Cat Allergies

Cat allergy happens when your immune system treats harmless proteins from a cat as a threat. The main one is called Fel d 1, and it comes from cat saliva, skin flakes and urine rather than from the fur itself. It sticks to tiny particles that float in the air and cling to clothing and furniture, which is why a blocked nose, itchy eyes or a tight chest can start in places where there is no cat in sight.

What cat allergy is, and what it is not

The most common misunderstanding is that cat allergy is an allergy to fur, and that a short-haired or so-called hypoallergenic breed will therefore be fine. No breed is free of Fel d 1, because the protein comes from saliva and skin, not hair. Amounts do vary between individual cats, and some people genuinely notice more symptoms with one cat than another, but breed alone does not reliably predict how you will react.

It is also not only a problem inside homes with cats. Cat allergen is light and sticky, so it settles into carpets, mattresses, upholstery and even walls, and it can stay measurable for many months after a cat has gone. It travels into schools, offices and buses on clothing. That is why symptoms sometimes make no sense until testing and a careful history put the pieces together, and why a positive test on its own does not confirm that cats are the cause of your symptoms.

Signs and symptoms

• Sneezing, a runny nose or a blocked nose
• Itchy, red or watery eyes
• Itching in the nose, roof of the mouth or throat
• Coughing, wheezing or chest tightness, especially in people who also have asthma
• Skin redness, hives or itching where a cat has licked or scratched
• Worsening eczema in some people
• Tiredness and poor sleep from a blocked nose at night

Reactions range from a mildly stuffy nose to chest symptoms that need urgent treatment, and the same person can react differently depending on how much allergen is around and for how long.

What raises the risk

Some things cannot be changed:

• A personal or family history of allergy, asthma or eczema
• Already being allergic to other airborne triggers such as dust mite or pollen
• Living with asthma, which makes cat exposure more likely to affect the chest

Others can often be worked on, usually with support from a health care team:

• Regular close contact with cats at home, at work or when visiting others
• Carpets, upholstered furniture and bedding that hold cat allergen for months
• Tobacco smoke in the home, which irritates the nose and airways alongside allergens
• Poor indoor ventilation and a lack of high-efficiency filtration

How cat allergy is diagnosed in Canada

Cat allergy is confirmed by an allergist using a skin prick test, in which a drop of cat allergen extract is placed on the forearm or back, the skin is lightly pricked, and the reaction is measured a short while later. A blood test for allergen-specific IgE to cat is used instead when skin testing is not suitable, for example if you take antihistamines you cannot stop or you have widespread skin disease. Component testing for the specific protein Fel d 1 is available in some centres. Results are always read alongside your symptom history, because sensitisation on a test and symptoms in real life are not the same thing.

Treatment and day-to-day management

Clinical research for Cat Allergies is enrolling. See the current studies ↓

Care for cat allergy usually combines reducing how much allergen you breathe in with medicines that settle the reaction, and it takes account of whether your chest is involved. Depending on your symptoms, your test results and your household, a health care team may discuss:

• Allergen reduction measures, such as high-efficiency air filtration, removing carpets, and keeping cats out of the bedroom
• Oral antihistamines and intranasal antihistamine sprays, available over the counter or by prescription
• Intranasal corticosteroid sprays and allergy eye drops
• Allergen immunotherapy given as injections under the skin or, where available, under the tongue, through allergists
• Asthma care where cat exposure sets off chest symptoms, including inhaled controller therapy and a written asthma action plan

Rehoming a cat is a decision no page can make for anyone, and it is not the only option on the table. These are decisions for you and your own clinician, and this page is not a recommendation about any of them.

When to talk to a doctor

• Call 911 if exposure causes difficulty breathing, wheezing that does not settle with your reliever inhaler, swelling of the lips, tongue or throat, or faintness, since these can be signs of a severe reaction.
• Seek medical care the same day if a cat scratch or bite becomes red, swollen, warm or painful, or if you develop a fever afterwards.
• Book an appointment with your family doctor, or ask about an allergist referral, if symptoms last most days, disturb your sleep, or are no longer controlled by over-the-counter treatments.

Why clinical research matters for cat allergy

Avoiding cats is not realistic for many households, and current allergy shots take three to five years and are not an option for everyone, so researchers are looking for shorter and more targeted approaches. It is also still unclear why some people sensitised to cat allergen develop severe asthma symptoms while others have only nasal symptoms. Work now underway includes modified and peptide-based immunotherapy aimed at Fel d 1, monoclonal antibodies targeting IgE and other allergic pathways, intralymphatic immunotherapy, and cat-directed approaches such as antibody-containing cat food and vaccination of the cat itself.

Canada also has no national figure for how many people are allergic to cats, which limits how well services can be planned. Studies are how the gaps get filled. Taking part is voluntary, you give informed consent before anything begins, and you can withdraw at any time without affecting the care you get from your own doctor. No one can say in advance whether a study will help you personally.

Learn more from Canadian sources

• Canadian Society of Allergy and Clinical Immunology
• Asthma Canada
• Canadian Lung Association: Lung Health Information Line
• Public Health Agency of Canada: climate change, air contaminants and your health