Between 5 and 10% of the human population has at least some sensitivity to cats. Symptoms range from eye irritation, sniffling, and sneezing to life-threatening asthma attacks. Allergic reactions tend to appear in early adulthood, but you can develop the allergy at any time. Some people react almost instantly; others have a 4–8 hour delay between exposure and reaction.

Encouragingly, recent studies indicate that childhood exposure to cats may actually reduce the risk of allergic disease such as asthma. So does breast-feeding of infants.

What you're actually allergic to

There are seven known cat allergens, shed in saliva, skin secretions, and (to some extent) urine. The major one is a protein called Fel d 1, secreted primarily in saliva and skin and spread throughout the coat during grooming. Dried skin particles (dander) may carry the protein, but the allergen is not an integral part of dander or the coat itself.

Fel d 1 particles are very small, so they hang in the air and are easily inhaled. They're also sticky — they cling to draperies, upholstery, bedding, even walls and ceilings. Cat allergen has been detected in homes up to six months after the cat has been removed (and in homes that never had a cat at all).

Are some breeds “safe”?

Allergen levels don't differ meaningfully by breed. Shorthaired cats produce about the same amount as longhaired cats. One study suggested light-colored cats may be slightly less allergenic; others found no difference. There is no reliable way to identify a cat that won't set off your symptoms short of spending time with them.

Hairless breeds like the Sphynx are not hypoallergenic. They still have a fine downy coat, still groom themselves, and still spread the protein. Their only advantage is carrying fewer secondary allergens (pollen, dust) on the coat.

Strategy 1: Treat the Cat

Daily brushing or combing removes hair and dander that carry the protein. Have someone other than the allergy sufferer do it, ideally in a room they can avoid (or outside).
Manage underlying skin conditions — dry, scaly skin amplifies the problem.
Weekly bathing with a cat-safe, anti-allergen shampoo can help if your cat tolerates it. Don't over-bathe — it dries skin and can increase protein secretion.
Ultra-low-dose Acepromazine added to food daily changes the chemistry of the cat's saliva and reduces allergenic protein. Anecdotally, about 50% of people see symptoms cease completely, 25% see improvement, and 25% see no change. Ask your vet about the “Ace Allergy Drops” recipe (typically 5–6 drops daily for an adult cat). The dose is so small it has no behavioral effect.
Diet change can do wonders. Adding Omega-3 fatty acids keeps skin supple and healthy. Many people who switch their cats to homemade or raw diets report their allergies diminish or disappear. At minimum, get rid of the dry food.
Do not declaw for allergies (or any other reason). It provides no allergy benefit and is harmful to the cat.

Strategy 2: Manage the Environment

HEPA-filtered vacuum. An ordinary vacuum blows tiny allergen proteins around the room. A HEPA vacuum actually captures them. The allergy sufferer should never be the one vacuuming.
Judicious dusting can reduce airborne allergens by 95%. Spray furniture polish directly on the surface (not the cloth) to keep particles down.
Limit fabrics. Carpet accumulates 100× more cat allergen than hard floor. Blinds beat drapes. Use hypoallergenic pillows instead of feather.
Keep the cat out of the bedroom to create an allergen-free sleep zone. Transition gradually to avoid triggering behavior issues.
Freestanding HEPA air purifier in every room with fabric (at minimum, the bedroom). Choose a model rated for at least 2× the room's square footage.

Strategy 3: Guard the Guardian

Wash hands after every petting session — iron-clad habit.
Keep up with laundry. Wool and polyester retain more allergen than cotton.
If you get rashes or hives, discourage licking and love-bites — saliva is the primary source.
Consult an allergist. Rarely is someone allergic to only one thing — the cat may just be the last straw on top of existing sensitivities.
Medication works for some, not others. Diphenhydramine (Benadryl) is safe long-term but can be sedating. Talk to your physician about ongoing prophylactic use.
Immunotherapy (hyposensitization). Small, gradually increasing doses of the protein retrain the immune system not to overreact. It's slow — two months to a year to take hold, sometimes years for maximum benefit — but clinically and anecdotally effective.
Holistic remedies worth trying: a Neti pot or saline nasal spray, Omega-3 fatty acids, Quercetin and other antioxidants, Stinging Nettle (natural antihistamine), Butterbur, homeopathy, acupuncture, simplifying your diet (especially eliminating wheat and corn), and stress management.

The bottom line

It may take some trial and error to find the right combination. But people manage to live with thousands of airborne allergens every day — and aren't those big eyes and all that unconditional love worth it?

Allergic to Cats? How to Live With a Cat Anyway