Spotting the signs of an allergy

Cats are famously stoical, which is why allergies so often creep up on owners unnoticed. Unlike us, cats rarely sneeze their way through hay fever season. Instead, their skin does most of the talking. In the UK, itchy skin is one of the most common reasons cats are taken to the vet, and allergies sit near the top of the list of causes.

Watch out for these clues:

• Constant grooming, especially over the lower back, flanks, belly or inner thighs
• Bald patches or thinning fur, often symmetrical on both sides
• Small scabs or crusts you can feel when stroking your cat — this is known as miliary dermatitis
• Red, waxy or smelly ears that seem to flare up again and again
• Sneezing, runny eyes, or a soft cough that sounds like feline asthma
• Loose stools, vomiting, wind, or a sudden fussiness about food

Any of these lasting more than a week or two deserves a trip to your vet surgery. Cats cannot tell us what feels wrong, so a symptom diary — noting dates, foods, weather and flare-ups — is genuinely one of the most useful things you can bring to an appointment.

Flea allergy: the most common culprit in the UK

Flea allergic dermatitis is the single most frequently diagnosed skin allergy in British cats. The problem is not the flea itself but the protein in flea saliva. A single bite can set off days of intense itching, particularly over the base of the tail and lower back.

Because our centrally heated homes keep fleas active almost all year, treating only in summer no longer works. Use a veterinary-recommended flea product licensed for cats, every month, all year round. Treat every pet in the household at the same time, wash bedding on a hot cycle and vacuum thoroughly, including under furniture and along skirting boards.

Never use a dog flea treatment on a cat. Many contain permethrin, which is highly toxic to cats and can be fatal. If you suspect your cat has been exposed, phone your vet immediately.

Food allergies and sensitivities

True food allergy is less common than most owners expect, but it is real. The usual suspects are chicken, beef, fish, dairy and wheat — often the very proteins cats have eaten happily for years. Signs tend to include itching around the head, neck and ears, sometimes alongside vomiting or diarrhoea.

Diagnosing it properly takes patience. Your vet will usually suggest an eight-week elimination diet using a hydrolysed or novel-protein food, with absolutely no treats, table scraps or sneaky licks of another pet's bowl. If the signs settle, the old food is reintroduced to confirm the trigger. Never start a home-cooked or raw diet without veterinary guidance, as it is easy to get the balance wrong.

Environmental triggers: pollen, dust and mould

Environmental allergies follow the British seasons. Tree pollen runs roughly March to May, grass pollen peaks from May to July, and weed pollens linger into early autumn. Harvest mites, active in late summer, cause maddening itching on paws and ears after walks through long grass.

House dust mite allergy, by contrast, tends to be year-round and often worsens when the heating goes on in autumn. Mould spores in damp bathrooms, conservatories and around window frames can also be a factor. Practical steps that genuinely help:

• Wipe paws and rinse the coat with a damp microfibre cloth after garden visits
• Wash cat bedding weekly at 60°C and swap fluffy bedding for washable covers
• Vacuum with a good filter and damp-dust surfaces rather than dry dusting
• Keep windows closed on high pollen days and dry laundry indoors
• Avoid over-bathing — too much shampoo strips the skin's natural oils. Use only a vet-approved product

Household irritants worth banishing

Not every reaction is a true allergy. Plenty of cats simply react badly to everyday irritants, and removing them can make a surprising difference.

• Plug-in air fresheners, scented candles and reed diffusers
• Aerosol cleaning sprays, strong bleach solutions and carpet shampoos
• Cigarette and vape smoke, which are well-known asthma triggers
• Dusty or heavily perfumed cat litter; plastic bowls can also irritate chins
• Certain houseplants — lilies in particular are dangerously toxic, not merely irritating, and should never be in a cat's home

Switch to unscented, low-fume cleaning products, choose a dust-free or paper-based litter, and use stainless steel or ceramic bowls. Keep the litter tray away from draughty, dusty corners.

When to call the vet

Some signs need urgent attention. Sudden swelling of the face, lips or eyelids, hives, difficulty breathing, or vomiting and diarrhoea within an hour of eating can indicate a severe reaction. Contact your vet straight away, using the out-of-hours service if necessary.

Book a routine appointment if your cat is losing sleep through itching, overgrooming to baldness or broken skin, suffering repeated ear infections, losing weight, or having diarrhoea that lasts more than a few days.

Your vet will first rule out other causes — fleas, mites, ringworm, bacterial infections and thyroid problems can all mimic allergies. From there, options include a proper flea plan, a structured elimination diet, allergy testing, medicated shampoos, and medications such as steroids or ciclosporin for stubborn cases. Antihistamines, so effective in people, rarely do much for cats.

Allergies are manageable rather than curable, and most cats do well with a combination of avoidance and sensible veterinary treatment. Cats hide discomfort beautifully, so trust your instincts — if something feels off, it is always worth asking.