Allergies are an overreaction of your immune system to certain substances that are considered harmless. When you come into contact with an allergen, your body begins to fight off unwanted invaders. Your immune system produces immunoglobulin E, which then instructs your basophils and mast cells to send out an army of chemicals to ward off allergens. When it comes to cat allergies, the substance your body reacts to is usually a specific protein that cats secrete in their sebaceous glands and saliva. Another common source of cat allergies is dander, or skin flakes, that your cat excretes and then you touch or inhale. It’s rare for dander to cause an allergy, although often the dander and protein are carried on the coat when the skin peels or the cat grooms itself.
Although many people think that furry cats are allergy free, they are wrong. Since allergens that cats produce are usually related to their skin and saliva, dander is not a big factor in the cat allergy equation. In fact, the Siberian cat, which is one of the cat breeds thought to cause the least allergic reactions, has a very thick coat. It may even be their thick fur that reduces the allergen, as it creates a barrier between the allergen-secreting skin and you. Factors that might influence how a cat is allergic include coat color — dark-colored cats seem to cause more allergic reactions than light-colored ones — and whether a cat is neutered or not — neutered cats tend to cause fewer reactions than non-neutered ones.
If you are allergic to cats, chances are you are allergic to all cats. While you may have luck with some breeds, you can generally assume that any cat will cause a reaction. However, the time it takes you to react may vary depending on your sensitivity level, how many allergens are present, and the possible breed of cat.