Dog Itching Won’t Stop? Food vs Pollen — Here’s How to Tell

Quick answer

Is your dog constantly scratching, licking, or chewing? Learn how to distinguish

If your dog is scratching constantly, the easiest way to tell the difference between food and environmental allergies is by looking at the timing of the itch and where it occurs on their body. Environmental allergies, or atopic-dermatitis, are typically seasonal, flare up after outdoor activities, and primarily affect the paws, face, and belly. In contrast, a food-allergy persists year-round, often causes chronic ear infections or digestive upset, and can only be definitively diagnosed through a strict, veterinary-supervised elimination diet trial.

:::key-facts

• Environmental allergies (atopy) are seasonal and triggered by pollen, mold, or dust mites.
• Food allergies are year-round reactions, most commonly to animal proteins like chicken or beef.
• Saliva, hair, and blood tests are highly unreliable for diagnosing food sensitivities.
• A strict 8-to-12-week elimination diet trial is the only reliable way to identify a food allergy.
• Secondary skin infections from scratching must be treated before allergy management can succeed.
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Why it matters

Constant itching, chewing, and licking is more than just a minor annoyance for your dog; it is a significant source of chronic stress and physical discomfort. When a dog scratches relentlessly, they damage their skin's protective barrier. This micro-trauma creates tiny tears in the skin, allowing opportunistic bacteria and yeast to multiply. What started as a simple allergic reaction quickly spirals into a painful secondary skin infection, characterized by hair loss, crusting, and a distinct, musty odor.

Understanding the root cause of the itch is vital because the treatment paths for environmental and food allergies are entirely different. Treating an environmental allergy with dietary changes will not provide relief, while managing a food allergy with lifelong, heavy immunosuppressive medications is unnecessary, expensive, and carries potential long-term side effects. By pinpointing the exact trigger, you can target your therapy, save money on ineffective treatments, and restore your dog's quality of life.

:::ask-boo
How can I tell if my dog's itchy paws are from grass or their food?
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What good looks like

A dog with healthy, well-managed skin is comfortable in their own body. Their skin should be pale pink (or naturally pigmented), smooth, and free of flakes, red patches, or damp, greasy areas. They should be able to sleep through the night without waking up to scratch, and they should not feel the need to constantly lick their paws or rub their face against the furniture.

:::video{src="https://storage.googleapis.com/decennium-global.appspot.com/knowledge_assets/care_guides/dog-itching-won-t-stop-food-vs-pollen-here-s-how-to-tell/inline-1-1780029024427.mp4" poster="https://storage.googleapis.com/decennium-global.appspot.com/knowledge_assets/care_guides/dog-itching-won-t-stop-food-vs-pollen-here-s-how-to-tell/inline-1-still-1780028922470.png" alt="A healthy dog resting peacefully on the floor with clear, non-irritated skin."}
A well-managed dog should have calm, pale skin and be able to rest comfortably without scratching.
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Even if your dog has chronic allergies, "good" looks like controlled symptoms. With a proper management plan, your dog can enjoy outdoor walks, play in the grass, and eat their meals without triggering an intense itch-scratch cycle. The goal is not always a 100% cure, but rather reducing the itch to a level where your dog can live a happy, normal life.

Step-by-step

Distinguishing between food and environmental allergies requires a systematic, patient approach. Follow these steps to identify the culprit behind your dog's itch.

Step 1: Map the itch

Grab a notebook and document your dog's symptoms. Pay close attention to where they scratch and when the itching is worst.

• Environmental Allergies (Atopy): Typically affect the paws (constant licking), face (rubbing muzzle and eyes), armpits, groin, and ankles. Symptoms often spike during spring, summer, or autumn, or after your dog spends time outdoors.
• Food Allergies: Often affect the ears (recurrent ear infections), rear end (scooting and biting the tail base), paws, and belly. The itching is consistent year-round, regardless of the season, and may be accompanied by mild gastrointestinal signs like chronic loose stools, gas, or frequent bowel movements (more than three times a day).

Step 2: Rule out parasites first

Before assuming your dog has an allergy, you must rule out external parasites. Fleas, mites (sarcoptic or demodectic mange), and lice can cause intense itching that mimics allergies. Ensure your dog is on a high-quality, vet-approved flea and tick preventative year-round. Even a single flea bite can cause a hypersensitive dog to scratch excessively for weeks.

Step 3: Conduct a strict elimination diet trial

If the itch is year-round and parasites have been ruled out, your vet will likely recommend an elimination diet trial. This is the only scientifically proven method to diagnose a food-allergy.

• Choose the right food: You cannot use standard over-the-counter "grain-free" or "sensitive skin" diets, as these are often processed on machinery shared with common allergens. Instead, use a veterinary prescription hydrolyzed protein diet (where the proteins are chemically broken down so small that the immune system cannot recognize them) or a novel protein diet (using a single protein source your dog has never eaten before, such as kangaroo, venison, or alligator).
• Enforce absolute strictness: For 8 to 12 weeks, your dog must eat only the prescribed food and water. This means absolutely no standard dog treats, table scraps, flavored medications (including chewable heartworm or flea preventatives—ask your vet for topical or unflavored alternatives), rawhides, or dental chews.

:::pro-tip
To give medication during a food trial, never use peanut butter or cheese. Instead, use a small amount of the canned version of your dog's prescription diet, or bake the dry kibble version into crunchy treats.
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Step 4: Perform the dietary rechallenge

If your dog's itching significantly improves or disappears by the end of the 12-week trial, you must perform a "rechallenge" to confirm the diagnosis. Reintroduce their old food. If the itching, redness, or ear inflammation returns within a few days to two weeks, you have confirmed a food allergy. You can then work with your vet to identify the specific protein trigger (usually chicken, beef, dairy, or wheat) and find a safe, long-term diet.

Wiping your dog's paws after outdoor play removes environmental allergens like pollen before they cause irritation.

Step 5: Implement environmental allergy management

If the elimination diet trial yields no improvement, your dog likely suffers from atopic-dermatitis. While you cannot eliminate outdoor pollens, you can manage the exposure:

• Wipe down after walks: Use a damp cloth or unscented pet wipes to clean your dog's paws, belly, and muzzle after they go outside to remove trapped pollen and dust.
• Bathe regularly: Use a soothing, soap-free oatmeal shampoo or a prescription medicated shampoo containing chlorhexidine and ketoconazole to wash away allergens and control secondary yeast and bacteria.
• Optimize indoor air: Use HEPA air filters in your home and vacuum carpets and upholstery regularly to reduce dust mites and indoor molds.

:::ask-boo
What treats can I give my dog during a hydrolyzed food trial?
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Signs something's wrong

While mild itching is manageable, chronic allergic flare-ups can quickly escalate into severe medical issues. Watch out for these signs that indicate your dog's skin barrier has been compromised:

• Hot spots: Red, moist, raw, and highly painful patches of skin that develop rapidly, often within hours, due to intense chewing and scratching.
• Leathery, dark skin (Lichenification): Skin that has turned thick, black, and elephant-like from chronic rubbing and inflammation.
• Yeast odor: A strong, sweet, or musty smell (often resembling corn chips or stale beer) emanating from your dog's paws, ears, or skin folds.
• Chronic ear discharge: Thick black, brown, or yellow discharge inside the ear canal, accompanied by head shaking and a foul smell.

Chronic scratching can damage the skin barrier, leading to painful secondary yeast or bacterial infections in the ears.

:::warning
If your dog is scratching so intensely that they are breaking the skin, bleeding, crying out, or unable to sleep, they are at high risk for a systemic bacterial infection. Seek veterinary care immediately to get fast-acting relief and prevent severe complications.
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When to call your vet

Allergy management is a lifelong journey that requires a close partnership with your veterinarian. You should schedule an appointment if:

• The itching does not improve after four weeks on a strict elimination diet.
• Your dog develops red, oozing, or scabby skin sores.
• Your dog is constantly shaking their head or scratching at their ears.
• Over-the-counter remedies like oatmeal baths or coconut oil are no longer providing relief.

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Your veterinarian can examine your dog's skin for secondary infections and prescribe targeted anti-itch medications.
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Your vet can prescribe targeted, modern therapies to break the itch cycle. These may include monoclonal antibody injections (such as lokivetmab), daily oral Janus kinase inhibitors (such as oclacitinib), or short-term corticosteroids to reduce acute inflammation. For dogs with severe environmental allergies, your vet may recommend allergen-specific immunotherapy (allergy shots or oral drops) to desensitize their immune system over time.

Common mistakes

• Trusting retail "hypoallergenic" foods: Many commercial pet foods labeled "sensitive skin" or "grain-free" contain trace amounts of chicken or beef due to cross-contamination on manufacturing lines. Only veterinary prescription diets are manufactured under strict purification protocols suitable for a diagnostic trial.
• Cheating on the diet trial: Giving your dog "just one" piece of cheese, a single dropped noodle, or a flavored joint supplement will completely invalidate the elimination diet, forcing you to reset the 8-to-12-week clock.
• Stopping the trial too early: Many owners stop the food trial after 4 or 5 weeks because they don't see immediate results. It takes up to 8 to 12 weeks for the immune system to fully calm down and for old allergens to clear the body.
• Relying on commercial allergy tests: Blood, saliva, and hair tests marketed directly to consumers for food allergies are highly inaccurate. They frequently produce false positives, leading owners to unnecessarily restrict their dog's diet while the true allergen remains unidentified.

:::ask-boo
Are saliva or hair allergy tests for dogs accurate?
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Quick FAQs

Can a dog suddenly develop a food allergy to something they have eaten for years?

Yes. Food allergies develop over time due to repeated exposure. It is incredibly common for a dog to eat chicken or beef for several years without any issues before their immune system suddenly decides to treat that protein as a foreign invader, triggering chronic itching.

Can I use human antihistamines to stop my dog's itching?

While some human antihistamines are safe for dogs under veterinary supervision, they are generally not very effective for canine allergies. Unlike humans, whose allergic reactions are driven heavily by histamines, dogs release a variety of other inflammatory chemicals in their skin. Antihistamines only help about 10% to 15% of itchy dogs, usually acting more as a mild sedative than an itch-reliever.

How long does it take for environmental allergens to leave a dog's system?

Unlike food allergens, which can be completely eliminated from the diet, environmental allergens like pollen and mold are constantly present in the air and soil. Therefore, they never truly "leave" your dog's system. Management of environmental allergies is focused on continuous barrier support (baths, wipes) and medical therapies to prevent the immune system from overreacting.