Allergies in dogs and cats: symptoms, causes and what to do
Help keep your pet comfortable by understanding the signs of allergies in dogs and cats. Learn about common triggers, managing symptoms and treatment options.
Published: 17 September 2026
Key takeaways
- Allergies in dogs and cats are common, especially during the summer months when pollen levels rise.Allergies in dogs and cats are common, especially during the summer months when pollen levels rise.
- Symptoms include persistent scratching, ear infections, watery eyes and skin irritation.Symptoms include persistent scratching, ear infections, watery eyes and skin irritation.
- You should never give pets human allergy tablets - differences in dosage and ingredients make them dangerous for pets.You should never give pets human allergy tablets - differences in dosage and ingredients make them dangerous for pets.
- If symptoms last more than a few days or get worse, speak to your vet.If symptoms last more than a few days or get worse, speak to your vet.
- Pet insurance can help cover the cost of allergy diagnosis and ongoing treatment.Pet insurance can help cover the cost of allergy diagnosis and ongoing treatment.
During the warmer months, we see more pet insurance claims linked to skin irritation, ear infections and other allergy-related conditions. Our latest pet insurance claim data shows that allergies are the fourth most common reason for dogs to need treatment. The average dog allergy claim cost is £372*.
So what should you look out for, and what’s the safest way to help your pet? We’ll cover everything from spotting the symptoms to understanding treatment options.
Common symptoms of pet allergies
Allergy symptoms in pets can be easy to miss at first, especially if they start small. But if your pet is showing any of the signs below, allergies could be to blame:
- Persistent scratching, licking or chewing at the skinPersistent scratching, licking or chewing at the skin
- Redness, rashes or inflamed patchesRedness, rashes or inflamed patches
- Ear infections or frequent head shakingEar infections or frequent head shaking
- Watery eyes or dischargeWatery eyes or discharge
- Sneezing, coughing or wheezingSneezing, coughing or wheezing
- Changes in behaviour, such as restlessness or low energyChanges in behaviour, such as restlessness or low energy
Symptoms of hay fever in dogs look a lot like general itchiness, so it’s worth paying close attention during spring and summer. Cat hay fever can show up in similar ways - watery eyes and sneezing are most common.
If you notice any of these signs, it’s best to keep a note of when they happen and what your pet might have come into contact with. This can be really helpful when you speak to your vet.
For more expert info on caring for different breeds, check out our dog and cat breed guides.
What causes allergies in pets?
Pets can be allergic to a wide range of things. Some of the most common triggers include:
- Pollen and grass - A dog with a grass allergy may come home from a walk and immediately start scratching or biting at their paws. Pollen affects cats too, particularly during hay fever season.Pollen and grass - A dog with a grass allergy may come home from a walk and immediately start scratching or biting at their paws. Pollen affects cats too, particularly during hay fever season.
- Dust and dust mites - These year-round triggers can cause ongoing symptoms, especially in pets that spend most of their time indoors.Dust and dust mites - These year-round triggers can cause ongoing symptoms, especially in pets that spend most of their time indoors.
- Food - Food allergies in dogs can cause skin issues and digestive problems. Common culprits include beef, dairy, wheat and chicken. Cats can also develop food sensitivities over time.Food - Food allergies in dogs can cause skin issues and digestive problems. Common culprits include beef, dairy, wheat and chicken. Cats can also develop food sensitivities over time.
- Fleas - Some pets have a strong allergic reaction to flea bites, known as flea allergy dermatitis. Even a single bite can set off uncomfortable itching.Fleas - Some pets have a strong allergic reaction to flea bites, known as flea allergy dermatitis. Even a single bite can set off uncomfortable itching.
- Other animals - Can dogs be allergic to cats? It’s rare, but yes - some dogs can react to cat dander, and vice versa.Other animals - Can dogs be allergic to cats? It’s rare, but yes - some dogs can react to cat dander, and vice versa.
Our summer months tend to bring a spike in allergy symptoms because pollen levels are higher, pets spend more time outdoors, and exposure to grass and insects increases.
Can you give pets human allergy tablets?
The short answer is no, and it’s important to know why. While it could be tempting to try human antihistamines to help your pet, experts are clear - human allergy tablets are not safe for pets.
Here’s why human allergy medication is risky for dogs and cats:
- Different metabolisms - Pets break down medication differently to humans. Some substances can build up in their system and become toxic.Different metabolisms - Pets break down medication differently to humans. Some substances can build up in their system and become toxic.
- Incorrect dosage - Human doses are far too strong for most animals. Even a small amount could overwhelm a pet’s body and cause serious side effects.Incorrect dosage - Human doses are far too strong for most animals. Even a small amount could overwhelm a pet’s body and cause serious side effects.
- Toxic ingredients - Many allergy tablets, especially ‘non-drowsy’ types, contain decongestants like pseudoephedrine or phenylephrine. These are highly toxic to pets and can cause increased heart rate, high blood pressure, tremors or seizures.Toxic ingredients - Many allergy tablets, especially ‘non-drowsy’ types, contain decongestants like pseudoephedrine or phenylephrine. These are highly toxic to pets and can cause increased heart rate, high blood pressure, tremors or seizures.
- Masking the real problem - Treating symptoms at home might offer short-term relief, but it can hide a more serious underlying condition. This delays proper diagnosis and could allow things to get worse.Masking the real problem - Treating symptoms at home might offer short-term relief, but it can hide a more serious underlying condition. This delays proper diagnosis and could allow things to get worse.
The safest option is always to speak to a vet before giving your pet any kind of medication - including dog antihistamines. Your vet can recommend treatments that are specially designed for animals.
What our specialists say
"During the warmer months, we often see an increase in claims linked to skin irritation, ear infections and other allergy-related issues in pets. Giving pets human medication can do more harm than good. If owners notice any changes in their pet’s behaviour or health, it’s always best to seek advice from a vet rather than trying to treat symptoms at home."
Alex Cross, Chief Customer Officer at Tesco Insurance
When to see a vet
Not every itch needs a vet visit, but there are times when professional advice is essential. You should contact your vet if you notice:
- Symptoms lasting more than a few days without improvingSymptoms lasting more than a few days without improving
- Open sores, swelling or signs of infectionOpen sores, swelling or signs of infection
- Difficulty breathing, persistent coughing or wheezingDifficulty breathing, persistent coughing or wheezing
- Sudden changes in behaviour, such as lethargy or distressSudden changes in behaviour, such as lethargy or distress
- Allergy reactions in dogs that get worse after exposure to pollen, grass or dustAllergy reactions in dogs that get worse after exposure to pollen, grass or dust
Early action can make a real difference. The sooner your vet can identify the cause, the sooner your pet can get the right treatment and feel more comfortable.
Find out how pet insurance could help with unexpected vet bills in our guide - Why is pet insurance important?
Recently been to the vet? Find out how to make a claim if you have Tesco Pet Insurance - Make a Pet Insurance claim.
How vets treat allergies in pets
Treatment for pet allergies depends on the type and severity of the reaction. Your vet might recommend one or a combination of the following:
- Vet-prescribed antihistamines or medications - These are specially formulated for animals and dosed to suit your pet’s size and weight.Vet-prescribed antihistamines or medications - These are specially formulated for animals and dosed to suit your pet’s size and weight.
- Skin tests or blood tests - These help identify the exact allergen causing the problem, which makes targeted treatment possible.Skin tests or blood tests - These help identify the exact allergen causing the problem, which makes targeted treatment possible.
- Special diets - If food allergies are suspected, your vet may suggest an elimination diet to pinpoint the trigger ingredient.Special diets - If food allergies are suspected, your vet may suggest an elimination diet to pinpoint the trigger ingredient.
- Topical treatments - Medicated shampoos, creams and ear drops can soothe irritated skin and help manage flare-ups.Topical treatments - Medicated shampoos, creams and ear drops can soothe irritated skin and help manage flare-ups.
- Ongoing management plans - For chronic allergies, your vet might create a long-term care plan, which could include immunotherapy or regular check-ups.Ongoing management plans - For chronic allergies, your vet might create a long-term care plan, which could include immunotherapy or regular check-ups.
Treatments for dog allergies and cat allergies can vary, so it’s important to follow your vet’s advice rather than relying on general information or home remedies.
How pet insurance can help
Allergy treatment isn’t always a one-off cost. From vet consultations and tests to ongoing medication, the bills can add up - especially for pets with ongoing allergies.
Pet insurance can help take the worry out of these costs. Our pet insurance policies cover vet fees for diagnosing and treating allergies, so you can focus on getting your pet the care they need without any stress about the cost.
Allergy claims are some of the most common types we see, so we know many of our animals are affected. Having the right cover means you’re prepared, whatever the season brings.
Refer a friend - and get a Tesco Gift Card
Refer a friend if you’re a Tesco Pet Insurance customer. And you’ll both get a £30 Tesco Gift Card as part of our pet insurance rewards. T&Cs apply.
Help for Pet Insurance customers
Find out how to manage your policy or make a claim if you have Tesco Pet Insurance.
Important information
Tesco Pet Insurance is arranged, administered and underwritten by Pinnacle Insurance Ltd.
vetfone is provided by Vetsdirect Ltd.
You'll find complete details of the cover, monetary limits, exclusions, excesses and terms in our policy documents.
About our sources
*Tesco Pet Insurance claims payment data, January 2025-February 2026. Provided by Pinnacle Insurance Ltd.
Learn more about Pet Insurance for older dogs
Find cover for the older dog in your life and save money with your Clubcard. Choose Lifetime, Maximum Benefit or Time Limited.