Causes of Cat Allergy Symptoms

"Cat allergy symptoms includes skin conditions, hair loss, respiratory problems such as sneezing and gastrointestinal or stomach problems. Skin issues are most common with symptoms such as excessive grooming, skin inflammation, hair loss, feline acne, eosinophilic plaques (large red skin lesions) and granulomas. Respiratory problems include asthma, sneezing, nasal discharge, and watery eyes. The most common cause of skin allergies are fleas, followed by contact dermatitis, atopy (inhaled or seasonal allergy such as pollen) and food allergy. A veterinarian will base an initial diagnosis on the location and pattern of skin or hair loss, and symptoms such as gastritis, diarrhea or vomiting."

Cat allergy symptoms usually effect the skin. It is less common for allergies to cause stomach problems such as vomiting and diarrhea. Common causes include reaction to fleas (flea bite hypersensitivity), scabies due to mites, and emotional problems (psychogenic alopecia).

To identify the cause of the cat allergy symptoms affecting your cat:

  1. Start by reviewing the descriptions and pictures of the feline allergy symptoms listed below.
  2. Then review the various causes and the related symptoms.
  3. If you still don't know the cause, fill out this form and our Vet will comment for free. Please include pictures of any skin condition. If you would like an immediate answer, we suggest using this online veterinary service which has Vets on call 24 hours a day.

Quick Guide to Cat Allergy Symptoms and Possible Causes

Cat Allergy Symptoms

Cat Allergy Related Cases

Other Possible Causes of Cat Symptoms

Watery diarrhea, with or without vomiting, no weight gain, slow weight gain

Food Allergy

IBD or Inflammatory Bowel Disease), Parasites, Infection

Itch and scratching on head and ears, rubbing face on furniture, irritated cat skin from rubbing

Food Allergy

mange, ear mites

Blood from rectum

Food Allergy

parasites, foreign object, infection or tumor

Straining when moving bowels

Colitis due to food allergy

Parasites, eating household or outdoor plants, Tumor


Allergy to food not normally eaten

Eating houseplants, dietary change, ingested human medication, swallowed foreign object such as a piece of thread, outdoor cats can ingest food that is tainted with salmonella,

Respiratory problems such as cat reverse sneezing or cat unable to catch breath, repeated snorting, rapid breathing through nose

Pharynx irritation due to allergy (try feeding cat soft foods to see if better

Sore throat (may require veterinary care including antibiotics and anti-inflammtories

Small scabs along back and head, hair loss along back, itch

Flea allergy dermatitis or food allergy

Condition called miliary dermatitis

Progressive cat hair loss on legs and groin, Licking hair out



cat allergy symptoms dermatitis
Cat Allergy Symptoms (feline facial allergy dermatitis)
Source: Washington State University, Dr Barbara Stein

Cat Skin Allergy Symptoms:

There are 4 general patterns that define the type of skin allergy your cat might be suffering from. These include:

For pictures and help with these cat allergy symptoms see our guide to feline skin allergies.

Natural Remedies for Cat Skin Allergy Symptoms:

It is important to see a veterinarian to help identify the underlying cause for your cat skin allergy problem. Natural remedies might also be of help. Certain herbs such as Althaea officinalis root (marshmallow) is an excellent and well-known remedy for soothing the skin – while Melaleuca alternifolia can be used externally for promoting skin health and keeping the skin clean. Remedies such as Ledum and Apis have good soothing properties and are particularly useful in soothing inflamed and irritated skin, or minor stings and wounds. One product to research if this approach is of interest is Wound Dr. which can help with ulcerated skin conditions.

Cat Food Allergy and Food Intolerance Symptoms:

Food allergy occurs when the body's immune system reacts to a specific food component (there are 40 ingredients in the typical commercial cat diet). There is a difference between and food intolerance and a food allergy. Food intolerance happens when the body is sensitive to a particular food. Allergic reactions tend to be less severe than intolerance.

cat food allergy symptoms
Cat Food Allergy Symptoms on Feline Ear
Source: Washington State University

Symptoms associated with food allergy and food intolerance include:

Even though your cat is eating the food and you would expect a reaction that is related to digestion, for some reason that researchers don't understand, the skin has a reaction. Gastrointestinal issues are only seen in 33% of cats suffering from allergy and food intolerance.

Food allergies tend to be the same across cats of different breeds, male or female. Reactions tend to occur more often in younger cats, but can be seen at any age.

Common cat allergy symptoms include itch on the face and neck (pruritic facial and neck dermatitis) or ears. In this type of allergic reaction you will notice crusty skin, eroded skin, and ulceration (patches of skin that look different than the rest of the skin and look like it has been worn away).

Other symptoms include hair loss (traumatic alopecia), usually due to your cat over grooming, miliary dermatitis (skin with collections of pronounced red bumps), eosinophilic plaques (well-defined, raised, ulcerated and extremely pruritic lesions that occur on the skin of cats, usually on the abdomen or hind legs) and scaling and shedding of the skin and usually accompanied by redness (exfoliative dermatitis).

Flea Bite Allergy Symptoms (flea-bite dermatitis)

Symptoms of an allergic reaction to cat flea bites include itch and raw skin from scratching. Skin conditions are called eosinophilic plaques (well-defined, raised, ulcerated and extremely pruritic lesions that occur on the skin of cats, usually on the abdomen or hind legs).

cat flea allergy symptoms
Cat Flea Allergy Symptoms called Eosinophilic plaques which form as a result of itching or scratching from cat flea allergy
Source: Washington State University, Dr Barbara Stein

Symptoms are usually seen during warm weather at the peak heat of the summer. If fleas are in the house you could see symptoms year round.

Swollen Head Allergy (urticaria)

This condition is caused by an allergic reaction to food. You will see swelling around the eyes and face, which may even cause the eyes to be swollen shut. Other causes are due to a reaction to an insect. A reaction can happen fast.

Your cat may be helped by a cold compress or a medication such as antihistamine. An over the counter product may be recommended such as benadryl. The dosage is 1 to 3 milligrams per pound of your cat, however, you should only do this if you check with your veterinarian first to ensure that the product is safe for your cat and the dosage is correct.

Hay Fever

Like humans, cats can suffer from environmental allergies such as hay fever. Common cat allergy symptoms aren't that different from humans with a runny nose, red eyes and sneezing.

You can help your cat by providing a bath made with colloidal oatmeal. Your cat may also be helped with an antihistamine such as benedryl as described above.

Heavy Breathing/Sinus Problems

If your cat is breathing heavily and your veterinarian cannot determine a physical cause, you can also try a natural remedy designed to help support the sinuses. One product to research is Sinu-Rite which is a proven herbal cat sinus condition solution.

References for Cat Allergy Symptoms

Feline Allergic Skin Disease – What’s New in Diagnosis and Management?
Peter Hill
Senior Lecturer in Veterinary Dermatology
Division of Companion Animal Studies,
Department of Clinical Veterinary Science,
University of Bristol,
Langford, Bristol, UK

Adverse Food Reaction in Cats
Dr. T. Willemse
Utrecht University,
Faculty of Veterinary Medicine,
Department of Clinical Sciences of Companion Animals,
Utrecht, the Netherlands


Have a Cat Health Question or Want to Share a Story that could help others?

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