My cat scratches a lot: fleas, allergies and other causes of itching
Scratching now and then is normal. Scratching, licking or chewing at all hours, with scabs or bald patches, is not. Itching in cats has many possible causes, but it is investigated in a logical order, and the first suspect is almost always the simplest one: fleas.
How itching shows in a cat
An itchy cat does not always scratch where you can see. Many overgroom, sometimes in secret, until they pull their fur out, and what you see is areas of short or thin fur on the belly, thighs or flanks. Others scratch the head and neck until they make sores. Vets recognise several typical patterns: miliary dermatitis, with small scabs like millet seeds along the back and neck; head and neck lesions from scratching; symmetrical alopecia that the cat causes by licking; and the eosinophilic granuloma complex, with red, moist plaques on the belly or thighs, or an ulcer on the upper lip. All of them can have the same underlying cause.
Always fleas first
Fleas and flea allergy dermatitis are the most common cause of itching in cats. In an allergic cat, an occasional flea is enough to make them scratch non-stop, and because they groom so much, they swallow it and you never see it. So not seeing fleas rules nothing out. Look for the black specks of flea droppings with a fine comb over damp white paper and, above all, use an effective cat flea treatment on every animal in the home for at least two or three months before moving on to other tests. Many "allergic" cats are cured by this alone. And never use dog products containing permethrin: they are toxic to cats.
Mites and fungi
Ear mites (Otodectes) cause intense itching of the ears and head, with dark, dry wax like coffee grounds; they are common in kittens and highly contagious between animals. Other skin mites, such as Cheyletiella, which causes scaling like moving dandruff, or mange mites, are less common. Ringworm, or dermatophytosis, is a fungal infection that causes round bald patches with scaling, sometimes with little itching, and it spreads to people, especially children, and to other animals; it is typical of kittens, Persians and shelter cats. The vet diagnoses it with a Wood's lamp, examining hairs under the microscope, culture or PCR.
Food allergy
Some cats are allergic to a protein in their food, almost always one they have been eating for a long time, such as chicken, beef, fish or dairy. It causes itching mainly on the head and neck, all year round, sometimes with vomiting or soft stools. It is not diagnosed with blood tests, which are not reliable for food allergy, but with an elimination diet: for at least eight weeks, the cat eats only a veterinary hydrolysed diet, in which the proteins are broken down so the immune system does not recognise them, or one with a protein they have never eaten. Nothing else: no treats, no scraps, no flavoured malt paste. If the itching improves and comes back when the previous food is reintroduced, the diagnosis is made.
Environmental allergy or feline atopy
Once parasites, infections and food allergy have been ruled out, the most likely cause is an allergy to environmental allergens, such as house dust mites, pollens or moulds, which in cats is called feline atopic skin syndrome. It can be seasonal or year-round, can produce any of the lesion patterns and is sometimes linked to asthma. Allergy tests are used to choose the allergens for immunotherapy, a kind of personalised vaccine, not to make the diagnosis. Treatment combines control of the itch with veterinary medication, omega-3 fatty acids, a healthy skin barrier and, in some cats, immunotherapy. It cannot be cured, but it can be well controlled.
When the cause is stress or pain
Some cats overgroom because of stress, boredom or anxiety, which is called psychogenic alopecia. But it is a diagnosis of exclusion: most cats that lick themselves bald are itchy for a medical reason, and only after ruling that out can you talk about stress. Pain also causes localised licking: a cat with cystitis may lick their belly bald, and one with arthritis may lick over a joint. Watch where they lick and whether it coincides with a change at home or any other symptom.
How the vet investigates it
In a logical order, from the most common and simple to the least: a full examination of skin, coat and ears; combing for fleas; skin scrapes and cytology to look for mites, bacteria and yeasts; a trichogram, which means looking at hairs under the microscope to see if they are broken from licking or shed; fungal tests. Then rigorous flea treatment and treatment of any secondary infections. If it persists, an elimination diet. And if it still persists, a diagnosis of atopy. It is a process that takes weeks and patience, but skipping steps is the main reason itching drags on forever.
What not to put on them
No human creams or ointments without asking: many cats lick them off and some contain substances toxic to them, and corticosteroid creams can make a fungal infection worse. Essential oils such as tea tree are toxic to cats even in small amounts. Do not use dog or human shampoos. Do not give antihistamines or other medicines from home without veterinary advice. And, once again, no dog spot-ons: permethrin is one of the most common poisonings in cats. If they are injuring themselves while you wait for the appointment, a cone or a body suit protects them.
What it can cost
As a guide in Spain in 2026: a general dermatology consultation, 40 to 70 €; with a veterinary dermatologist, 70 to 130 €; cytology and scrapes, 20 to 60 €; fungal culture or PCR, 30 to 80 €; flea treatment for all the animals for three months, 40 to 150 € depending on how many there are; hydrolysed diet for the elimination trial, 40 to 80 € a month; allergy tests, 150 to 300 €; immunotherapy, 200 to 400 € a year. An atopic cat may need ongoing treatment, with a variable monthly cost depending on the medication.
Itching in cats is investigated in order: fleas first, even if you cannot see them, with rigorous treatment of every animal; then mites, fungi and infections; then an elimination diet of at least eight weeks; and finally environmental allergy. No creams, essential oils or dog spot-ons.
Educational content from Michipedia, translated from the Spanish original. It does not replace the advice of a vet or a feline behaviour specialist. Every cat is an individual.