What causes the allergy
Most people with cat allergy react to a protein called Fel d 1. It is made mainly in the skin and in saliva, is spread over the coat when the cat grooms itself, and sticks to tiny flakes of skin that float in the air and settle on furniture, clothes and walls. The hair itself is not the allergen, only a carrier. The particles are so small and sticky that they stay in a home for months after a cat has moved out, and they are found even in schools and offices where no cat has ever been, brought in on people's clothes.
No cat is fully hypoallergenic
Every cat produces Fel d 1, but the amount varies between individuals. Intact males usually produce the most, and neutering lowers the level. Some breeds, such as the Siberian, are often said to cause fewer reactions, but the differences between individual cats are larger than between breeds, and a hairless or curly coat does not remove the protein. Anyone with an allergy who dreams of a cat should spend time with that particular cat, or with its parents, preferably more than once, before deciding, and talk to their doctor about how strong the allergy is.
Lowering allergens at home
Keep the cat out of the bedroom so there is one room with fewer allergens. An air purifier with a HEPA filter and a vacuum cleaner with a HEPA filter help, and smooth floors and washable covers are easier to keep clean than rugs and heavy curtains. Wash bedding, throws and the cat's blankets often, wash your hands after cuddling, and let someone without allergy clean the litter box and brush the cat, preferably outdoors. A cat food with an egg-based ingredient that binds Fel d 1 in the saliva has been shown to lower the active allergen on the coat, and wiping the coat with a damp cloth helps for a while.
Treatment and honest planning
Antihistamines, nasal sprays and eye drops ease mild symptoms, and some people are helped by allergen immunotherapy, where the body gets used to the allergen over several years. Wheezing, asthma or breathlessness around cats should always be assessed by a doctor, since allergy can get worse over time. For breeders: be open with buyers who mention allergy, invite them to visit before they reserve, and agree in advance on what happens if the kitten has to be rehomed, so neither the family nor the kitten ends up in a difficult situation.