel confident that your dog's getting all the goodness he can from this incredible flavonoid, quercetin.


  1. Middleton E Jr, Krishnarao DG, Atkins D, Drzewiecki G. The flavonoids: a brief review and study of effects on antigen-induced histamine release from human basophils. Trans Am Clin Climatol Assoc. 1981;92:234-252.
  2. Berger A. What are leukotrienes and how do they work in asthma? BMJ. 1999;319(7202):90.
  3. Mlcek J, Jurikova T, Skrovankova S, Sochor J. Quercetin and Its Anti-Allergic Immune Response. Molecules. 2016;21(5):623. Published 2016 May 12.
  4. Rauf A, Imran M, Khan IA et al. Anticancer potential of quercetin: A comprehensive review. Phytother Res. 2018 Nov;32(11):2109-2130. 
  5. Xu D, Hu MJ, Wang YQ, Cui YL. Antioxidant Activities of Quercetin and Its Complexes for Medicinal Application. Molecules. 2019 Mar 21;24(6):1123.
  6. Wang Y, Andrukhov O, Rausch-Fan X. Oxidative Stress and Antioxidant System in Periodontitis. Front Physiol. 2017 Nov 13;8:910. 
  7. Domazetovic V et al. Oxidative stress in bone remodeling: role of antioxidants. Clin Cases Miner Bone Metab. 2017 May-Aug;14(2):209-216.
  8. Huang YY, Wang ZH, Deng LH, Wang H, Zheng Q. Oral Administration of Quercetin or Its Derivatives Inhibit Bone Loss in Animal Model of Osteoporosis. Oxid Med Cell Longev. 2020 Oct 27;2020:6080597.
  9. Patel RV, Mistry BM et al. Therapeutic potential of quercetin as a cardiovascular agent. Eur J Med Chem. 2018 Jul 15;155:889-904.
  10. Perez-Vizcaino F, Duarte J. Flavonols and cardiovascular disease. Mol Aspects Med. 2010 Dec;31(6):478-94.
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