Allergies in Dogs: Types, Symptoms, Testing and Treatment

Signs of Allergies in Dogs

• Itching, scratching, licking and chewing, especially of the paws, face, ears, armpits, belly and groin^2,1
• Red skin, rashes, hair loss and hot spots from scratching¹
• Repeated ear infections and skin infections^2,12
• Rubbing the face and eyes; about 15% of dogs with environmental allergy also develop inflammation inside the nose (rhinitis) and asthma¹

Types of Allergies in Dogs

• Flea allergy: a reaction to flea saliva that causes intense itch on the lower back, tail base and thighs. A few bites are enough, so you may never see fleas.¹³ See fleas on dogs.
• Environmental allergy (atopic dermatitis): an inherited tendency to react to pollens, dust mites and molds. Signs usually start between 6 months and 3 years of age and may be seasonal at first.^2,3 See seasonal allergies in dogs.
• Food allergy: a reaction to a protein in the diet, causing year-round itch and sometimes diarrhea.^4,14 See food allergies in dogs.
• Contact allergy: uncommon; it causes rashes on thinly haired skin that touches the trigger, such as the belly and paws.¹⁵

Which Dogs Get Allergies?

Environmental allergy runs in families. Breeds at higher risk include West Highland White Terriers, Boxers, Shar-Peis, Labradors, Golden Retrievers, Boston Terriers, Shih Tzus and Dalmatians.² English Cocker Spaniels, by contrast, had about one-seventh the odds of an atopic dermatitis diagnosis in a UK study.¹⁶ Figures such as "10% of dogs have allergies" are often quoted, but reliable population data are lacking.¹⁷

How Vets Diagnose Allergies

There's no single test. Vets diagnose environmental allergy by ruling out other causes of itch, step by step:^3,2

1. Check for fleas and mites, and start strict year-round flea control on every pet in the home.^3,13
2. Look for and treat skin and ear infections, which add to the itch.³
3. Run a strict elimination diet for at least 8 weeks to check for food allergy.^8,18
4. If the itch remains, environmental allergy is diagnosed from the dog's history and signs.^3,2

Skin and blood allergy tests come only after that, to choose the allergens for allergy shots. They can't tell you whether a dog has allergies, and blood tests for food allergy aren't reliable.^3,19

Allergy Medicines for Dogs

• Oclacitinib (Apoquel): a daily tablet, FDA-approved in 2013, that reduces itch within a day. It's for dogs 12 months and older. In a long-term study, new urinary infections, vomiting, ear and skin infections each occurred in roughly 9% to 11% of dogs, and it isn't for dogs with serious infections or cancer.^10,20,21
• Lokivetmab (Cytopoint): an injection that blocks an itch signal for about 4 to 8 weeks. It was licensed by the USDA in 2016 and can be used in dogs of any age.^22,23,2
• Ilunocitinib (Zenrelia): a daily tablet approved in 2024. Its label carries a boxed warning that it may reduce response to vaccines, so it's stopped around vaccination as your vet directs, and dogs should be up to date on vaccines before starting it.^24,2
• Steroids such as prednisolone work quickly and are useful for flares, but long-term use carries a high risk of side effects.^8,2
• Cyclosporine works for many dogs but takes 4 to 6 weeks to take effect.²¹
• Antihistamines give only a small, limited benefit; about 25% of owners in one survey rated them very effective.^8,25
• Fatty acids (fish oil) may help a little after 2 months or more but rarely work on their own.^8,26

None of these cure allergies; they control the itch, and most allergic dogs need lifelong management.² Never give human allergy or pain medicines without your vet's advice.

Allergy Shots (Immunotherapy)

Allergen-specific immunotherapy, given as injections or drops under the tongue, is the only treatment that changes how the immune system reacts.² It helps about 60% to 70% of dogs but can take 3 to 12 months to work, so specialists recommend continuing for at least a year before judging it.^9,2,8 Regular rechecks improve the results.⁹

Home Care

• Bathe regularly (often weekly to every 2 weeks) with a gentle or medicated shampoo your vet recommends. Bathing removes allergens from the coat and gives short-term itch relief, and how often you bathe may matter more than which shampoo you use.^8,2
• Keep up flea control on all pets, all year.^3,13
• Wipe paws after walks in pollen season.
• Treat infections early, since they make itch much worse.²⁶

See itchy skin in dogs and yeast infections on dogs' skin.

Frequently Asked Questions

What are the signs of allergies in dogs?

Itching, licking and chewing, especially the paws, face, ears and belly, plus red skin and repeated ear or skin infections.

What is the best allergy medicine for dogs?

It depends on the dog. Apoquel, Zenrelia and Cytopoint work quickly; allergy shots are the only long-term immune treatment. Your vet will match the option to your dog.

Can I give my dog Benadryl for allergies?

Antihistamines help only a minority of dogs. Ask your vet before giving any human medicine.

How do vets test dogs for allergies?

By ruling out fleas, infections and food allergy. Skin or blood tests are used only to choose allergy shots.

Are dog allergy blood tests accurate?

Not for diagnosing allergy. Healthy dogs can test positive, and food allergy blood tests aren't reliable.

Can dog allergies be cured?

No, but they can usually be well controlled. Allergy shots can reduce the need for other medicines.

What's the difference between Apoquel and Cytopoint?

Apoquel is a daily tablet; Cytopoint is an injection that lasts about 4 to 8 weeks. Both reduce itch quickly.

At what age do dogs develop allergies?

Environmental allergies usually start between 6 months and 3 years. Food allergy can start at almost any age.