Quercetin for Dogs: Nature’s Antihistamine

If your dog starts sneezing, scratching, or chewing their paws as the seasons change, you’re not alone. Environmental allergies are increasingly common in dogs, and watching them struggle with the discomfort can be heartbreaking. Thankfully, there’s a natural compound that may help ease their symptoms - Quercetin.

What Are Seasonal Allergies in Dogs?

Environmental allergies in dogs are often seasonal, meaning your dog’s symptoms can surface at different times of the year depending on their triggers.

The onset of symptoms typically begins in spring and can continue throughout summer into autumn, with some relief during the winter months.

Common Symptoms of Environmental Allergies

• Sneezing or reverse sneezing

• Hives

• Runny eyes or nose

• Licking or biting at paws

• Hair loss or thinning coat

• Ear irritation or infections

• Persistent itching and scratching

These types of allergies commonly develop between the ages of 1 to 3 years, but if a dog’s gut becomes compromised, they can occur at any age.

Why Allergies Happen: The Role of Histamines

When an allergy attack occurs, the immune system creates antibodies and releases chemicals into the bloodstream to defend the body. One of the main chemicals released is histamine.

Histamine causes inflammation, redness, and irritation, symptoms many dog owners are all too familiar with.

Once an immune response has been triggered for a specific allergen, the body “remembers” it, creating the same reaction every time the allergen is encountered.

Gut Health and Quercetin: The Hidden Link

Many dog owners may not realize that gut health plays a significant role in the development of seasonal allergies. In fact, a compromised gut barrier can lead to an overactive immune system, making the body more susceptible to allergens.

Quercetin, with its anti-inflammatory properties, helps support the gut’s integrity by reducing intestinal inflammation, which can lower the body’s overall allergic response. Pairing quercetin with gut-supporting supplements like probiotics or prebiotic mucilages can offer additional support, especially if your dog struggles with digestive issues or has a history of allergic reactions.

What Is Quercetin?

This is where quercetin comes in. Quercetin is a flavonoid with powerful antioxidant, antihistamine, and anti-inflammatory properties. It works by stabilizing mast cells, which are the immune cells responsible for releasing histamine. By preventing this release, quercetin helps reduce the allergic response before it begins.

Research has shown that quercetin can inhibit histamine release from mast cells and reduce the production of inflammatory cytokines. Studies have also shown it helps suppress allergic airway inflammation and histamine secretion in sensitized mast cells.

Food Sources of Quercetin

Quercetin is found in many fruits and vegetables and is better absorbed from food than from supplements, but you’d need to feed such large amounts that it becomes unrealistic. Still, these foods can act as a helpful daily top-up:

• Dark berries

• Apple skins

• Blueberries

• Citrus fruits

• Parsley

• Bananas

• Broccoli

• Garlic

• Kale

How to Choose a Quercetin Supplement

When shopping for quercetin, keep these things in mind:

• Choose pure quercetin, not quercetin dihydrate, the latter is water-insoluble and harder to absorb.

• Look for bioavailability enhancers like bromelain, which help the body absorb quercetin more effectively.

• Consider one with added vitamin C as it enhances antioxidant and anti-inflammatory effects by stabilizing mast cells, the cells that release histamine during an allergic reaction, making the two nutrients a dynamic duo.

• Avoid products with fillers, binders, or anti-caking agents, as they may trigger sensitivities, and can reduce the effectiveness of the quercetin.

Recommended Quercetin Supplements for Dogs

Plant & Food Based Quercetin Blends

• Four Leaf Rover – Red Rover

• Four Leaf Rover – Harmony

UK Quercetin Extract Supplements

• Small Breeds (200mg/capsule) - Terranova Quercetin Nettle Complex

• Large Breeds (325.7mg/capsule) - British Supplements – Clean Quercetin

USA Quercetin Extract Supplements

• Small Breeds (200mg/capsule) - Terranova Quercetin Nettle Complex

• Large Breeds (500mg/capsule) - Double Wood Supplements – Quercetin

Feeding Guide for Quercetin

Standard (Maintenance): 5–10 mg per kg of body weight per day

• For general antioxidant support, mild inflammation, and long-term use.

• Can be given once daily or split into two doses.

Moderate (for seasonal allergies or inflammation): 15–20 mg per kg of body weight per day

• For moderate allergy symptoms or inflammatory flare-ups.

• Can be given once daily or split into two doses.

High (Therapeutic): 25 mg per kg of body weight per day

• Short-term use only

• For acute flare-ups, autoimmune conditions, or severe allergy episodes.

• Split into two doses.

If your dog’s feeding guide falls in between multiple capsules, you can give on a rotation to balance the dosage over days, e.g. 1 capsule one day, 2 capsules the next, then back to 1, and so on.

Timing with Other Supplements: Avoiding Conflicts

To maximize quercetin’s effectiveness, it’s essential to space it out from other supplements, especially probiotics, prebiotic mucilages or clay products like bentonite. These supplements can sometimes interfere with quercetin’s absorption. Ideally, quercetin should be given on an empty stomach (either an hour before meals or 3 hours after) to ensure optimal absorption.

Cautions and Safety Notes

• Take seasonal breaks: While quercetin is generally safe for long-term use in dogs with seasonal allergies, it’s best to take a break once their allergy triggers subside. This gives the immune system a chance to self-regulate and helps prevent the body from building a tolerance, keeping the supplement effective when reintroduced the following season.

• Tapering off: A slow taper off quercetin at the end of allergy season is ideal, as it allows you to monitor your dog’s response and ease them off anti-inflammatory support gradually.

• Not suitable for dogs with kidney disease: Avoid giving quercetin to dogs with kidney disease unless discussed with your vet first.

• Avoid in pregnant or lactating dogs: There are no current studies on quercetin’s safety during pregnancy or lactation.

How to Tell If Quercetin Is Working

Unlike medications that may show immediate effects, quercetin’s benefits are more gradual. It can take 2–4 weeks for noticeable improvements in allergy symptoms, such as reduced itching, calmer paws, and fewer flare-ups. The changes may be subtle at first, but over time, you should see a marked improvement in their comfort levels.

How Quercetin Works in Synergy with Other Natural Supplements

Quercetin is a powerful natural antihistamine, but its effects can be enhanced when combined with other compounds that target inflammation, immune balance, and histamine release in complementary ways. Together, these combinations offer stronger, more well-rounded allergy support.

• PEA (Palmitoylethanolamide): Calms the immune response and stabilizes mast cells, just like quercetin.

• Quercetin blocks histamine release.

• PEA reduces itch and inflammation.

• Together, they offer complete support for itchy skin and paw chewing/licking.

• Bromelain: Boosts quercetin’s absorption and adds its own anti-inflammatory support.

• Helps quercetin reach effective levels faster.

• Aids digestion, especially when gut health is compromised.

• Vitamin C: Enhances quercetin’s effects and supports immune balance.

• Amplifies anti-histamine benefits.

• Reduces inflammation and oxidative stress.

• Useful for allergy symptoms linked to gut health.

• Nettle: Offers natural antihistamines and works alongside quercetin.

• Blocks histamine receptors.

• Supports respiratory symptoms like sneezing or watery eyes.

• Colostrum: Helps restore gut health and calm immune reactivity.

• Quercetin reduces allergy symptoms.

• Colostrum supports long-term immune balance.

• Ideal for dogs with gut issues or food sensitivities.

Natural Alternatives to Quercetin

While quercetin can be highly effective for many dogs, it’s not always enough on its own, or some dogs may not tolerate it well.

Below are some natural alternatives that can work in synergy with quercetin:

• Nettle Leaf: Often combined with quercetin, nettle leaf is a natural antihistamine that helps reduce allergic reactions.

• Licorice Root: Known for its ability to soothe inflammation and support the immune system. It’s especially useful for short-term flare-ups.

• Reishi Mushroom: A powerful immune modulator that can help balance immune function, making it a good choice for long-term allergy support.

• PEA (Palmitoylethanolamide): A natural anti-inflammatory compound that can reduce itching, inflammation, and histamine release by calming the immune response and stabilizing mast cells.

• Colostrum: The nutrient-rich first milk produced by mammals after giving birth. It supports the immune system, calms inflammation, and improves gut health, helping reduce allergic responses over time.

Supporting your dog through allergy season doesn’t have to be stressful, with the right natural tools like quercetin, you can help them feel more comfortable, naturally.

© Kayleigh Adams, written for NO BULL Just Natural Health for Dogs.